key: cord-0893451-dl4ssv5f
authors: Karussis, Dimitrios
title: Multiple Sclerosis
date: 2016-10-24
journal: International Encyclopedia of Public Health
DOI: 10.1016/b978-0-12-803678-5.00295-2
sha: f84676e126738b90decbeb0dec965de14dc0d326
doc_id: 893451
cord_uid: dl4ssv5f

Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) characterized by loss of motor and sensory function that results from immune-mediated inflammation, demyelination, and subsequent axonal damage. Clinically, most MS patients experience recurrent episodes (relapses) of neurological impairment, but in most cases (60–80%) the course of the disease eventually becomes chronic and progressive, leading to cumulative motor, sensory, and visual disability, and cognitive deficits. The course of the disease is largely unpredictable and its clinical presentation is variable, but its predilection for certain parts of the CNS, which includes the optic nerves, the brain stem, cerebellum, and cervical spinal cord, provides a characteristic constellation of signs and symptoms. Several variants of MS have been nowadays defined with variable immunopathogenesis, course and prognosis. Many new treatments targeting the immune system have shown efficacy in preventing the relapses of MS and have been introduced to its management during the last decade.

Ó 2017 Elsevier Inc. All rights reserved. This article is an updated version of the previous edition article by Charles M. Poser, volume 4, pp. 469-4814, Ó 2008, Elsevier Inc. 

The overall prevalence of the disease varies in different regions of the globe, ranging from 15/100 000 to 250/100 000 (Kingwell et al., 2013; Rosati, 2001) . According to WHO, it is estimated that more than 2 million people worldwide suffer from multiple sclerosis (MS) and the disease is one of the most common causes of neurological disability in young adults. Some have suggested that this variability follows a certain pattern greatly depended on the latitude of each country ( Figure 1) . However, epidemiological data depict that the disease varies greatly between areas of similar latitude (Ebers and Sadovnick, 1993) . Nevertheless, MS prevalence is higher in Northern than in Southern Europe, as it is in the Americas ( Table 1) . This is most likely due to differences in the ethnicity of the populations: MS is much more frequent in people of Scandinavian (either direct or indirect) descent including Americans in the northern states. On the other hand, the prevalence is high in 'southern' countries, such as Croatia, Israel, Kuwait, and South Africa. There is a great difference in MS prevalence between geographically close areas, such as Malta and Sicilia or Sardinia. The disease is extremely rare in Hindus living in Mumbai, but not uncommon in Parsis living in the same city. Almost no cases of MS have been reported in North or South American Indians, in Samis (Lapps), Eskimos, Australian Aborigines, Maoris, Melanesians, Micronesians, or Polynesians. MS is also extremely rare in black Africans. Israel is a good paradigm to evaluate the variable incidence of MS in subpopulations at the same geographical region and under similar environmental conditions, since there are distinct and well-distinguished ethnic groups living in the country and new immigrants arriving from countries in which the prevalence of MS is variable. The prevalence of MS is three times higher in the Jewish than in the Arab population. The disease is also three times more frequent in Askenazy Jews as compared to those of Sefaradic origin (Alter et al., 2006) .

Arab populations in the region have MS at low to medium rates and the prevalence rates in Christian Arabs are thrice as high as for Muslim Arabs, suggesting that different risk factors operate in these two subethnic groups (Alter et al., 2006; Milo and Kahana, 2010; Siegel et al., 2012; Karni et al., 2003) . Etiopathogenesis MS has been described as a disease of unknown etiology, implying the involvement of several factors and not a single cause. These include a genetic background, infectious agents, and hormonal and environmental factors. All these, in a complex interplay, give rise to an immune-mediated attack of the myelin sheath. 

The striking differences in prevalence in similar environments strongly suggest an important role of genetic factors. There is a familial occurrence rate of about 10-15%. The age-adjusted risk is higher in siblings (3%), children (1-2% risk in each child when one parent suffers from MS and 7% when both of them suffer from MS), than in second-and third-degree relatives.

There is only a 25-35% concordance in monozygotic twins. Adopted offspring or other nonbiological relatives have no increased risk (Sadovnick, 1994) . Because of these indications, numerous studies of genetic markers have been carried out (International Multiple Sclerosis Genetics Consortium et al., 2011) , but to date only few secure candidates or regions have been identified and the associations are rather weak (Dyment et al., 1997; Ebers, 1996; Sawcer et al., 1997) .

The strongest genetic association in MS patients has been with the class II major histocompatibility complex (MHC), and specifically the alleles of the human leukocyte antigen (HLA) system DR15 and DQ6 (DRB1*1501 and DBQ2*0602) and the gene for tissue necrosis factor encoded within the same linkage group. A specifically different association (with DR4 and its DRB1*O405-DQA1*0301-DQB1*0302 genotype) is seen in Mediterranean populations, primarily Sardinians. The haplotype DRB1*1501, DQA1*0102, DQB1*0602 was found to be associated with MS among both Ashkenazi and non-Ashkenazi patient Kwon et al., 1999) .

In general it seems that the existing data support the theory that MS is a polygenic disease, similarly to other autoimmune diseases, and that immune system-related genes (especially at the HLA region) largely contribute to the risk to develop the disease.

A number of infectious agents have been reported as potential etiological agents (Ascherio and Munger, 2007; Gilden, 2005; Steelman, 2015) . They include the varicella zoster (Sotelo et al., 2007 (Sotelo et al., , 2008 , corona viruses, measles, Epstein-Barr, herpes simplex type 6, and canine distemper viruses; the human T-cell lymphotropic virus (HTLV)-l, an 'MS-associated agent'; and, most recently, Chlamydia. None of these has been confirmed, but the idea is mainly based on the mechanism of molecular mimicry, that is, the molecular similarities between antigens on the surface of bacteria or viruses and self-myelin proteins, leading therefore to a false response against myelin, in genetically susceptible individuals. The seasonal variations in MS exacerbations and the somehow increased incidence following vaccinations may also support the infectious theory (Sibley and Foley, 1965; Goodkin and Hertsgaard, 1989; Andersen et al., 1993; Kriesel et al., 2004; Kriesel and Sibley, 2005; Kneider et al., 2009; De Keyser et al., 1998; Sibley et al., 1985; Correale et al., 2006; Banwell et al., 2007; Edwards et al., 1998; Pohl et al., 2006; Alotaibi et al., 2004; Buljevac et al., 2005 Buljevac et al., , 2003 Horakova et al., 2013; Kvistad et al., 2014; Lindsey et al., 2009; Ordonez et al., 2004; Burgoon et al., 2009; Leibovitch and Jacobson, 2014; Mulvey et al., 2011; Karussis and Petrou, 2014; Simpson et al., 2014) . In the latter case (of vaccinations) the pathogenetic mechanism may involve bystander activation of the immune system, due to adjuvants that are used in the preparation of vaccines.

The putative time of acquisition of MS has been generally accepted as being at puberty in most if not all patients. This was deduced from the study of MS in English immigrants to South Africa, noting that the disease rarely developed in those who had immigrated before the age of 15, compared to the number that would have developed it in England (Dean and Kurtzke, 1971) . Similar studies confirmed this observation. In support of this concept is that the secretion of female sex hormones, which play an important role in enhancing immune responses, significantly increases at puberty (Poser, 2006) . In addition to the fact that first MS signs appear often during puberty or shortly after it, data indicating changes in the activity of MS during the phases of menstrual cycle (Pozzilli et al., 1999) further support a role of the hormonal milieu as an additional risk factor for the disease. The rate of relapses of MS declines during pregnancy, especially in the third trimester, and increases during the first 3 months postpartum before returning to the prepregnancy rate (Korn-Lubetzki et al., 1984; Confavreux et al., 1998; Coyle, 2014; Runmarker and Andersen, 1995) .

In support to the previous, treatment with high-dose gynecological hormones (such as in IVF) was shown to be associated with a higher risk for MS onset or for a relapse of the disease (Michel et al., 2012) . Other investigators, however, failed to find significant correlation between pregnancy and MS activity .

Since genetics alone cannot explain the variability in MS prevalence, it is likely that some environmental factors also influence the acquisition of the disease. Many studies of an enormous variety of possible agents and factors that could influence the acquisition or development of the disease have been carried out in various countries, with controversial results. Usually these factors are related to the clinical onset rather than the acquisition of MS (Ebers, 2008; Ascherio, 2013) .

The influence of environmental factors is most apparent in considering the effects of migration on prevalence and incidence rates. Frenchmen living in Africa have a considerably lower prevalence rate than those living in France. The children of West Indian and Asian immigrants to the United Kingdom have the same incidence and prevalence rates as native-born Englishmen, and the Israel-born children of both Ashkenazi and Sephardic Jews also have the same prevalence rates, although their parents' rates are quite different. On the other hand, Jewish immigrants coming from Northern European countries carry a much higher risk for MS but only when they arrive in Israel after the age of 5-13 years, depending on both the length of 'exposure' and the stage/level of maturation of the immune system (Milo and Kahana, 2010; Kahana et al., 1994; Alter et al., 1978) .

Most Martinican Blacks who developed MS had spent significant periods of time in metropolitan France before acquiring the disease. The situation in Hawaii illustrates what appears to be a unique, contradictory situation in which the presumably same environment exerts opposite effects on different ethnic groups (Alter et al., 1971) . For persons of Japanese extraction living in Hawaii or in California there is an increased risk of MS compared with those living in Japan (6.5 vs 2.1); for Caucasians raised in Hawaii it appears to offer some protection against MS (10.5 vs 34.4). It is difficult to conceive of environmental factors having such a disparate effect unless the genetic makeup of the individual also plays a role in the equation. The existence of a premorbid genetic marker such as the MS 'trait' could provide an explanation.

Epidemiological studies have demonstrated the primary importance of genetic factors modified by an as yet unrecognized environmental one.

Among the environmental factors that may possibly include toxic substances' exposure, air pollution, irradiation, stress, and sunlight exposure (and they may be responsible for the growing incidence of MS and autoimmunity in general in the 'Western' world), vitamin D, seems to play an important role (James et al., 2013; Smolders et al., 2009; Salzer et al., 2012 Salzer et al., , 2014 .

Variation in MS incidence among individuals born at certain seasons of the year may also indicate that sunlight exposure (and possibly vitamin D levels) of the mother may increase or decrease the risk for MS in the newborns. Children born in April or May were found to be of higher risk to develop MS Willer et al., 2005; Dobson et al., 2013) . Summarizing the pathogenetic model on the basis of the above-described available data, it seems that MS is the result in a genetically susceptible subjectof the activation of the immune system by different infectious agents, which initiates a pathogenetic cascade that is not fully understood and which eventually leads to the destruction of the myelin and the axons.

The rather low rate of concordance of MS in monozygotic twins has never been fully explained, but it supports the possibility of multiple factors (and not only genetics) involved in disease pathogenesis; genetically susceptible individuals may develop MS only if and when an external trigger (infectious? environmental?) will trigger the onset. Poser (2006) has suggested a status that he defined as MS 'trait' which is different from asymptomatic MS and may never develop into the disease. It results from the action of an antigenic challenge to the immune system of a genetically vulnerable person that does not cause damage to the nervous parenchyma. A subsequent environmental viral-antigenic event in some MS 'trait' 'carriers' can change the trait into the disease. This event could be an infection, which need not be symptomatic, or a vaccination. The MS may become symptomatic, remain asymptomatic, or be manifested only by lesions visible by MRI (RIS). It is likely that the development of the MS 'trait,' defined as 'activation,' occurs early in life, whereas the transition from MS trait to MS (i.e.,'acquisition') takes place at puberty in most patients, when the immune system is made more vulnerable by the outpouring of female sex hormones.

The pattern of destruction of myelin is unique to MS as compared to the other demyelinating (e.g., acute disseminated encephalomyelitis, ADEM) or dysmyelinating (e.g., metachromatic or adrenoleukodystrophy), diseases: it consists of plaques that are sharply demarcated from the normal white matter surrounding them ( Figure 2) . They have been aptly described as 'cut out with a cookie cutter.' In contrast, the inflammatory lesions in ADEM are almost invariably perivascular and often become confluent. Unless the pathognomonic sharp edge of the MS lesion is captured by the biopsy, it is sometimes impossible to clearly differentiate it from ADEM.

Plaques are most commonly seen in the optic nerves and chiasm, the periventricular centrum semiovale, the brain stem, the cerebellar hemispheres, and the cervical spinal cord. Although most plaques are seen in the white matter, they may involve the subcortical U-fibers and extend into the gray matter. The cortex, thalamus, the basal ganglia, and the dentate nuclei may all be affected. Lesions of the sensory nucleus of the trigeminal nerve, the intraparenchymal portion of the facial, and some of the connections of the acoustic nerve are frequently involved, but peripheral nerves are spared. Asymmetry of the lesions is the rule.

Inflammatory cellular infiltrates and edema are almost invariably seen in the walls of small blood vessels and the surrounding parenchyma at the edges of the plaques. Similar changes in the walls of capillaries and venules can also be seen in the so-called 'normally appearing white matter' (NAWM) in MS CNS. One of the earliest changes is separation of the myelin lamellae by vesicular edema, fragmentation of the sheath, invasion by macrophages that engulf the myelin debris, and eventual denudation of the axon. Most of the plaques show periaxile demyelination, the axon appearing intact, but older lesions clearly show axonal and neuronal degeneration. Clumps of large abnormal gemistocytic astrocytes may be seen near the lesions; these are occasionally mistaken for astrocytomas.

The MS variants, Marburg's acute MS, Balo's concentric sclerosis, and Schilder's 1912 type diffuse sclerosis, exhibit similar but also distinct pathological features (Poser and Brinar, 2004a,b) .

Perivenular inflammatory lesions involving infiltrating mononuclear cells are evident in the earlier phases of the disease Frohman et al., 2006; Steinman, 2001) . This inflammation leads to damage or loss of oligodendrocytes and demyelination with resulting disruption of the conduction of neuronal signals in the affected regions. In the initial stages of MS, compensatory pathways (such as the upregulation of ion-channels in the affected areas) may partially restore conduction and reverse the neurological dysfunction. As the disease progresses, significant axonal loss and eventually neuronal damage occurs (Trapp et al., 1998) and the lost function becomes permanent and nonreversible (Steinman, 2001; Trapp et al., 1998; Grigoriadis et al., 2004) .

It is widely accepted that the inflammatory process in MS is caused or propagated by an autoimmune cascade (Figure 3a) , involving mainly T cells that target myelin selfantigens (Zhang et al., 1994; Allegretta et al., 1990) , possibly through mechanisms known as molecular mimicry (crossreactive antigens expressed by viruses or other microorganisms and myelin components) (Wucherpfennig and Strominger, 1995) . The 'autoimmune hypothesis' is also supported by the finding of increased incidence of other autoimmune diseases in patients with MS and their first-degree relatives (Barcellos et al., 2006; Ramagopalan et al., 2007) .

An alternative hypothesis is that myelin-specific T cells that are present 'naturally' may expand to critical pathogenic quantities (Venken et al., 2010) due to malfunctioning immunoregulatory mechanisms (such as those involving the Th2, Th3, and CD8 T cells and the regulatory T cells: Tr1 and Treg).

Although the autoimmune hypothesis is attractive and supported by concrete data (including the efficacy of immunomodulatory treatments in MS), the initial insult which initiates the whole immune-mediated cascade is still obscure. Environmental, genetic, and infectious factors seem to play an important role in MS pathogenesis, but it seems that the role of any putative infectious agent is to trigger/drive the autoimmune process (Venken et al., 2010) , rather than to serve as the primary target of infiltrating cells. In any case, T cells of the Th1 and Th17 phenotype specific for myelin antigenic epitopes seem to represent the common final pathogenetic effector pathway, regardless of the initial insult of the disease (Tesmer et al., 2008; Korn et al., 2009; Kebir et al., 2007) . Following the initial damage of myelin, the blood-brain barrier opens and myelin-related antigens are released in the peripheral blood causing further activation of the anti- myelin autoreactivity and production of new anti-myelin lymphocytes with a profile of T-cell receptor recognition that probably changes during the course of the disease (epitope spreading) Miller, 1996, 2002; Quintana et al., 2014) . However, MS is not a homogenous disease and it is now increasingly recognized that it has several distinct immunopathological profiles, including prominent humoral immune mechanisms in some MS patients (Lucchinetti et al., 2000) .

The initial stages of the autoimmune cascade in MS are probably initiated in the peripheral immune system. Following activation by the macrophages and dendritic cells (antigenpresenting cells: APC), Th1 and Th17 lymphocytes, which express the antigens specific for myelin, T-cell receptors (TCR), proliferate and begin to express on their membranes, adhesion molecules, and chemokine receptors that enhance their ability to extravasate to the site of inflammation in the CNS (Sharief et al., 1993a,b; Tsukada et al., 1993a,b,c; Washington et al., 1994) (and to produce interleukin (IL)-2, IL-17, tumor necrosis factor-alpha (TNFa) and interferon-gamma (IFNg) (pro-inflammatory cytokines)). This migration possibly follows 'damage signals' from the CNS tissue or is due to an opening/destruction of the blood-brain barrier. Adhesion molecules such as VLA4 are crucially important for this process and their blockage may prevent the extravasation of the lymphocytes through the blood vessels' endothelium (Yednock et al., 1992; Polman et al., 2006) . Interestingly, the best existing evidence that MS is indeed an autoimmune disease and that the whole process is initiated in the periphery comes from the reported evidence of high efficacy in MS (and the 'rebound' of MS activity following their discontinuation) of medications that specifically block the migration of the lymphocytes into the CNS (such as natalizumab which targets the CD40L molecule) .

The innate immunity has also shown to play an important role in MS pathogenesis and the inflammatory immune cascade (Gandhi et al., 2010) and especially the dendritic cells, as well as the NK cells, mast cells, gdT cells, and microglial cells (Mayo et al., 2012) . Specifically the role of NK cells has been controversial.

The involvement of NK cells in the pathophysiology of autoimmune diseases has been studied for many years (Matsumoto et al., 1998; Zhang et al., 1997) , but their actual role of NK cells in CNS autoimmunity is still not clear (Morandi et al., 2008) . In vitro NK cells show cytotoxic activity toward oligodendrocytes and other glial cells, such as astrocytes and microglial cells during inflammation.

NK cells may also play a role in CNS protection and repair, as these cells have the ability to produce neurotrophic factors (Hammarberg et al., 2000) . Several studies described a beneficial role of NK cells in mouse or rat EAE (Matsumoto et al., 1998; Zhang et al., 1997; Galazka et al., 2007; Huang et al., 2006; Xu et al., 2005) .

In humans, a decreased cytotoxic activity of circulating NK cells has been described during clinical relapses of MS (Kastrukoff et al., 1998 (Kastrukoff et al., , 2003 , whereas an increase of the 'NK2' NK cell subpopulation was observed during the remission phase (Takahashi et al., 2001) .

Upregulation of the CD56 bright NK cell subset by immunomodulatory therapies, such as daclizumab (Bielekova et 2006), IFNb (Saraste et al., 2007) , and cyclophosphamide may contribute to the beneficial clinical effects of these medications (Bielekova et al., 2006) . B cells have traditionally been considered to play a secondary, producing antibodies that may promote tissue destruction by recruiting macrophages and through activation of the complement pathway (Hawker, 2008) . Additionally, activated B cells can act as antigen-specific APCs for T cells and produce costimulatory molecules that influence the differentiation of T cells into Th1 or Th2 cells (Zouali, 2008) . Patients with MS have increased B-cell numbers in the CNS, mainly memory cells and short-lived plasmablasts (Cepok et al., 2005) . Plasmablasts persist in the cerebrospinal fluid (CSF) throughout the course of MS, and the numbers of these cells correlate with intrathecal immunoglobulin G (IgG) synthesis (oligoclonal antibodies, one of the hallmarks of MS diagnosis) and with active inflammatory disease (Cepok et al., 2005; Owens et al., 2006) . Moreover, B cells, plasma cells, autoantibodies, and complement have been detected in MS lesions (Prineas and Graham, 1981; Archelos et al., 2000) , indicating their implication in demyelination. Additional indications for antibody-mediated mechanisms in MS come from the presence of ectopic lymphoid follicles in the CNS of patients with MS (Cepok et al., 2005; Serafini et al., 2004; Krumbholz et al., 2006; Magliozzi et al., 2007) , especially those with progressive disease. It appears, therefore, that as the disease evolves into the progressive stage, the inflammation becomes compartmentalized and predominantly mediated by B cells. Additional findings that may explain progression of MS and its correlation with 'slow' in situ inflammation come from reports showing significant meningeal, cortical, and deep gray matter inflammatory lesions predominant in progressive MS or in patients with advanced disability and represent a bad prognostic factor (Serafini et al., 2004; Magliozzi et al., 2007; Ruggieri et al., 2015; Haider et al., 2014; Cappellani et al., 2014; Daams et al., 2013; Calabrese et al., 2011; Ceccarelli et al., 2010; Neema et al., 2009; Geurts et al., 2005; Popescu and Lucchinetti, 2012; Popescu et al., 2013; Lucchinetti et al., 2011; Kutzelnigg and Lassmann, 2006; Romme Christensen et al., 2013) .

Further support for the role of B cells in the immunopathology of MS is provided by the data of the efficacy of B-cell-and antibody-directed therapies (i.e., plasmapheresis and anti-CD20 monoclonal antibodies), in subgroups of MS patients Weinshenker et al., 1999; Kappos et al., 2011; Hauser et al., 2008) . The involvement of antibody-mediated pathogenetic mechanisms is particularly pronounced in variants of CNS demyelinating disease, such as neuromyelitic types of MS (neuromyelitis optica (NMO) spectrum of disorders) associated with anti-aquaporin antibodies and long magnetic resonance imaging (MRI) lesions in the cervical spine.

Normal motor and sensory function depend upon the rapid propagation of the nerve impulse along myelinated nerve fibers, measured in milliseconds. The myelin sheath is interrupted at regular intervals by the nodes of Ranvier, where the axon is denuded. Because the axon has a high resistance to the electrical impulse, which makes the speed of conduction too slow, an alternative mechanism takes over. It is called 'saltatory conduction,' in which the electrical impulse jumps from one node of Ranvier to the next while achieving the required conduction velocity. However, if the distance between the available nodes is too great because of destruction of some myelin segments, the impulse cannot bridge the gap, and saltatory conduction is no longer possible. The electrical impulse must then travel via the slow axonal route (Figure 3b ). Once the axon itself is destroyed, conduction is obviously no longer possible and the deficit, if any, becomes permanent. In some MS patients, signs or symptoms appear because nerve conduction slows when body temperature is elevated as a result of either ambient heat or fever. The latter is a common cause of pseudo-exacerbations. A body temperature increase of as little as 1 C may be sufficient to cause such signs and symptoms, which disappear upon cooling. In the past, this was used diagnostically by means of the hot bath test.

Several clinical types have been recognized: relapsing-remitting, primary, and secondary progressive (RRMS, PPMS, and SPMS, respectively) (Karussis, 2014; Lublin, 2014) .

Some investigators believe that these clinical types represent different diseases or genetic variants of MS, but it is much more likely that the differences in evolution indicate the aggressivity of the disease process, the patient's susceptibility, and the accumulation of lesions in eloquent areas of the CNS. Many MS lesions remain silent, and a number of routine autopsy series have shown that asymptomatic MS may be as common as the diagnosed condition, with a putative prevalence of 100/100 000.

It is frequently perceived that PPMS is less 'inflammatory' and progresses slower (Miller and Leary, 2007) . However, epidemiological data show that when RR disease turns to progressive disease (i.e., SPMS), which usually takes a median of two decades from onset (Tremlett et al., 2008) , the rate of progression does not differ substantially from that of PPMS (Koch et al., 2009 (Koch et al., , 2015 Harding et al., 2015; Confavreux and Vukusic, 2006) .

It is more acceptable nowadays that there is no clear demarcation between relapsing and progressive disease and there are also mixed courses of relapsing-progressive MS (RPMS). It will be more accurate to define progressive disease as either active/ 'inflammatory' (i.e., with evidence of relapses or changes in the MRI) or nonactive/'degenerative' (Lublin, 2014) .

In general, negative prognostic factors for MS predicting progression to higher levels of disability, include: the early transformation to SPMS, a higher relapse rate and disability in the first 5 years, a shorter interval between the first and the second relapse, and the early involvement of more neurological systems (Degenhardt et al., 2009; Vukusic and Confavreux, 2007) .

The symptoms of MS at onset in six series, in three of which the diagnosis was confirmed at autopsy. The disease is almost twice as common in women as in men, and the clinical onset is most frequent in the third and fourth decades. Certain neurological complaints in a person under the age of 40 are tantamount to making the diagnosis of MS: a Lhermitte symptom (tingling going down the back when flexing the neck), trigeminal neuralgia, hemifacial spasms, unilateral intention tremor, or binocular diplopia. Similarly, certain abnormalities of the neurological examination of a young person are also common enough in MS to be of diagnostic value: temporal pallor of the optic disk, unilateral hyperreflexia and a Babinski sign, a significant decrease in position and/or vibratory sensation at the ankles, or some dysmetria on finger-to-nose testing and internuclear ophthalmoplegia. MS patients may also experience rarer symptoms such as headaches, positional vertigo, seizures, back and neck pain, and significant cognitive decline. The latter was thought to be very rare since the disease does not affect the gray matter. However, it is now well documented that there is significant involvement of the gray matter in MS, and cognitive impairment is frequent even at the early stages of the disease (DeLuca et al., 2015; Langdon, 2011; Chiaravalloti and DeLuca, 2008; Cardoso et al., 2015) but often overseen/underdiagnosed. Patients with the so-called 'benign' MS (representing less than 10% of the patients, and defined by the absence of relapses or progression of disability for more than 10 years) actually do have significant silent activity and cognitive impairment (usually affecting concentration and memory in up to 50%) (Gajofatto et al., 2015; Correale et al., 2012; Amato et al., 2006; Sayao et al., 2011; Rovaris et al., 2008) and structural brain damage, similar to the nonbenign MS.

The diverse and variable clinical expressions and signs of MS are quantified by using scales of disability, the most universally accepted over years, being the expanded disability status scale (EDSS) initially proposed by Kurtzke (1983) and revised over the years. EDSS steps 1.0-4.5 refer to people with MS who are able to walk without any aid and are based on measures of impairment in eight functional systems (FS). EDSS steps 5.0-9.5 are defined by the impairment to walking. The scale is criticized for its reliance on walking as the main measure of disability and the lack of linearity.

The Multiple Sclerosis Functional Composite (MSFC) is a newer measurement system. It is sensitive to changes other than mobility, and it is based mainly on three parameters: walking speed, using a timed 25-foot walk, arm and hand dexterity, using a nine-hole peg test and cognitive function, and using the Paced Auditory Serial Additions Test (PASAT) (Rudick et al., 2002) . A wide range of other measures is used to assess MS disability. In many cases, these are simple questionnaires, such as the MS Quality of Life and the fatigue scale questionnaires.

True exacerbations/relapses appear spontaneously or may follow some kind of viral infection but must be differentiated from pseudo-exacerbations that result from fever, elevated ambient temperature, or some metabolic derangement.

The correlation between the number, site, and size of MS lesions, as revealed by neuroimaging and at autopsy, and clinical manifestations is poor. Many plaques involve the so-called 'silent' areas of the brain. Furthermore, the disease process must impair conduction in a critical number of fibers in order to produce neurological dysfunction. The available fibers in the affected tract above this number constitute the safety factor. If the signs and symptoms are due to inflammation and edema only, which is almost always the case at the onset of a bout, they will be reversible; it is only when the safety factor is breached, that is, when the number of demyelinated or destroyed fibers exceeds the required minimum, that signs and symptoms become permanent.

Several variants of MS (and CNS demyelinating syndromes in general) have been nowadays defined (Karussis, 2014) in an effort to increase the diagnostic accuracy, to identify the unique immunopathogenic profile (Table 2) , and to tailor treatment. These include the initial events of demyelination defined as clinically or radiologically isolated syndromes (CIS and RIS, respectively) (Okuda et al., 2009; Miller et al., 2005a,b) , ADEM (Brinar and Habek, 2010; Menge et al., 2007) and its variants (acute hemorrhagic leukoencephalitis -AHL, Marburg variant, and Balo's (Brinar and Habek, 2010) concentric sclerosis) (Zettl et al., 2012; Kuperan et al., 2003; Mader et al., 2004; Susac and Daroff, 2005) , Schilder's sclerosis (Zettl et al., 2012) and transverse myelitis (Poser et al., 1986) , neuromyelitis optica (NMO and NMO spectrum of diseases) (Wingerchuk and Weinshenker, 2013) , recurrent isolated optic neuritis (Zettl et al., 2012) , and tumefactive demyelination (Lucchinetti et al., 2008 ) (a large, tumor-like demyelinating lesion with surrounding edema) ( Table 2 ). The differentiation between them is not only a terminological matter but has important implications on their management. For instance, patients with type-II MS immunopathogenesis (according to Luccinetti's classification (Lucchinetti et al., 2000) , where autoantibodies seem to be more involved than T cells, or with the neuromyelitic variants of demyelination (NMO spectrum of diseases, associated with anti-aquaporin antibodies) (Wingerchuk and Weinshenker, 2013; Wingerchuk et al., 2006 Wingerchuk et al., , 2007 Wingerchuk, 2010; McKay et al., 2006) , may not only not respond well but also even deteriorate under some of the first-line treatments for MS (such as IFNs) (Bomprezzi et al., 2011) . The unique clinical and neuroradiological features ( Table 2) , along with the use of immunological biomarkers (such as anti-AQP4 antibodies), help to distinguish these cases from classical MS. The use of such immunological and imaging biomarkers will not only improve the accuracy of diagnosis but also contribute to the identification of the patients with CIS or RIS, who are at greater risk for disability progression (worse prognosis) or, on the contrary, will have a more benign course.

The original diagnostic criteria for MS were based on clinical features suggestive of CNS demyelination. The oldest Schumacher criteria called for two clinical relapses separated in time and space in patients aged 10-50 years and with no better explanation for their signs and symptoms (Schumacker et al., 1965) . The subsequent Poser criteria added to the Schumacher definition laboratory/paraclinical parameters for the diagnosis (the presence of oligoclonal bands -OCBsin the CSF and of abnormal/delayed responses of the visual and auditoryevoked potentials) (Poser et al., 1983 ; Table 3 ). The crucial request in both criteria, in order to definitely diagnose MS, was the need for clinical (or laboratory) evidence of dissemination in time and space (DIT/DIS), that is, the presence of symptoms affecting more than one discrete CNS region and at more than one time point during the course of the disease. Patients were accordingly subclassified as clinically definite (CDMS) or probable and laboratory-supported definite or probable MS (Table 3) .

With the advance of neuroradiological techniques (MRI), the need for clinical evidence of DIT and DIS was partially replaced by the radiological evidence of such dissemination. Based on this principle, a committee headed by McDonald defined the new proposed criteria (McDonald et al., 2001) , which were later revised .

In general, the McDonald criteria focus on the integration of clinical, laboratory, and radiographic data to establish a diagnosis of MS. Similar to the Poser criteria, the 2001 McDonald diagnostic criteria require two clinical attacks varying in time and space to establish a definite diagnosis of MS. DIT could be fulfilled by either gadolinium (Gd)enhancing lesion, or a new T2 lesion detected on repeat MRI scanning performed 3 or more months after the baseline study. DIT required either meeting the Barkhof/Tintore MRI criteria (3 of the 4 criteria: !1 Gd-enhancing or 9 T2 lesions, !1 juxtacortical, !1 infratentorial, and !3 periventricular lesions) (Barkhof et al., 1997; Tintore et al., 2003) or the presence of two silent T2-weighted brain lesions and OCBs in the CSF. The sensitivity and specificity of the 2001 McDonald criteria for prediction of conversion to MS in 1-3 years were high and could therefore establish the diagnosis of MS after CIS earlier than the Poser criteria, more than doubling the rate of MS diagnosis within the first year of disease Dalton et al., 2002) . The revised 2005 criteria better underlined the significance of spinal cord lesions for DIS criteria and allowed new T2-weighted lesions on brain MRI after 30 days (rather than the previous time frame of 3 months) following the baseline MRI to establish DIT . These updated criteria led to an improvement in sensitivity compared with the 2001 criteria (60% vs 47%), while retaining good specificity (88% vs 91%) (Swanton et al., 2007) .

The McDonald criteria were revised in 2010 with the intent of further simplification , requiring fewer MRI scans to establish the diagnosis of definite MS. To meet the criteria for DIS, a patient must have two clinical attacks in different CNS sites or one clinical attack accompanied by fulfillment of Swanton's radiographic criteria. Symptomatic MRI lesions in the brain stem or spinal cord are excluded from the lesion count for these MRI criteria. Gd enhancement is not necessary for DIS. According to the 2010 criteria, DIT requires a new T2-or Gd-enhancing lesion on subsequent MRI (regardless of timing from baseline scan) or the presence of both asymptomatic Gd-enhancing lesions and nonenhancing lesions on the baseline MRI (Table 3) . Thus, the diagnosis of MS after one clinical attack may now be established even based solely on the baseline MRI (if both enhancing and nonenhancing lesions coexist). CSF findings do not replace the radiographic requirements for DIS according to the McDonald 2010 criteria. These revised criteria are considered to have increased diagnostic sensitivity without compromising specificity. (Miller et al., 2005b) .

In 85% involves the optic nerves, brain stem, or spinal cord. Multifocal brain lesions are present on MRI in many patients with CIS; some have additional abnormalities on quantitative MRI in otherwise normal appearing white and gray matter that suggest an extensive pathological process (Miller et al., 2005b) .

Chronic, multifocal demyelinating disease of the CNS with clinical and/or radiological evidence of dissemination in time and space.

Usually relapsing course (RRMS); in 60-80% of the cases the course becomes progressive with time (SPMS). Primary progressive (prevalence 10%), relapsingprogressive, and benign forms also exist. The median time from diagnosis of RRMS to SPMS is 10 years, and the time from disease onset to requiring a cane to walk is 15-25 years. More than 80% of the patients (40-50% in the first year of the disease) have oligoclonal antibodies in the CSF (which is typically acellular and with normal protein levels). Brain MRI pathological in 95% of the patients. Visual and/or brain stem-evoked potentials pathological in 60-70%. ADEM

A first ever clinical event with presumed inflammatory or demyelinating cause, with an acute or subacute onset affecting multifocal areas of the CNS. This is usually polysymptomatic and includes encephalopathy, more common in children (Menge et al., 2007; Caldemeyer et al., 1994; Dale et al., 2000; Mikaeloff et al., 2007; Murthy et al., 2002; Tardieu and Mikaeloff, 2004) .

Presence of focal/multifocal lesion(s) predominantly affecting the white (but also the gray) matter, without evidence of previous destructive white matter changes, the occurrence of clinical/radiological improvement (although there may be residual deficits), and the absence of other etiology that could explain the event. New or fluctuating symptoms, signs, or MRI findings occurring within 3 months are considered part of the initial acute event. Lack of oligoclonal antibodies and the presence of several lymphocytes in the CSF; early involvement of CNS gray matter areas; lack of significant dissemination in space (in the case of relapsing ADEM; usually only expansion of previously existing lesions occurs); presence of fever, confusion, and headache (Menge et al., 2007) .

Presents with at least one large (>2 cm) acute demyelinating lesion, with accompanying edema, mass effect, and ring enhancement. Clinical presentations vary by size and location of the lesion and often include headache, confusion, aphasia, apraxia, and seizures (which are atypical of CIS/MS) (Lucchinetti et al., 2008) .

(Continued) (Zettl et al., 2012; Susac and Daroff, 2005) .

Marburg: Numerous large multifocal demyelinating lesions in deep white matter. Balo: Concentric layers of partial demyelination alternating with bands of demyelination. Alternating isointense and hypointense concentric rings on T1-weighted images in MRI, partial enhancement limited to T1-hypointense areas. Schilder's disease Myelinoclastic diffuse sclerosis, usually characterized by a single or two symmetrically arranged lesions measuring at least 2 Â 3 cm with involvement of the centrum semiovale in setting of symptoms unusual for MS (Zettl et al., 2012; Poser et al., 1986) .

Absence of OCBs in CSF.

Acute hemorrhagic leukoencephalitis (AHL), acute hemorrhagic leukoencephalomyelitis (AHEM), and Hurst acute necrotizing hemorrhagic leukoencephalitis (ANHLE)

Rare, severe, rapidly progressive inflammatory and hemorrhagic demyelinating disorders of the CNS, considered variants of ADEM (Kuperan et al., 2003; Mader et al., 2004; Rosman et al., 1997; Wong et al., 2006) .

White matter lesions on MRI tending to be large and diffuse, with edema and mass effect, as well as restricted diffusion in affected areas of the brain. CSF typically demonstrates elevations in WBCs, red blood cells, and protein.

Neuromyelitis optica (NMO) Episodes of optic neuritis (often severe and bilateral leading to fixed visual loss) and acute myelitis are the major criteria for diagnosis and a contiguous spinal MRI lesion extending over !3 vertebral segments or NMO-IgG seropositive are secondary criteria for diagnosis. According to the modified criteria, brain lesions may also be present in NMO. CSF can show pleocytosis of >50 WBCs. The longitudinally extensive myelopathy usually affects the central part of the cord, and intractable hiccups, nausea, or vomiting may be reported as a result of a periaqueductal medullary lesion (Wingerchuk and Weinshenker, 2013; Wingerchuk et al., 2006; McKeon et al., 2009 (1965) Clinical signs of problem in CNS Evidence of two or more areas of CNS involvement Evidence of white matter involvement One of these: Two or more relapses (each lasting ! 24 h and separated by at least 1 month) or progression (slow or stepwise) Patient should be between 10 and 50 years of age at the time of examination No better explanation for patient's symptoms and signs Poser's criteria (1983) 1. CDMS (clinically definite MS): Two or more attacks (relapses), with clinical (neurological dysfunction demonstrable by neurological examination) or paraclinical evidence. (Demonstrable by any test of the existence of a nonclinical lesion in the CNS); at least one event should be of clinical evidence 2. LSDMS (laboratory-supported definite MS): At least one attack and oligoclonal bands. (1) Two attacks (occurrence of a symptom of neurological dysfunction for more than 24 h), and evidence (clinical or paraclinical) along one of the following lines;

(2) one attack and two clinical manifestations; (3) New criteria: One year of disease progression (retrospectively or prospectively determined) and two or three of the following: 1. Evidence of DIS in the brain based on one or more T2 lesions in the MScharacteristic regions (periventricular, juxtacortical, or infratentorial) 2. Evidence of DIS in the spinal cord based on two or more T2 lesions in the cord 3. Positive CSF (isoelectric focusing evidence of oligoclonal bands and/or elevated IgG index)

MRI can support the investigation, diagnosis, and management of patients with MS, but the association between conventional neuroradiological markers and clinical disability of MS is weak, a phenomenon referred to as the clinico-radiological paradox (Miller et al., 1998) . Reasons for this poor association include the emphasis of MRI protocols only on the detection of focal white matter pathology, the limited sensitivity of the EDSS score to detect small degrees of clinical deterioration, and the inability of the routine MRI techniques to provide an accurate estimation of degeneration, axonal damage, and compartmentalized inflammation (i.e., in the meninges or in the cortical and deep gray matter) (Ruggieri et al., 2015; Haider et al., 2014; Cappellani et al., 2014; Daams et al., 2013; Calabrese et al., 2011; Neema et al., 2009; Magliozzi et al., 2007; Ceccarelli et al., 2010; Geurts et al., 2005; Popescu and Lucchinetti, 2012; Popescu et al., 2013; Kutzelnigg and Lassmann, 2006; Serafini et al., 2004; Lucchinetti et al., 2011; Romme Christensen et al., 2013) . T1 hypointense lesions ('black holes') seem to correlate better with measures of disability than T2 lesion number and volumes (Venken et al., 2010) . Contrast-enhancing lesions indicate acute inflammation; such enhancement is transient, typically lasting about 6-8 weeks (Venken et al., 2010; Lucchinetti et al., 2000) . Another confounding factor for this clinico-radiological dissociation is the heterogeneity of lesions in MS and the involvement of the 'normally appearing white and gray matter.' Correlations between clinical parameters and imaging are improved with the use of novel neuroimaging techniques such as magnetization transfer imaging, functional MRI, or diffusion tensor MRI (Rovira et al., 2015; Wattjes et al., 2015) , but these techniques still do not have a central role in monitoring disease evolution in the everyday practice.

The increasing use of such MR protocols may provide a better insight into the disease activity, which, in turn, can be used to inform prognosis and guide treatment decisions.

Nowadays, MRI is a critical tool for both the diagnosis of early MS (McDonald criteria) and the prediction of its future course. It can detect clinically silent activity of MS, better than the clinical history or neurological examination alone (Rudick and Cutter, 2013) . Up to 70% of brain lesions (Jacobs et al., 1986; Ormerod et al., 1987) and 30% of spinal lesions (Dalton et al., 2004; O'Riordan et al., 1998) develop without clinical evidence of relapse. New silent lesions (that may be defined as 'radiological relapses') appear up to 10 times more frequently than lesions associated with clinical relapses (Wingerchuk et al., 2006; Isaac et al., 1988; Kappos et al., 1988) . More than half of CIS patients show one or more clinically silent T2-bright abnormalities on their baseline brain MRI (Miller et al., 2005b; O'Riordan et al., 1998; Brex et al., 2002; Frohman et al., 2003) , the presence and the number of which may predict the risk of development of MS in the next 5-14 years (O'Riordan et al., 1998; Kappos et al., 1988; Ghezzi et al., 1999; Miller et al., 1988; Morrissey et al., 1993) .

The standard brain MRI protocol for MS includes a threeplane scout, sagittal fast FLAIR, axial fast spin echo proton density/T2, axial fast FLAIR, and axial Gd-enhanced T1, as recommended by the Consortium of Multiple Sclerosis Centers (CMSC) to evaluate patients presenting with possible CIS . The CMSC guidelines also recommend spinal cord MRI in patients presenting with symptoms at the spinal cord level or in patients with focal neurological signs and an equivocal brain MRI.

The results of numerous studies assessing the risk of conversion from CIS to CDMS suggest that patients who have asymptomatic brain MRI lesions at the time of presentation of CIS have a 60-80% chance of developing CDMS within 10 years, whereas those without brain lesions carry a much lower risk ($20% risk) Frohman et al., 2003; Beck et al., 2003; Minneboo et al., 2004; Scott et al., 2005) . In general, the number of lesions seems to be well correlated with the risk of conversion to CDMS.

MRI parameters that may predict conversion to CDMS include:

1. The presence of multifocal homogenous or ring-enhancing white matter lesions. 2. T2-hyperintense lesions in the corpus callosum (Zivadinov and Cox, 2007) . 3. T2-hyperintense lesions in the posterolateral compartment of the spinal cord (Cordonnier et al., 2003) . 4. Positivity for Barkhof criteria (i.e., at least nine T2 lesions or at least one contrast-enhancing, the presence of an infratentorial lesion, the presence of a juctracortical lesion, at least 3 periventricular; three out of four may suffice (Barkhof et al., 1997) ).

However, particularly in the very early stages of MS, the sole use of MRI may introduce diagnostic errors due to low specificity. Hyperintense lesions in the white matter of the CNS (sometimes defined also as UBOs-unknown bright objects) can be detected in a plethora of pathological conditions (including migraine, microvascular disease, and various connective tissue diseases) or even in a small percentage of 'healthy' individuals (Kruit et al., 2004; Morris et al., 2009; Vernooij et al., 2007) . This is the reason why the old diagnostic criterion introduced in the 1960s by Shumacker ('rule out other possible causes'), still appears in the 2010 revised criteria by McDonald and in the recent criteria for RIS, stressing the need for analysis of the MRI data with care and performance of a thorough differential diagnosis.

Conventional 1.5 T imaging does not capture the entire extent of MS activity. For example, cortical lesions, that may exist in nearly 40% of patients with early MS Lucchinetti et al., 2011; Calabrese et al., 2010a) , cannot be captured by conventional imaging but only with double inversion recovery imaging (Calabrese et al., 2007; Nelson et al., 2007) and/or using a 7 T MRI machine (Hasan and Narayana, 2009; Hammond et al., 2008; Kangarlu et al., 2007; Mainero et al., 2009) . The presence of at least one cortical lesion in patients with CIS may help identify those at high risk for conversion to CDMS Calabrese et al., 2010b; Filippi et al., 2010) .

Small studies using additional and more advanced MR techniques such as magnetic resonance spectroscopy (MRS) and magnetization transfer imaging (MTI) have shown that these methods can contribute to the prediction of conversion from CIS patients to CDMS (Wattjes et al., 2008a,b; Filippi et al., 2000; Iannucci et al., 2000) . Standardization of protocols and improvements in technology (e.g., software) seem to be essential in order that MRI will be used routinely to monitor time-based changes in brain volume (atrophy measure) (Venken et al., 2010; Lucchinetti et al., 2000) .

Visual-evoked potentials (VEPs) are abnormal in 30% of patients with CIS, regardless of clinical symptoms (Rot and Mesec, 2006) and in >50% of patients with MS (Bradley et al., 2008) who have no history or clinical evidence of optic nerve dysfunction. Somatosensory-evoked potentials (SSEPs) and brain stem auditory-evoked potentials (BAEPs) may also be used as evidence of demyelination that is nondetectable clinically or on MRI. It was shown (Pelayo et al., 2010) that if all three evoked potentials (VEP, SSEP, and BAEP) are abnormal at the time of CIS, there is an increased risk of developing moderate disability from MS that is independent of MRI findings.

About 60-70% of patients with CIS and up to 90% of those with MS have two or more immunoglobulin G (IgG) oligoclonal bands (OCBs) uniquely to the CSF (Miller et al., 2005b; Avasarala et al., 2001; Awad et al., 2010; Paolino et al., 1996; Polman et al., 2008; Sastre-Garriga et al., 2003; Tintore et al., 2001; Zipoli et al., 2009) . CSF OCB testing must be run in parallel with sampling of serum obtained within 72 h of the lumbar puncture. The preferred method of analysis with the highest sensitivity and specificity for MS is isoelectric focusing on agarose gels, followed by immunodetection by blotting or fixation (Freedman et al., 2005) . Some 70-90% of MS patients will have an elevated IgG index (Awad et al., 2010) and (Link and Huang, 2006) , and this may be in conjunction with, or independent of, the presence of OCB in the CSF. The presence of !2 OCBs in the CSF has a positive predictive value of 97%, a negative predictive value of 84%, a sensitivity of 91%, and a specificity of 94% for developing relapsing-remitting MS (RRMS) after a CIS (Masjuan et al., 2006) . The presence of OCBs within 3 months of CIS (Tintore et al., 2008) nearly doubles the risk of a second clinical attack over 4-6 years (Martino et al., 2005) . On the other hand, CSF with >50 white blood cells (WBCs) mm À3 or >100 mg dl À1 protein is rarely observed in MS, and this should raise the possibility of an alternative diagnosis (McDonald et al., 2001; Trapp and Nave, 2008) . It is also important to bear in mind that disorders other than MS may also be associated with the presence of OCB and a high IgG index. The differential diagnosis for the presence of OCBs in the CSF includes the Sjogren's syndrome (75-90% of patients with neurological involvement), neurosarcoidosis (40-70%), systemic lupus erythematosus (30-50%), Behcet disease (20-50%), paraneoplastic disorders (5-25%), antiglutamic acid decarboxylase antibody syndromes (40-70%), Vogt-Koyanagi-Harada syndrome (30-60%), Hashimoto's steroid-responsive encephalopathy (25-35%), subacute sclerosing panencephalitis (100%), rubella encephalitis (100%), neurosyphilis (90-95%), neuroborreliosis (80-90%), human immunodeficiency virus infection (60-80%), meningitis (5-50%), adrenoleukodystrophy (100%), ataxia telangiectasia (50-60%), Leber hereditary optic atrophy (5-15%), CNS vascular disorders (5-25%), and CNS tumors (<5%) (Awad et al., 2010) .

As MS pathogenesis involves mainly immune-mediated mechanisms, serum immune biomarkers are good candidates for the diagnosis and prognosis of the disease, reflecting the presence, nature, and intensity of certain immune responses (Hawa et al., 2004) . Also, from a practical standpoint, tests for serum biomarkers could prove very useful, as blood is relatively simple to collect and the tests can be easily repeated as a monitoring strategy (Schwarz et al., 2006; Freedman et al., 2009; Brettschneider et al., 2009) . Such biomarkers may also be identified in the CSF, which is in closer proximity to the lesions in the CNS.

Biomarkers in conjunction with other prognostic criteria, such as MRI, may help in the early identification of MS and stratify CIS patients according to their risk for progression to CDMS. Such classification rules may provide additional tools for the determination of the most appropriate treatment strategy for the individual patient (Rudick and Polman, 2009; Rudick et al., 1997; Jacobs et al., 2000; Kappos et al., 2007) .

Antibodies targeting myelin antigens are, naturally, one of the most extensively studied serum biomarkers in MS. The presence of IgM, against the extracellular domain of myelin oligodentrocyte protein (MOG), together with antibodies specific for myelin basic protein (MBP), (which are two of the main immunogenic antigens in the CNS myelin sheath) in CIS patients, was shown to be highly predictive for CDMS (Berger et al., 2003; Tomassini et al., 2007) . However, other studies testing the prognostic value of anti-MOG and anti-MBP antibodies revealed controversial results ranging from highly significant to totally insignificant (Berger et al., 2003; Tomassini et al., 2007; Kuhle et al., 2007a,b; Pelayo et al., 2007) .

Antibodies targeting alpha glucose-based antigens were found to differentiate MS from other neurological diseases and to predict progression to a more severe disease phenotype (Schwarz et al., 2006; Freedman et al., 2009; Brettschneider et al., 2009 ). More recently antibodies against a novel astrocyte target, the potassium channel KIR4.1 protein, have been found to be associated with MS (Srivastava et al., 2012; Brill et al., 2015) . However, such association has not been universally confirmed by additional groups and remains controversial (Brickshawana et al., 2014) .

The B-cell chemoattractant chemokine CXCL13 was also shown to serve as a prognostic marker for conversion to CDMS in patients with CIS, especially when combined with the Barkhof MRI criteria (Festa et al., 2009; Alvarez et al., 2013; Ferraro et al., 2015; Khademi et al., 2011) .

Additional novel biomarkers for MS include osteopontin, TNFa, various cytokines and chemokines, and a b-crystallin. Neurofilament protein subunits have been lately in the focus of interest as prognostic biomarkers. Their presence at high levels in the CSF may reflect acute axonal damage and imply a prognostic value for conversion from CIS to CDMS (Teunissen and Khalil, 2012; Teunissen et al., 2009; Fialova et al., 2013a,b) .

Logically, based on this widely accepted model for MS immunopathogenesis described previously (Tables 2 and 3; Figure 3a ), the therapeutic approaches to the disease include modalities aimed at downregulating the various immune elements that are involved in the immunological cascade (Karussis, 2013) . Since the introduction of IFNs in 1993, which were the first registered immunotherapies for MS, huge steps have been made in the field of MS immunotherapy. The novel, at that time, concept of 'immunomodulation' (referring to a specific downregulation of the pathogenic immune cells through induction of a shift of the immune response or enhancement of the intrinsic regulatory immune networks), as opposed to generalized immunosuppression, was initially introduced from the studies with IFNs and linomide, in the early 1990s (Abramsky et al., 1996; Karussis et al., 1993a Karussis et al., , 1996 .

During the last two decades, since the advent of IFN and Copaxone, more target-focused immunoactive drugs have been introduced and it appears that these new treatments are more efficacious (Figure 4) . However, this seemingly increased efficacy of the new immunomodulatory drugs has to be carefully interpreted as the clinical trials during the last decade included MS patients with a lower relapse rate, and this fact complicates the comparisons between old and new generation drugs. In addition, more safety issues have arisen with these new immunomodulators (Figure 4) .

Since, neurodegeneration evolves early andprobablyas a consequence of inflammation, early immune intervention is warranted to prevent not only the relapses of the disease but also the accumulation of disability and future irreversible damage. The use of neuroimaging (MRI) techniques that allow the detection of silent inflammatory activity and neurodegeneration has provided an important tool for the substantiation of the clinical efficacy of treatments and the early diagnosis of MS. The introduction of new diagnostic criteria (McDonald et al., 2001) for CDMS does not necessitateas in the past yearsthe occurrence of a second clinical relapse, but only the dissemination in time and space, reflected by MRI dynamic changes. This has paved the path to the concept of early immunotherapy in selected patients experiencing the first demyelinating episode (CIS), or even (theoretically) in individuals with a sole neuroradiological evidence of demyelination (RIS). However, the prognosis of MS is highly variable and therefore additional clinical, radiological, and immunological surrogate biomarkers should be used to define those cases with a bad prognosis in which early immunotherapy at the stage of CIS or RIS may be justified.

The immunotherapeutic modalities can be divided into two main groups: those affecting the acute phase (relapse) of the disease and the long-term preventive treatments. Immunomodulating treatments may also be classified according to the level of the 'immune axis' where they exert their main effect (Figure 3a ; Tables 4 and 5).

Based on their molecular construction and their basic mechanism of action, immunotherapeutic agents may also be classified as (1) cytotoxic drugs; (2) synthetic immunomodulators;

(3) monoclonal antibodies; (4) vaccines (T-cell vaccines, antigen vaccines); (5) oral tolerizing agents; (6) modalities that act as indirect immunosuppressants (plasmapheresis, intravenous immunoglobulins -IVIG); and (7) cellular therapies (stem cells, progenitors).

The most widely used treatment, during an acute MS relapse, is methylprednisolone or other corticosteroid preparations. Figure 4 The spectrum of various immunotherapies in MS: Newer modalities have seemingly increased efficacy and specificity but also more safety issues. Reprinted with permission from Poser, C., 1998. An Atlas of Multiple Sclerosis. Parthenon Publishing Group, London. Fig. 44 , p. 70.

Description of the mechanisms of action of immunotherapeutic agents in MS and their Class evidence of efficacy

Basic mechanism of action Class evidence of efficacy in MS Corticosteroids l Induction of lipocortin-1 (annexin-1) synthesis, with resulting diminished eicosanoid production l Suppression of cyclooxygenase (COX-1 and COX-2) expression l Inhibition of genes affecting production of cytokines Interleukin 1 (IL-1), IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IFNg, TNFa, resulting in T-cell inhibition l Down-regulation of antibody production l Down-regulation of adhesion molecules expression l Reduction of blood-brain barrier (BBB) permeability In high supraphysiological doses, glucocorticoids strongly downregulate inflammation. They suppress cellular immunity by inhibiting genes that affect the production of various cytokines and TNFa and by reducing the proliferative ability of T cells (Rose et al., 1970; Abbruzzese et al., 1983b; Barkhof et al., 1991; Beck et al., 1992; Miller et al., 1991) . Glucocorticoids also suppress humoral immunity, causing B cells to express smaller amounts of IL-2 and IL-2 receptors, thus diminishing their expansion and antibody production.

Steroids reduce the permeability of the blood-brain barrier Miller et al., 1992; Kesselring et al., 1989) Description of the mechanisms of action of immunotherapeutic agents in MS and their Class evidence of efficacydcont'd

Cyclo-phosphamide l A nitrogen mustard alkylating agent from the oxazophorine group with broad cytotoxic and immunosuppressive effects; its main metabolite phosphoramide mustard is only formed in cells with low aldehyde dehydrogenase (ALDH) levels. l Formation of DNA crosslinks at guanine positions, leading to cell death l Suppression mostly of B cells l Suppression of T cells and IFNg and IL-12 cytokine production l Increase in IL-4 and IL-10 production and induction of a Th2 shift Corticotropin (aka adrenocorticotropic hormone, ACTH) hastens recovery at 1 month after treatment (Rose et al., 1970) . Comparable or superior results were shown with methylprednisolone (Abbruzzese et al., 1983a,b; Barnes et al., 1985; Thompson et al., 1989) . Data from the Optic Neuritis Treatment Trial showed that intravenous methylprednisolone is superior to oral prednisone for the treatment of acute optic neuritis (Beck, 1988 (Beck, , 1995 . However, the long-term effect of both treatment regimens on the visual acuity was marginal and there was no significant 'protection' against later development of definite MS (Beck et al., 1992 (Beck et al., , 1993 . A review of the trials with either intravenous methylprednisolone or ACTH showed a clear benefit of steroids in MS exacerbations (Filippini et al., 2000) .

In patients with chronic progressive MS, steroids showed a milder effect. Two studies have shown a short-term improvement following high-dose intravenous methylprednisolone (Cazzato et al., 1995) or a long-term beneficial effect by 4-monthly intravenous methylprednisolone boosts which slowed the development of T1 black holes and delayed wholebrain atrophy and disability progression (Zivadinov et al., 2001) .

Despite these data and the documented transient beneficial effect during the acute MS relapse, steroids do not seem to significantly alter the natural course of the disease and their chronic use does not seem justified. In addition, chronic steroid administration is associated with several adverse effects including osteoporosis, aseptic bone necrosis, hypertension, hyperglycemia, cataracts, and psychotic events.

Despite wide agreement on the efficacy of steroidal treatment in MS relapses, the optimal protocol for administration of the drug is still not settled. Current protocols (mostly empirical) include 3, 5, or even 10 days of 1-2 g intravenous methylprednisolone with or without oral tapering with prednisone. Oral administration of high-dose methylprednisolone appears to be equally efficient to intravenous administration (Alam et al., 1993; Sellebjerg et al., 1998; Martinelli et al., 2009 ). There are indications, not based on published studies in MS but on experience in other autoimmune diseases (such as systemic lupus erythematosus -SLE), that abrupt discontinuation of intravenous steroidal treatment in MS relapses may increase the risk of a recurrence of the symptoms. Therefore, a tapering-off protocol following high-dose intravenous methylprednisolone appears preferable. 2. Levels B and D: Activation and proliferation/expansion of the autoimmune, myelin reactive lymphocytes: Chemotherapeutic/cytotoxic agents (azathiorpine, cyclophosphamide, methotrexate, cyclosporine, mycophenolate, cladribine, mitoxantrone, tarcolimus, teriflunomide); immunoablation and resetting of the immune system by hematopoietic stem cell transplantation; Lymphocyte depletion with monoclonal antibodies (alemtuzumab, rituximab, daclizumab); specific reduction of autoimmune myelinresponsive lymphocytes with vaccination techniques (i.e., T-cell vaccination, myelin peptides vaccination).

3. Levels C and D: Regulatory cells or immunological shift: IFNb, GA, laquinimod, fingolimod, alemtuzumab, teriflunomide, cyclophosphamide. 4. Level E: B cells and antibodies/humoral immunity: plasmapheresis, IVIG, anti-CD20 monoclonal antibodies, steroids, cytotoxic drugs (azathiorpine, mycophenolate, cyclopshosphamide), alemtuzumab. 5. Levels B and G: Cytokine production: various immunosuppressants, corticosteroids, IFNb, GA, fingolimod, teriflunomide, cyclosporine-A, laquinimod, cyclophosphamide, azathioprine, alemtuzumab. 6. Level F: Migration or homing of the lymphocytes and entrance through the blood-brain barrier: fingolimod, natalizumab, corticosteroids. ?, questionable effect; þ, Mild effect; þþ, moderate effect; þþþ, strong effect; À, negative effect; þ/À, borderline effect.

Plasmapheresis, also known as therapeutic plasma exchange (PLEX), is a procedure that separates the blood components, exchanging the plasma (typically with donor plasma or albumin), and returning the other components, primarily red blood cells, to the patient. PLEX is known to be effective in various autoimmune diseases.

Since the late 1980s, PLEX has been tried in several studies on MS patients, but with inconsistent effects. This may be related to (1) the small size of the studies, (2) the lack of homogeneity in the treatment protocols, (3) the use of PLEX as an adjuvant therapy to other immunomodulatory modalities, and (4) the patient populations and type/course of MS, which greatly varied among these studies (Khatri et al., 1991; The Canadian Cooperative Multiple Sclerosis Study Group, 1991; Noseworthy et al., 1991; Weiner et al., 1989) .

In a more recent and randomized trial, which represented the revival of PLEX as a treatment modality for MS, PLEX was for the first time checked as a single modality in patients with various types of acute CNS demyelinating diseases (including acute disseminated encephalomyelitis and neuromyelitic types of MS (NMO spectrum of disorders), either chronic or relapsing) (Weinshenker et al., 1999) . Clinical improvement was noted in 42.1% PLEX-treated patients compared with 5.9% in the sham group. A follow-up study by Keegan et al. (2005) suggested that patients with myelitis and Pattern II immunopathogenesis (according to Lucchinetti et al., 2000 , a predominantly antibodymediated disease) had the best response to PLEX. A recent retrospective analysis of 153 patients treated with PLEX for a steroid-refractory CNS demyelinating episode showed that 59% exhibited moderate to marked functional neurological improvement within 6 months following treatment (Magana et al., 2011) .

Logically, since NMO corresponds to the type-II histopathological phenotype of MS lesions, NMO patients are expected to have an optimal response to PLEX. Indeed two small open studies and a retrospective one in NMO patients during an acute attack of the disease showed an early and significant improvement following PLEX in most of the treated patients (Wang et al., 2011; Watanabe et al., 2007; Bonnan et al., 2009 ).

An American Academy of Neurology task committee, upon evaluating the neurological indications of PLEX, gave a level B recommendation for its use as second-line treatment of steroidresistant exacerbations in relapsing forms of MS and of NMO (Cortese et al., 2011) .

The First Generation: The 'Old Players'

The type-I IFNs (IFNa and IFNb) were first used in the 1970s on the grounds of their antiviral activity, which could possibly help in the elimination of the putative viral agents involved in MS pathogenesis. However, an initial trial with IFNg (type II) showed that the treatment actually promoted relapses of MS (Panitch et al., 1987) . IFNb, on the other hand (intrathecally or subcutaneously), induced beneficial effects in patients with MS (Jacobs et al., 1981; Panitch et al., 2004) .

IFNb was shown to inhibit T-cell activation, enhance suppressor cell activity, reduce IFNg production and MHC-II expression, increase IL-10 production, downregulate antigen presentation, induce a Th1 to Th2 shift, and reduce the permeability of the blood-brain barrier (Dhib-Jalbut and Marks, 2010).

In the first pivotal double-blind trial, recombinant IFNb-1b (Betaferon, Schering/Bayer), given subcutaneously every other day, was reported to reduce the relapse rate by 31% but without significantly affecting the disability status (The IFNB Multiple Sclerosis Study Group, 1993) . IFNb-treated patients had a significantly lower MRI T2 burden of disease and a 75-80% reduction in active scans (Paty and Li, 1993) . The treatment was generally well tolerated with the exception of 'flu-like' symptoms (fever, chills, myalgias, and fatigue) that occurred in the majority (76%) of patients, but tended to decrease after the first months of treatment. Injection-site irritation was also very common.

In a second study, recombinant glycosylated IFNb-1a (Avonex, Biogen), at a dose of 6 MIU intramuscularly once per week, induced a reduction in relapse rate by a similar (to Betaferon) rate. The treatment also resulted in a decrease in the number and volume of Gd-DTPA-enhancing lesions in the MRI and delayed the sustained progression of disability by about 40% (Jacobs et al., 2000) .

A third type of recombinant IFNb-1a (Rebif, Merk-Serono) (6 or 12 million IU subcutaneously every other day) (PRISMS Study Group, 1998) reduced the relapse risk by 27-33% and delayed the progression of disability and suppressed MRI activity (Li and Paty, 1999) . These beneficial effects of IFNb were shown to be long-lasting (Freedman, 2011; PRISMS-4, 2001; Ebers et al., 2010) .

Early treatment with IFNb in CIS patients showed to reduce the risk for conversion to CDMS over 2-3 years, by about 40% (Jacobs et al., 2000; Filippi et al., 2004; Kappos et al., 2006) . In a comparative study, Comi et al. (2012a) showed that the cumulative probability of McDonald definite MS was significantly lower in all patients treated with IFNb-1a, with a stronger beneficial effect of the higher-frequency regimen (Rebif).

A systematic review of the efficacy of IFNs in MS concluded that there is evidence only for RRMS, and this is mainly in terms of a reduction in relapse frequency during the first (and less in the second) year of treatment, with no convincing efficacy thereafter and no effect on the accumulation of disability (Rice et al., 2001) .

The data about the efficacy of IFNb in progressive MS are conflicting. One European study showed that Betaferon significantly increased (by 9-12 months) the time to confirmed disease progression and to becoming wheelchair bound compared with placebo in patients with SPMS (European Study Group, 1998) .

On the other hand, the North American trial on SPMS failed to show any beneficial effect of the same medication (Betaferon) on disease progression (Panitch et al., 2004) but only benefits in secondary outcome measures. The differences found between the outcomes of these two studies remain puzzling (Kappos et al., 2004) and might be related to the different populations of MS patients included in these two trials.

In another trial that tested IFNb-1a in SPMS, there was no significant effect on disability progression but suppressed superimposed relapses and MRI activity (PRISMS Study Group, 1998) . Finally, in a study with the third type of commercial IFN (Avonex) in 436 patients with SPMS , although no differences in EDSS were detected, there were significant beneficial effects on the Multiple Sclerosis Functional Composite (MSFC) scale and on the relapse-related parameters.

In PPMS, two randomized control trials failed to show beneficial effects of IFNb on disease progression (Rojas et al., 2010; Leary and Thompson, 2003; Montalban et al., 2009 ). Some differences favoring treatment were observed for the MSFC and in several secondary MRI parameters.

Three studies have compared the efficacy of the registered IFNs and reported greater efficacy of high-dose IFNb (Rebif or Betaferon) than the lower dose Avonex (IFNb-1a), but these trials were rather small and of short duration (Comi et al., 2012a; Panitch et al., 2002; Durelli et al., 2002) . On the other hand, another trial (Cadavid et al., 2009) showed no significant differences between Betaferon and Avonex in all outcomes (Koch-Henriksen et al., 2006) .

About 5-30% of IFNb-treated patients develop persistent neutralizing antibodies, usually in the first year of treatment and more commonly in those receiving IFNb-1b. Their presence is usually associated with a reduction in treatment effect (Malucchi et al., 2004; Francis et al., 2005; Hartung et al., 2011; Goodin et al., 2012; Pachner et al., 2009) .

Glatiramer acetate (GA; COP-1, Copaxone, Teva, Israel) is a synthetic co-polymer, composed of alanine; glutamine; lysine; and tyrosine, with some immunological similarities to the MBP molecule (and other myelin antigens), without itself being encephalitogenic. GA is presumed to block the MHC/TCR complex and to downregulate the antigen presentation to T cells (competitive inhibition) and/or induce regulatory cells (Racke et al., 2010) . In a pilot controlled study (Bornstein et al., 1987) , in 50 patients with RRMS, a great reduction in the number of relapses in the GA-treated group was reported. A later and larger pivotal, double-blind, trial (Johnson et al., 1995) showed that GA induced a 29% reduction in relapse rate, but without affecting the progression of disability at 2 years. MRI monitoring, performed in one of the centers, showed only marginal inhibition of the MRI activity. Adverse effects were usually mild, including mainly localized, injection-site reactions and a systemic reaction occurring within moments of GA administration (associated with chest pain, palpitations, or dyspnea) in 15% of the patients. In a separate randomized study treatment with GA led to a significant (10%) reduction in the total number of enhancing lesions compared with placebo (Comi et al., 2001) ; 57% of the patients treated for up to 22 years with GA maintained improved or unchanged EDSS scores and low annualized relapse rates Karussis et al., 2010a) . GA was also shown to reduce the risk of CIS patients to develop CDMS by 45% . A trial with GA in PPMS was terminated after an interim analysis that indicated no discernible treatment effect on primary outcome Sajja et al., 2008 ). An oral preparation of GA was shown ineffective evaluated in a later large trial including Filippi et al. (2006) .

In two comparative trials between GA and IFNb, no differences in any clinical or MRI parameters were observed between the treatment groups (Cadavid et al., 2009; O'Connor et al., 2009; Mikol et al., 2008) .

Data from an open pilot and a controlled study indicated that intravenous immunoglobulins (IVIG) had some efficacy in reducing the number of relapses and in the progression of disability in RRMS (Achiron et al., 1992; Fazekas et al., 1997a,b) . However, two other trials failed to show any efficacy of this treatment in patients with RRMS or progressive MS (Cook et al., 1992; Francis et al., 1997) . MRI monitoring in the latter trial did not reveal any effect of IVIG treatment in preventing the appearance of new lesions in the brain (Arnold et al., 1994) .

In SPMS, two studies (Hommes et al., 2004; Pohlau et al., 2007) failed to show any beneficial effects. In PPMS, a single study reported significantly less patients with EDSS progression in the IVIG-treated group than in the placebo group, with a nonsignificant trend to a delay in time to disease progression (Pohlau et al., 2007) .

MRI data reported in two RRMS studies (Lewanska et al., 2002; Fazekas et al., 2008) and in one on SPMS (Hommes et al., 2004) were conflicting and not convincing.

In an additional trial with clinical and MRI endpoints, significant differences were reported between the placebo and the IVIG-treatment groups (Sorensen et al., 1998) . However, this study suffers from considerable methodological difficulties, particularly with respect to blinding and allocation concealment.

Two additional trials (Noseworthy et al., 2000; Achiron et al., 1998) , of a rigorous methodological quality, were entirely negative across a wide range of clinical and paraclinical outcome measures.

Infusion-related side effects were reported in 4% of the participants treated with IVIG (Fazekas et al., 1997b; Hommes et al., 2004; Achiron et al., 1998) . One study reported six participants with deep venous thrombosis, four of whom also developed pulmonary embolism in the treatment group. IVIG was poorly tolerated in one trial (Fazekas et al., 2008) , with 11/21 (52%) experiencing severe cutaneous reactions. In the same study, there was one case with hepatitis C viral infection and one mortality from a pulmonary embolus (Fazekas et al., 1997a; Hommes et al., 2004; Pohlau et al., 2007; Achiron et al., 1998) .

Several immunosuppressive treatments have been tried in MS in the past decades, with variable efficacy.

Azathioprine, an antimetabolite with broad spectrum immunosuppressive effects and one of the main immunosuppressive cytotoxic substances available, is used extensively to control transplant rejection. By preventing the clonal expansion of lymphocytes it affects both cellular and humoral immunity. Azathioprine was tested in some pilot clinical trials (Achiron et al., 1998; British and Dutch Multiple Sclerosis Azathioprine Trial Group, 1988; Goodkin et al., 1991) . In the British and Dutch Multiple Sclerosis Trial (1988) it was shown to reduce the rate of progression at 3 years.

In total, azathioprine was tested in five controlled trials (Achiron et al., 1998; British and Dutch Multiple Sclerosis Azathioprine Trial Group, 1988; Goodkin et al., 1991) . Both relapsing and remitting MS patients and patients with progressive disease were included in these five trials. Almost half of the included patients suffered from progressive disease. Analysis of the cumulative data from 698 patients (from these five trials) showed that treatment with azathioprine caused a relative relapse risk reduction of 23% and 18% at 2 and 3 years, respectively (Casetta et al., 2009) . The proportion of patients who progressed during 2-3 years of treatment was 42% lower in the azathioprine group.

In one small study (Massacesi et al., 2005) , a reduction of 50% in gadolinium-enhancing lesions and T2 lesions was observed in patients treated with azathioprine.

The side effects of azathioprine include gastrointestinal discomfort or pain and a cutaneous rash (5% for each) and a 9% incidence of liver enzyme elevation. Macrocytic anemia occurred in 3% of the azathioprine-treated patients. There was a small but insignificant absolute increase of 3.4% in the risk for malignancies from a 3-year course of azathioprine and a slightly increased mortality rate in the azathioprine groups (Taylor et al., 2004) .

Cyclophosphamide is an alkylating drug that binds to DNA and interferes with mitosis and cell replication, suppressing thus both cellular and humoral immunity. Cyclophosphamide is commonly used as an antineoplastic drug and for the treatment of severe systemic autoimmune disorders.

Initial pilot open studies back in the early 1970s showed some positive indications of the efficacy of cyclophosphamide in MS, but these trials were open and uncontrolled (Hommes et al., 1975) .

Two large randomized trials reported conflicting results (Weiner et al., 1993a) . The beneficial effect observed in the first was seen mainly in young patients and the difference in stabilization rates was small and disappeared by 36 months. In the latter (The Canadian Cooperative Multiple Sclerosis Study Group, 1991) , there was no significant difference in the time to worsening in the EDSS.

Since the early 1990s there have been several trials and case reports with cyclophosphamide in patients with rapidly worsening or treatment-refractory MS, showing in general a moderate beneficial, clinical and neuroradiological effect on the activity of the disease (Hohol et al., 1999; Khan et al., 2001; Perini and Gallo, 2003; Zephir et al., 2004; de Bittencourt and Gomes-da-Silva, 2005; Gobbini et al., 1999) .

The combination of cyclophosphamide and IFNb-1a reduced clinical disease activity and gadolinium-enhancing MRI lesions in the brain Patti et al., 2004) .

Cyclophosphamide can cause several side effects, including alopecia, nausea, vomiting, hemorrhagic cystitis, leukopenia, myocarditis, infertility, and pulmonary interstitial fibrosis.

Mitoxantrone is an anthracenedione antineoplastic drug that intercalates with DNA and inhibits both DNA and RNA synthesis. Mitoxantrone inhibits B-cell function, including antibody secretion, abates helper and cytotoxic T-cell activity, and decreases the secretion of Th1 cytokines such as IFNg, TNFa, and IL-2 (Fox, 2004) .

A first placebo-controlled trial of mitoxantrone showed a significant reduction in the annual relapse rate and an increase in the proportion of patients who were relapse-free, but no differences in EDSS scores (Millefiorini et al., 1997) . In the subsequent phase III trial, in 194 patients with worsening RRMS or SPMS (Hartung et al., 2002) , the higher dose (12 mg m À2 q 3 months) of mitoxantrone was significantly more effective in the combined clinical outcome measurement, consisting of five clinical parameters (change in EDSS, change in ambulation index, number of treated relapses, time to first-treated relapse, and change in neurological status).

Addition of mitoxantrone to IFNb-treated patients, decreased the mean frequency and volume of gadoliniumenhancing lesions, by 90%, and the relapse rate by 64% (Jeffery et al., 2005) . Similar beneficial effects were observed also when mitoxantrone was added to GA (Ramtahal et al., 2006) .

Mitoxantrone is the only licensed cytotoxic medication for MS (for patients with SPMS, progressive relapsing or worsening RRMS), but its use is confined to cases with sufficiently aggressive MS to justify its toxic effects. Mitoxantrone causes cardiotoxicity (the cumulative allowed dose should not exceed 120 mg m À2 ) and acute leukemia (AML); the cumulative risk for both these adverse effects is 0.2%.

Methotrexate, a folic acid analog, is a potent immunosuppressant, whose mode of action is predominantly through inhibition of thymidine biosynthesis, although there are other anti-inflammatory effects, which do not rely upon this specific mechanism. By inhibiting purine and pyrimidine synthesis, methotrexate suppresses T-cell proliferation and promotion of adenosine-mediated inflammation. It is used in the treatment of autoimmune diseases and in transplantations.

In a placebo-controlled study, methotrexate, at a low dose, was reported to have a mild beneficial effect in a composite measure of EDSS, ambulation index, and two arm function tests, in progressive MS (Gray et al., 2006; Goodkin et al., 1995) . The effect of methotrexate on MRI activity was also marginal. Another trial with methotrexate (Currier et al., 1993) did not show any difference in EDSS progression in the progressive group. A more recent study (Sadiq et al., 2010) investigated the intrathecal administration of methotrexate in 121 progressive MS patients. No serious adverse effects were noted during the study period. In 89% of the 87 SPMS patients, EDSS scores were stable or improved.

In general, methotrexate toxicity is usually low if treatment is paralleled by folate substitution. However, long-term methotrexate administration may be associated with serious side effects, including hepatotoxicity and hepatic fibrosis.

Cyclosporin-A, is a cyclic fungal peptide, that inhibits calcineurin, similar in this aspect to tacrolimus. It is one of the most widely administered immunosuppressive drugs.

Cyclosporin A was studied in a 2-year, multicenter, doubleblind, clinical trial involving 547 progressive MS patients (The Multiple Sclerosis Study Group, 1990) . The mean increase in EDSS was 0.39 AE 1.07 for the cyclosporine-treated patients and 0.65 AE 1.08 in the placebo group. Cyclosporin A delayed the time to becoming wheelchair bound (relative risk: 0.765), but there was no statistical significance on 'time to sustained progression.'

The high rate of hypertension and nephrotoxicity induced by this treatment limit its use along with an increased risk for malignancies and skin cancers.

Cladribine is a synthetic purine nucleoside analog that preferentially accumulates in lymphocytes, disturbing DNA synthesis and repair mechanisms, and resulting in lymphocyte depletion and long-lasting lymphopenia. Because cladribine can penetrate the CNS, it interacts with cells in both the peripheral circulation and in the CNS. It is used as first-line treatment for hairy cell leukemia.

Older studies in a total of 262 patients have shown the efficacy of parenteral cladribine in RRMS and progressive MS, both in clinical and MRI parameters (Sipe et al., 1994; Beutler et al., 1996) . In a large and more recent phase III trial, a new preparation of oral cladribine (in two doses) and a new treatment scheme were tested in 1326 patients with RRMS (Giovannoni et al., 2010) . There was a significantly lower annualized relapse rate in both cladribine groups compared with the placebo group (by about 50%), and a lower risk of 3-month sustained progression of disability, paralleled by a reduction in the number of brain lesions in the MRI. Adverse events included lymphocytopenia and herpes zoster infections. Neoplasms arose in 1.4% of the treated patients.

Mycophenolate mofetil (MMF) belongs to the antimetabolite drug class and is a pro-drug of its active metabolite, mycophenolic acid. It inhibits T-and B-cell proliferation and, hence, immunoglobulin (Ig) production. MMF also suppresses dendritic cell maturation, decreasing their capacity of antigen presentation to T lymphocytes. Small trials in progressive MS suggest some efficacy, of MMF and its administration appeared to be well tolerated (Frohman et al., 2004; Ahrens et al., 2001) . Additionally, in an open-label trial, the combination of MMF with IFNb-1a exhibited superior efficacy, compared with IFNb-1a alone (Vermersch et al., 2007) . In a retrospective trial, MMF was shown to prevent relapses in 24 NMO patients (Jacob et al., 2009) . Adverse events include benign infectious diseases, insomnia and dizziness, nausea, and abdominal pains. There are still no controlled large studies with MMF in MS.

Tacrolimus/FK506 is a bacterial product that binds to the immunophilin FKBP1A. In this way, it prevents the cells from transitioning from the G0 to the G1 phase of the cell cycle. The drug, which is more potent than cyclosporin and has less pronounced side effects, is used primarily in transplantations. A pilot clinical trial (Lemster et al., 1994) with tacrolimus in chronic progressive MS showed that the overall degree of disability did not deteriorate significantly in the 19 patients studied over the 12 months of tacrolimus administration.

The rationale for combination immunotherapy (reviewed in Conway and Cohen, 2010) comes from the reported synergistic effects and increased efficacy of such combinations of immunomodulatory agents in other autoimmune diseases (Breedveld et al., 2006) . It is also justified by the acknowledged complexity of MS immunopathogenesis, which may necessitate the use of more than one drug to interfere with the various distinct immune elements involved at multiple levels of the immune axis, in order to maximize treatment efficacy (Figure 3a) . However, owing to the complex interactions and the delicate balance between the various immune cells and cytokine/ chemokine networks, unexpected or paradoxical effects may occur when different drugs affecting the immune system are combined. Small-size open studies have provided some positive indications supporting the principle of combination treatments such as methotrexate or azathioprine plus IFNb (Calabresi et al., 2002; Pulicken et al., 2005) . However, other larger controlled studies using IFN as basic therapy and methotrexate, steroids, or azathioprine as add-ons were negative (showing only some trends) (Havrdova et al., 2009; Cohen et al., 2009; Ravnborg et al., 2010) , with the exception of one (Sorensen et al., 2009) which showed a benefit of combination of IFN with steroids. The combination of natalizumab with IFNb showed some additional benefits in reduction of the relapse rate, but this trial was terminated because of two cases of progressive multifocal leukoencephalopathy (PML) in the natalizumab-Avonex combination group (Goodman et al., 2009a) . Addition of GA to natalizumab improved the neuroradilogical endpoints in this trial, but there was no additional benefit in terms of relapses and EDSS changes (Goodman et al., 200a) .

A randomized, double-blind, placebo-controlled trial of cyclophosphamide as an add-on therapy to IFNb and a singleblind-controlled trial revealed a benefit of addition of cyclophosphamide (with or without steroids) to IFNb (Patti et al., 2004; Smith et al., 2005) . Such treatment strategies entailing a rescue therapeutic scheme of strong immunosuppression (cyclophosphamide or mitoxantrone) followed by maintenance treatment with IFN or GA have been suggested and showed promising results Patti et al., 2004; Jeffery et al., 2005; Ramtahal et al., 2006; Edan et al., 2011) .

The combination of simvastatin, a cholesterol-lowering agent with putative immunomodulatory and neuroprotective properties, with IFNb-1a did not offer any additional beneficial effect (Sorensen et al., 2011) .

Monoclonal antibodies (mAb) are monospecific antibodies that are made by identical immune cells that are all clones of a unique parent cell, in contrast to polyclonal antibodies, which are made from several different immune cells. Monoclonal antibodies have monovalent affinity, in that they bind to the same antigenic epitope. Biologically synthesized mAbs can target precisely defined antigens like 'magic bullets' and represent a whole new category of timmunotherapeutic drugs.

Natalizumab is targeting the VLA4 surface molecule which is crucial for the transmigration of lymphocytes through the BBB to the CNS. Monthly infusions of this antibody showed strong efficacy against placebo, reducing the relapse rate at 1 year by 68% and the chance of acquiring fixed disability over 2 years by 42% . Moreover, natalizumab-treated patients were free of any disease activity (relapses, progression of disability, and new MRI activity) by around 30%. Although this efficacy appears higher than that observed in the IFN and GA pivotal studies, such cross comparison between different studies (of different design and MS patients populations) is not scientifically sound. US and European authorities licensed natalizumab for relapsing MS, but the drug was later withdrawn from the market when two cases of PML (progressive multifocal leucoencephalitis, an almost universally, lethal infection) were identified in a trial combining Avonex (IFNb-1a) with natalizumab (Rudick et al., 2006) . As a result, natalizumab is now licensed as monotherapy only for severe RRMS, or as secondline immunotherapy for MS. Since licensing, many (more than 300) additional cases of PML have been identified, almost exclusively among the patients treated for more than 2 years with natalizumab. Three parameters have been identified as being related to an increased risk of PML: (1) duration of treatment; (2) previous exposure to cytotoxic medications; and (3) the presence of anti-JC (John Cunningham) virus antibodies (which are found in half of the MS patients and indicate previous exposure to the virus) (Sorensen et al., 2012) . All reported cases of PML following natalizumab treatment were positive for the JC virus antibodies. Introduction of the test for these antibodies has helped in the selection of patients to be treated with natalizumab and those in whom the treatment should be discontinued due to a high risk (i.e., more than 1:1000 and in cases with all the above three risk factors, more than 1:100) of PML.

Alemtuzumab is a humanized monoclonal antibody targeting the CD52 antigen on T and B lymphocytes (Klotz et al., 2012) that produces rapid and sustained lymphocyte depletion. It is an approved therapy for B-cell chronic lymphocytic leukemia.

The first trial of alemtuzumab in RRMS was suspended after immune thrombocytopenic purpura developed in three patients, one of whom died. In this study, alemtuzumab treatment reduced the relapse rate compared with IFNb-1a by up to 74%, and the chance of accumulating disability by up to 71%, over 3 years. MRI outcomes were also significant, favoring alemtuzumab. Adverse events in the alemtuzumab group included autoimmunity (thyroid disorders and immune thrombocytopenic purpura (3%)) and infections.

Two consequent large phase III trials have been concluded in RRMS, showing a 49-55% reduction in relapse rate in the group treated with two annual cycles of alemtuzumab as compared with Rebif over 2 years and a 42% reduction of the risk of sustained accumulation of disability Coles et al., 2012) .

The side effects of alemtuzumab include a high incidence of autoimmune diseases (22%), especially autoimmune thrombocytopenia and thyroiditis (up to 33%) (Cossburn et al., 2011) .

Rituximab/ocrelizumab. The accumulating evidence on the involvement of B lymphocytes in the pathophysiology of MS paved the way for B-cell-directed therapies (Lassmann, 2007) . B-cell depletion affects antibody production, cytokine networks, and B-cell-mediated antigen presentation and activation of T cells and macrophages. Rituximab is a genetically engineered, chimeric murine/human IgG1 monoclonal antibody that targets the CD20 antigen, expressed only by pre-B and mature B cells.

Rituximab has shown significant efficacy in the suppression of several autoimmune disorders such as systemic lupus erythematosus (SLE) and rheumatoid arthritis.

Two pilot open studies, in 26 and 30 MS patients, tested the effect of two courses of rituximab 1000 mg, 6 months apart or with 375 mg m À2 weekly for 4 weeks. No serious adverse events were noted, except mild-to-moderate infusion-associated reactions. Fewer new gadolinium-enhancing or T2 lesions were seen in the rituximab-treated patients, associated with an apparent reduction in relapses (Bar-Or et al., 2008; Naismith et al., 2010) .

In a randomized, phase II, double-blind, trial, treatment with rituximab 1000 mg, given once every 6 months, led to a significant reduction of 91% in gadolinium-enhancing lesions seen on MRI, and in T2-weighted lesion volume, compared with placebo. Patients in the rituximab group had 50% lower annualized rate of relapses (Hauser et al., 2008) .

Rituximab treatment was also evaluated in 439 patients with PPMS (Hawker et al., 2009) . The patients received two 1000 mg intravenous rituximab or placebo infusions every 24 weeks, through 96 weeks (4 courses). The differences between the two groups in terms of time to confirmed disease progression were not significant, although rituximab patients had a significantly lower increase in T2 lesion volume. Subgroup analysis showed significant differences in time to confirmed disease progression in patients aged <51 years and those with gadolinium-enhancing lesions, compared with placebo. Adverse events were comparable between groups. However, serious infections occurred in 4.5% of the rituximab and <1.0% of the placebo patients.

Another, totally humanized, anti-CD20 monoclonal antibody, ocrelizumab, was also tested recently in 220 patients with RRMS in a large multicenter, randomized, double-blind, placebo-controlled study. At week 24, the number of gadolinium-enhancing lesions was 89% lower in the 600 mg ocrelizumab group than in the placebo group, and 96% lower in the 2000 mg group, with similarly pronounced effects in secondary relapse-related outcomes. Recently presented data from two large double-blind trials have shown significant efficacy of treatment with ocrelizumab both in relapsing MS and in PPMS (the only medication by now having shown a significant efficacy in PPMS).

Daclizumab targets the cell surface IL-2a receptor (CD25) which is expressed only by activated T-lymphocytes. IL-2 is an important immune system regulator necessary for clone expansion and survival of activated T-lymphocytes. Daclizumab acts by binding the IL-2a receptor's a-chain, preventing the IL-2-induced clonal expansion of activated lymphocytes and shortening their survival. It is used in the prophylaxis of acute organ rejection after bilateral kidney transplantation, with only a few side effects.

Few pilot studies with daclizumab provided indications of efficacy in reducing gadolinium-enhancing lesions in MS patients (van Oosten et al., 1996; Wynn et al., 2010; Bielekova et al., 2011) , accompanied by a significant expansion of natural killer (NK) cells in the peripheral blood and CSF.

In a first double-blind phase III trial against placebo, the annualized relapse rate was lower for patients given daclizumab HYP 150 mg subcutaneously every 4 weeks (54% reduction) or 300 mg (50% reduction) than for those given placebo. Slightly more patients in the daclizumab groups had serious adverse events excluding MS relapse (Gold et al., 2013) .

In a recently reported phase III trial, patients treated with daclizumab had a significantly lower (40%) annualized relapse rate than those treated with IFNb-1a. The number of new or newly enlarged hyperintense lesions on MRI was also lower in the daclizumab group (Kappos et al., 2015) .

Fingolimod (Gilenya, Novartis, Switzerland) modulates sphingosine-1-phosphate (S1P) receptors and has strong immunoregulatory properties since S1P1 receptor internalization appears to be a crucial step in the migration of lymphocytes. Neutralization of the S1P1 pathway inhibits the egress of T cells and B cells from the lymph nodes.

The results of two phase III studies in patients with RRMS (Kappos et al., 2010; Cohen et al., 2010) showed the efficacy of fingolimod over placebo, a clear superiority over IFNb-1a and an acceptable safety profile. ARR was reduced by 60% in the fingolimod 1.25 mg group compared to placebo and by 50% compared to IFNb1a. Fingolimod also significantly reduced the cumulative probability of the 3-month confirmed disability progression and showed superiority in all secondary MRI-related endpoints. The FDA approved fingolimod as firstline treatment for RRMS, whereas the European Medicines Agency (EMA) restricted its use as a second-line treatment or a first-line treatment in patients with active disease.

Fingolimod treatment causes significant lymphopenia, but its effects on circulating lymphocytes are reversible, with cell counts returning to normal within 4-6 weeks after cessation of treatment. Other adverse events related to fingolimod include bradycardia and atrioventricular conduction block during the start of fingolimod administration, macular edema, elevated liver enzyme levels, lymphocytopenia, and hypertension (all relative rare). Long-term safety data are warranted.

Teriflunomide is the active metabolite of leflunomide, which is approved for use in patients with rheumatoid arthritis. It reduces the activity of the mitochondrial enzyme dihydroorotate dehydrogenase, which is crucial in pyrimidine synthesis. T-lymphocyte proliferation largely depends on pyrimidine synthesis.

In a randomized, controlled, phase III trial in patients with active RRMS , both teriflunomide doses (7 or 14 mg) significantly lowered (by 30%) the ARR and by a similar degree the rate of disability worsening. The superiority of the drug versus placebo was confirmed for a range of MRI endpoints. Both teriflunomide doses were well tolerated, although diarrhea, nausea, and liver enzyme elevation were recorded. Teriflunomide has been suggested to have teratogenic, hepatotoxic, and myelosuppressive effects.

Results from a head-to-head trial (Vermersch et al., 2014) revealed no statistical superiority between the Rebif and teriflunomide arms on risk of treatment failure, the primary composite endpoint of the study. The drug with the trade name Aubagio was licensed by the FDA and EMA.

Dimethyl fumarate (BG12) is an oral formulation of dimethyl fumarate that induces activation of the nuclear factor E2-related pathway, which protects against oxidative stressrelated neuronal death and damage to myelin in the CNS. Several neuroprotective and anti-inflammatory mechanisms have been attributed to the drug, such as the expression of phase II detoxification enzymes in astroglial and microglial cells and a drug-induced shift toward a more antiinflammatory cytokine profile.

In a pilot study in patients with RRMS, an oral formulation of fumaric acid (Fumaderm, Biogen Idec), approved in Germany for the treatment of psoriasis, reduced the number of gadolinium-enhancing lesions in brain MRI scans (Schimrigk et al., 2006) . Subsequently, a phase IIb study in RRMS showed that BG-12 at 240 mg three times daily reduced the number of gadolinium-enhancing, new T2 and T1 lesions by 69%.

A large phase III trial showed that BG-12 at 240 mg twice or three times daily reduced by 53% the ARR and by 85-90%, the number of gadolinium-enhancing lesions and of new or enlarging T2 lesions compared with the placebo group. The cumulative probability of 3-month confirmed EDSS worsening was 38% lower. No new significant safety issues were reported (Gold et al., 2015) .

In another phase III parallel/comparative trial the annualized relapse rate was significantly lower in the BG-12 group and in the GA-treated arm than in the placebo group. Reductions in disability progression were not significant with either medication. BG-12 and GA had similar beneficial effects compared to placebo in terms of reducing the MRI activity. Adverse events associated with BG-12 include flushing and gastrointestinal events, such as diarrhea, nausea, and upper abdominal pain, as well as decreased lymphocyte counts and elevated liver enzyme levels. Lymphocyte counts tend to decrease with BG-12 and these chronically lymphopenic patients seem to have an increased risk for PML.

An additional, not yet approved, oral immunomodulatory drug is laquinimod (a derivative of linomide which effectively suppressed EAE and had a strong clinical effect in MS, which was shown in a phase III study (Comi et al., 2012b) to reduce by 23% the ARR, by 36% the EDSS worsening and by 33% the loss of brain volume over 2 years.

A second phase III study (Vollmer et al., 2014) failed to reveal a beneficial effect on relapse rate as compared to placebo but induced beneficial effects on EDSS progression and on brain volume loss.

T-cell Vaccination (TCV) was first introduced in 1981 in the EAE rat model, using activated and irradiated MBP-specific T-cell lines and clones (Ben-Nun et al., 1981) . The rationale was that vaccination with attenuated myelin-responsive T cells should induce an immune response against those cells which are probably the ones responsible for the inflammation and demyelination in MS (Zhang et al., 1993) .

Few small, phase II clinical trials with TCV at various stages of MS are already reported in the literature (Correale et al., 2000; Hermans et al., 1999 Hermans et al., , 2000 Medaer et al., 1995; Stinissen et al., 1996; Zhang, 2002; Vandenbark and Abulafia-Lapid, 2008; Achiron and Mandel, 2004; . These studies showed a consistent reduction in MBP-specific T cells following TCV and revealed indications of clinical efficacy.

A similar approach is to vaccinate with only the relevant anti-myelin antigen-responsive (Bourdette et al., 2005 ) T-cell receptor (Vandenbark et al., 1996) or using vaccines that contain altered myelin peptides (Kappos et al., 2000) .

Another unique approach for specific downregulation of the myelin-reactive lymphocytes, which are considered the main responder cells for the induction of demyelination, is utilizing oral tolerization techniques (Faria and Weiner, 2005) . An initial small-scale double-blind trial with early RRMS patients showed a trend to better clinical outcomes, and a reduction in MBP-reactive T cells in myelin-treated patients, without any adverse effects (Weiner et al., 1993a; Hohol et al., 1996) . However, the phase III trial did not confirm the efficacy of this therapy.

A slightly different approach, involving the administration of synthetic peptides derived from the sequence of MBP, by intrathecal and intravenous routes, was used in an attempt to tolerize patients Catz, 1995, 2000; Warren et al., 1997; Goodkin et al., 2000) .

Hematopoietic stem cell transplantation (HSCT) for MS (and autoimmune diseases in general) is based on the principle of radical suppression of the immune system to abrogate the inflammatory pathogenetic process in MS and subsequently reset the immune system from scratch. The autologous setting is usually used, where the immune system is reconstituted by the patient's own stem cells. The rationale for this type of therapeutic approach in MS derives from pivotal animal studies performed back in the early 1990s (Karussis et al., 1993a; . Open, uncontrolled clinical trials have shown impressive effects on the suppression of inflammation, induction of remission, and stabilization of MS (Fassas et al., 1997; Curro et al., 2015; Nash et al., 2015; Burt et al., 2015; Mancardi et al., 2015) .

Worldwide, more than 500 patients with MS have been treated with HSCT (reviewed by . The different conditioning protocols used in these studies complicate the uniform interpretation of the data. In general, an overall 85% 5-year survival rate and 43% progression-free survival have been recorded, with mean 100-day transplantationrelated mortality ranging from 1% to 5%.

Pivotal studies with neuronal stem cells have shown a significant beneficial clinical effect in mice with EAE (the animal model of MS) Ben-Hur et al., 2003; Pluchino et al., 2003) . Subsequently, embryonic and other types of adult stem cells, especially mesenchymal stem cells (MSCs), were tested in various models of EAE (Nicoletti et al., 2005; Kassis et al., 2008; Aharonowiz et al., 2008) . MSC injection, either intravenous or into the CSF, strongly suppressed the clinical and pathological signs of EAE and reversed disability. Most importantly, remyelination was evident in these MSC-treated animals, accompanied by impressive neuroprotection (Kassis et al., 2008) .

The additional scientific rationale for using MSC in EAE and MS derives from the reported strong immunomodulatory effects of these cells (Nauta and Fibbe, 2007; Uccelli et al., 2006 Uccelli et al., , 2007 . Phase I/II safety studies with MSC or bone marrow-derived cells have been performed in MS (Karussis et al., 2010b; Yamout et al., 2010) . Overall, MSCs given intravenously or intrathecally were well tolerated, with some preliminary evidence of efficacy Connick et al., 2012) .

Until 1993, no specific immunotherapy was registered for MS. Since the introduction of IFNb, huge steps have been made and increasingly more specific and efficacious ( Figure 4 ) modalities have been introduced and registered. However, along with the seemingly increasing efficacy of the newly introduced and more targeted immunotherapies, more safety issues have arisen. The cumulative experience obtained from the numerous clinical trials in MS with various types of immunotherapies allows one to draw the conclusion that inflammation, most probably initiated in the peripheral immune system, is crucial for the formation of new demyelinating lesions and, with time, appears to be the main cause for the resulting axonal damage and neuronal tissue atrophy. Immunological therapies, ideally applied as early as possible, might prevent progression of disability if given before the cascade of events that lead to irreversible tissue loss. The reported lower efficacy of most of the known immunotherapies in patients with progressive forms of MS might be explained by the possibility that inflammation is less pronounced or only compartmentalized in the CNS at these stages of the disease. More effective modalities that exert strong local immunomodulation in the CNS might be more beneficial for progressive MS. The additional goals of future MS therapy should include neuroprotective modalities and techniques that may enhance neuroregeneration and remyelination. High expectations of this direction are focused on stem cellrelated treatments, but these have to be substantiated in future controlled trials.

Finally, it is important to emphasise that MS is not a homogenous disease and distinct types of immune pathogenesis seem to be involved in different subgroups (Lucchinetti et al., 2000) . The use of neuroimaging and immunological biomarkers would help to tailor/personalize immunotherapy for each individual case.

Management of symptoms in MS (Poser and Brinar, 2002) such as the spasticity, pains (usually neuralgic), sphincter abnormalities, fatigue, memory decline, depression, and walking difficulties has received less attention compared with disease-modifying treatments. However, the effect of these symptoms on quality of life can be profound. The interest in pharmacological treatment of symptoms in MS has increased in recent years, and several large randomized controlled trials have been reported.

Controlled trials have proven the efficacy of modafinil (Brioschi et al., 2009; Moller et al., 2011) and amantadine (Ledinek et al., 2013) on fatigue and of fampridine on improving walking ability (and other motor functions) and reducing spasticity (Allart et al., 2015; Goodman et al., 2009b; Keune et al., 2015) . Medications used for control of pains (usually neuralgic pains, such as trigeminal neuralgia) include antiepileptic drugs (carbamazepine, lamotrigine, gabapentine, hydantoin, and so on) or antidepressive medications such as amitriptyline (Thompson et al., 2010; Zajicek and Apostu, 2011) . Baclophen, either orally or using an intrathecal pump, is the leading medication used to control spasticity, but also tizanidine; medical cannabis; or dantrolene have shown efficacy (United Kingdom Tizanidine Trial Group, 1994; Haselkorn et al., 2005; Lakhan and Rowland, 2009; Montalban, 2011; Rekand and Gronning, 2011; Schmidt et al., 1975; Stien et al., 1987; Vaney et al., 2004; Wade et al., 2006) .

Urinary problems can be managed by various medications depending on the type of dysfunction (i.e., urinary detrusor overactivity, urinary retention, or dyssynergia of the bladder) that include anticholinergics (such as ditropan) or a-blockers or a combination of them.

Pharmacological strategies are a core component of the treatment of MS symptoms, but it is imperative to remember that a multidisciplinary rehabilitation approach is needed for effective management.

Bolus" methylprednisolone versus ACTH in the treatment of multiple sclerosis

Prospective randomized double-blind comparison of moxalactam and tobramycin in treatment of urinary tract infections

Immunomodulation with linomide: possible novel therapy for multiple sclerosis

T-cell vaccination in multiple sclerosis

Open controlled therapeutic trial of intravenous immune globulin in relapsing-remitting multiple sclerosis

Intravenous immunoglobulin treatment in multiple sclerosis. Effect on relapses

Neuroprotective effect of transplanted human embryonic stem cell-derived neural precursors in an animal model of multiple sclerosis

Mycophenolate-mofetil in the treatment of refractory multiple sclerosis

Methylprednisolone in multiple sclerosis: a comparison of oral with intravenous therapy at equivalent high dose

Sustained-released fampridine in multiple sclerosis: effects on gait parameters, arm function, fatigue, and quality of life

T cells responsive to myelin basic protein in patients with multiple sclerosis

Epstein-Barr virus in pediatric multiple sclerosis

Multiple sclerosis among Orientals and Caucasians in Hawaii

Migration and risk of multiple sclerosis

Multiple sclerosis frequency in Israel's diverse populations

CXCL13 is a biomarker of inflammation in multiple sclerosis, neuromyelitis optica, and other neurological conditions

Benign multiple sclerosis: cognitive, psychological and social aspects in a clinical cohort

Viral infections trigger multiple sclerosis relapses: a prospective seroepidemiological study

The role of B cells and autoantibodies in multiple sclerosis

Use of proton magnetic resonance spectroscopy for monitoring disease progression in multiple sclerosis

Environmental risk factors for multiple sclerosis. Part I: the role of infection

Environmental factors in multiple sclerosis

Oligoclonal band number as a marker for prognosis in multiple sclerosis

Analyses of cerebrospinal fluid in the diagnosis and monitoring of multiple sclerosis

Clinical features and viral serologies in children with multiple sclerosis: a multinational observational study

Clustering of autoimmune diseases in families with a high-risk for multiple sclerosis: a descriptive study

Quantitative MRI changes in gadolinium-DTPA enhancement after high-dose intravenous methylprednisolone in multiple sclerosis

Comparison of MRI criteria at first presentation to predict conversion to clinically definite multiple sclerosis

Intravenous methylprednisolone for multiple sclerosis in relapse

Rituximab in relapsing-remitting multiple sclerosis: a 72-week, open-label, phase I trial

A randomized, controlled trial of corticosteroids in the treatment of acute optic neuritis. The Optic Neuritis Study Group

The effect of corticosteroids for acute optic neuritis on the subsequent development of multiple sclerosis. The Optic Neuritis Study Group

High-and low-risk profiles for the development of multiple sclerosis within 10 years after optic neuritis: experience of the optic neuritis treatment trial

The optic neuritis treatment trial

The optic neuritis treatment trial: three-year follow-up results

Transplanted multipotential neural precursor cells migrate into the inflamed white matter in response to experimental autoimmune encephalomyelitis

Vaccination against autoimmune encephalomyelitis with T-lymphocyte line cells reactive against myelin basic protein

Antimyelin antibodies as a predictor of clinically definite multiple sclerosis after a first demyelinating event

The treatment of chronic progressive multiple sclerosis with cladribine

Regulatory CD56(bright) natural killer cells mediate immunomodulatory effects of IL-2Ralpha-targeted therapy (daclizumab) in multiple sclerosis

Intrathecal effects of daclizumab treatment of multiple sclerosis

Multiple sclerosis: long-term remission after a high dose of cyclophosphamide

IFNbeta-1b may severely exacerbate Japanese opticspinal MS in neuromyelitis optica spectrum: Japanese optic-spinal MS: is it MS or neuromyelitis optica and does the answer dictate treatment

Plasma exchange in severe spinal attacks associated with neuromyelitis optica spectrum disorder

A pilot trial of Cop 1 in exacerbating-remitting multiple sclerosis

A highly immunogenic trivalent T cell receptor peptide vaccine for multiple sclerosis

Neurology in Clinical Practice

The PREMIER study: a multicenter, randomized, double-blind clinical trial of combination therapy with adalimumab plus methotrexate versus methotrexate alone or adalimumab alone in patients with early, aggressive rheumatoid arthritis who had not had previous methotrexate treatment

Serum anti-GAGA4 IgM antibodies differentiate relapsing remitting and secondary progressive multiple sclerosis from primary progressive multiple sclerosis and other neurological diseases

A longitudinal study of abnormalities on MRI and disability from multiple sclerosis

Investigation of the KIR4.1 potassium channel as a putative antigen in patients with multiple sclerosis: a comparative study

Increased anti-KIR4.1 antibodies in multiple sclerosis: could it be a marker of disease relapse?

Diagnostic imaging in acute disseminated encephalomyelitis

Effect of modafinil on subjective fatigue in multiple sclerosis and stroke patients

Double-masked trial of azathioprine in multiple sclerosis

Chlamydia pneumoniae and the risk for exacerbation in multiple sclerosis patients

Epstein-Barr virus and disease activity in multiple sclerosis

Varicella zoster virus is not a disease-relevant antigen in multiple sclerosis

Association of nonmyeloablative hematopoietic stem cell transplantation with neurological disability in patients with relapsing-remitting multiple sclerosis

New acute and chronic black holes in patients with multiple sclerosis randomised to interferon beta-1b or glatiramer acetate

Detection of cortical inflammatory lesions by double inversion recovery magnetic resonance imaging in patients with multiple sclerosis

Cortical lesions in multiple sclerosis

A 3-year magnetic resonance imaging study of cortical lesions in relapseonset multiple sclerosis

The predictive value of gray matter atrophy in clinically isolated syndromes

An open-label trial of combination therapy with interferon beta-1a and oral methotrexate in MS

MRI in acute disseminated encephalomyelitis

Subcortical deep gray matter pathology in patients with multiple sclerosis is associated with white matter lesion burden and atrophy but not with cortical atrophy: a diffusion tensor MRI study

Systematic review of cognitive dysfunction in pediatric and juvenile multiple sclerosis

Azathioprine for multiple sclerosis

Double-blind, placebo-controlled, randomized, crossover trial of high-dose methylprednisolone in patients with chronic progressive form of multiple sclerosis

Deep gray matter T2 hypointensity is present in patients with clinically isolated syndromes suggestive of multiple sclerosis

Shortlived plasma blasts are the main B cell effector subset during the course of multiple sclerosis

Cognitive impairment in multiple sclerosis

Benefit of interferon beta-1a on MSFC progression in secondary progressive MS

Results of the Avonex Combination Trial (ACT) in relapsing-remitting MS

Oral fingolimod or intramuscular interferon for relapsing multiple sclerosis

Alemtuzumab versus interferon beta 1a as first-line treatment for patients with relapsing-remitting multiple sclerosis: a randomised controlled phase 3 trial

Alemtuzumab vs. interferon beta-1a in early multiple sclerosis

Alemtuzumab for patients with relapsing multiple sclerosis after diseasemodifying therapy: a randomised controlled phase 3 trial

European/Canadian multicenter, double-blind, randomized, placebo-controlled study of the effects of glatiramer acetate on magnetic resonance imaging-measured disease activity and burden in patients with relapsing multiple sclerosis. European/Canadian Glatiramer Acetate Study Group

Effect of glatiramer acetate on conversion to clinically definite multiple sclerosis in patients with clinically isolated syndrome (PreCISe study): a randomised, doubleblind, placebo-controlled trial

Comparison of two dosing frequencies of subcutaneous interferon beta-1a in patients with a first clinical demyelinating event suggestive of multiple sclerosis (REFLEX): a phase 3 randomised controlled trial

Placebo-controlled trial of oral laquinimod for multiple sclerosis

Multiple sclerosis

Natural history of multiple sclerosis: a unifying concept

Rate of pregnancy-related relapse in multiple sclerosis. Pregnancy in Multiple Sclerosis Group

Autologous mesenchymal stem cells for the treatment of secondary progressive multiple sclerosis: an open-label phase 2a proof-of-concept study

Combination therapy in multiple sclerosis

Improvement of motor function in multiple sclerosis by use of protopam chloride

Prospective study of patients presenting with acute partial transverse myelopathy

T cell vaccination in secondary progressive multiple sclerosis

The risk of relapses in multiple sclerosis during systemic infections

Benign multiple sclerosis: a new definition of this entity is needed

Evidence-based guideline update: plasmapheresis in neurologic disorders: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Autoimmune disease after alemtuzumab treatment for multiple sclerosis in a multicenter cohort

Multiple sclerosis in pregnancy

Low dose oral methotrexate treatment of multiple sclerosis: a pilot study

Low intensity lympho-ablative regimen followed by autologous hematopoietic stem cell transplantation in severe forms of multiple sclerosis: a MRI-based clinical study

Cortical imaging in multiple sclerosis: recent findings and ʻgrand challengesʼ

Acute disseminated encephalomyelitis, multiphasic disseminated encephalomyelitis and multiple sclerosis in children

Application of the new McDonald criteria to patients with clinically isolated syndromes suggestive of multiple sclerosis

Early development of multiple sclerosis is associated with progressive grey matter atrophy in patients presenting with clinically isolated syndromes

Effects of influenza vaccination and influenza illness on exacerbations in multiple sclerosis

On the risk of multiple sclerosis according to age at immigration to South Africa

Clinical prognostic factors in multiple sclerosis: a natural history review

Cognitive impairment in multiple sclerosis: clinical, radiologic and pathologic insights

Interferon-beta mechanisms of action in multiple sclerosis

The month of birth effect in multiple sclerosis: systematic review, meta-analysis and effect of latitude

Every-other-day interferon beta-1b versus once-weekly interferon beta-1a for multiple sclerosis: results of a 2-year prospective randomised multicentre study (INCOMIN)

Genetics of multiple sclerosis

The geographic distribution of multiple sclerosis: a review

Analysis of clinical outcomes according to original treatment groups 16 years after the pivotal IFNB-1b trial

Genetic epidemiology of multiple sclerosis

Environmental factors and multiple sclerosis

Mitoxantrone prior to interferon beta-1b in aggressive relapsing multiple sclerosis: a 3-year randomised trial

Clinical relapses and disease activity on magnetic resonance imaging associated with viral upper respiratory tract infections in multiple sclerosis

Intraventricular transplantation of neural precursor cell spheres attenuates acute experimental allergic encephalomyelitis

Oral tolerance

Peripheral blood stem cell transplantation in the treatment of progressive multiple sclerosis: first results of a pilot study

Treatment effects of monthly intravenous immunoglobulin on patients with relapsing-remitting multiple sclerosis: further analyses of the Austrian Immunoglobulin in MS study

Randomised placebo-controlled trial of monthly intravenous immunoglobulin therapy in relapsing-remitting multiple sclerosis. Austrian Immunoglobulin in Multiple Sclerosis Study Group

Intravenous immunoglobulin in relapsing-remitting multiple sclerosis: a dose-finding trial

Cerebrospinal fluid CXCL13 in clinically isolated syndrome patients: association with oligoclonal IgM bands and prediction of multiple sclerosis diagnosis

Serum levels of CXCL13 are elevated in active multiple sclerosis

Serum and cerebrospinal fluid heavy neurofilaments and antibodies against them in early multiple sclerosis

Serum and cerebrospinal fluid light neurofilaments and antibodies against them in clinically isolated syndrome and multiple sclerosis

Magnetization transfer imaging to monitor the evolution of MS: a 1-year follow-up study

Interferon beta-1a for brain tissue loss in patients at presentation with syndromes suggestive of multiple sclerosis: a randomised, double-blind, placebocontrolled trial

Effects of oral glatiramer acetate on clinical and MRI-monitored disease activity in patients with relapsing multiple sclerosis: a multicentre, double-blind, randomised, placebo-controlled study

Intracortical lesions: relevance for new MRI diagnostic criteria for multiple sclerosis

Corticosteroids or ACTH for acute exacerbations in multiple sclerosis

Placebo-controlled phase 3 study of oral BG-12 or glatiramer in multiple sclerosis

Mechanism of action of mitoxantrone

Failure of intravenous immunoglobulin to arrest progression of multiple sclerosis: a clinical and MRI based study

Interferon beta-1a in MS: results following development of neutralizing antibodies in PRISMS

Recommended standard of cerebrospinal fluid analysis in the diagnosis of multiple sclerosis: a consensus statement

Anti-alpha-glucose-based glycan IgM antibodies predict relapse activity in multiple sclerosis after the first neurological event

Long-term follow-up of clinical trials of multiple sclerosis therapies

The utility of MRI in suspected MS: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Mycophenolate mofetil in multiple sclerosis

Multiple sclerosis-the plaque and its pathogenesis

Benign multiple sclerosis: physical and cognitive impairment follow distinct evolutions

EAE tolerance induction with Hsp70-peptide complexes depends on H60 and NKG2D activity

Role of the innate immune system in the pathogenesis of multiple sclerosis

Cortical lesions in multiple sclerosis: combined postmortem MR imaging and histopathology

Long-term follow-up of isolated optic neuritis: the risk of developing multiple sclerosis, its outcome, and the prognostic role of paraclinical tests

Infectious causes of multiple sclerosis

A placebo-controlled trial of oral cladribine for relapsing multiple sclerosis

Effect of open label pulse cyclophosphamide therapy on MRI measures of disease activity in five patients with refractory relapsing-remitting multiple sclerosis

Placebo-controlled phase 3 study of oral BG-12 for relapsing multiple sclerosis

Daclizumab high-yield process in relapsing-remitting multiple sclerosis (SELECT): a randomised, double-blind, placebo-controlled trial

Efficacy and safety of delayed-release dimethyl fumarate in patients newly diagnosed with relapsing-remitting multiple sclerosis (RRMS)

Neutralizing antibodies to interferon beta-1b multiple sclerosis: a clinicoradiographic paradox in the BEYOND trial

Seasonal variation of multiple sclerosis exacerbations in North Dakota

The efficacy of azathioprine in relapsing-remitting multiple sclerosis

Low-dose (7.5 mg) oral methotrexate reduces the rate of progression in chronic progressive multiple sclerosis

A phase I trial of solubilized DR2:MBP84-102 (AG284) in multiple sclerosis

GLANCE: results of a phase 2, randomized, double-blind, placebocontrolled study

Sustained-release oral fampridine in multiple sclerosis: a randomised, double-blind, controlled trial

A systematic review of oral methotrexate for multiple sclerosis

What is the true clinicopathologic spectrum of neuromyelitis optica?-Reply

Axonal damage in multiple sclerosis: a complex issue in a complex disease

Multiple sclerosis deep grey matter: the relation between demyelination, neurodegeneration, inflammation and iron

Neuroprotection by encephalomyelitis: rescue of mechanically injured neurons and neurotrophin production by CNS-infiltrating T and natural killer cells

Quantitative in vivo magnetic resonance imaging of multiple sclerosis at 7 Tesla with sensitivity to iron

Modelling the natural history of primary progressive multiple sclerosis

Mitoxantrone in progressive multiple sclerosis: a placebo-controlled, double-blind, randomised, multicentre trial

Interferon beta-1b-neutralizing antibodies 5 years after clinically isolated syndrome

Magnetic resonance imaging-based quantitative iron mapping at 7-tesla remains to be elusive in multiple sclerosis

Overview of spasticity management in multiple sclerosis. Evidence-based management strategies for spasticity treatment in multiple sclerosis

B-cell depletion with rituximab in relapsing-remitting multiple sclerosis

Randomized study of interferon beta-1a, low-dose azathioprine, and low-dose corticosteroids in multiple sclerosis

Principles of autoantibodies as diseasespecific markers

Rituximab in patients with primary progressive multiple sclerosis: results of a randomized double-blind placebo-controlled multicenter trial

B-cell-targeted treatment for multiple sclerosis: mechanism of action and clinical data

Toward the development of rational therapies in multiple sclerosis: what is on the horizon?

Cellular and humoral immune responses against autoreactive T cells in multiple sclerosis patients after T cell vaccination

Myelin reactive T cells after T cell vaccination in multiple sclerosis: cytokine profile and depletion by additional immunizations

Three-year open protocol continuation study of oral tolerization with myelin antigens in multiple sclerosis and design of a phase III pivotal trial

Treatment of progressive multiple sclerosis with pulse cyclophosphamide/ methylprednisolone: response to therapy is linked to the duration of progressive disease

Treatment of the chronic progressive form of multiple sclerosis with a combination of cyclophosphamide and prednisone

Intravenous immunoglobulin in secondary progressive multiple sclerosis: randomised placebo-controlled trial

Environmental factors associated with disease progression after the first demyelinating event: results from the multi-center SET study

The neuronal chemokine CX3CL1/fractalkine selectively recruits NK cells that modify experimental autoimmune encephalomyelitis within the central nervous system

Prognostic value of MR and magnetization transfer imaging findings in patients with clinically isolated syndromes suggestive of multiple sclerosis at presentation

Multiple sclerosis: a serial study using MRI in relapsing patients

Treatment of neuromyelitis optica with mycophenolate mofetil: retrospective analysis of 24 patients

Intrathecal interferon reduces exacerbations of multiple sclerosis

Impact of nuclear magnetic resonance imaging on the assessment of multiple sclerosis patients

Intramuscular interferon beta-1a therapy initiated during a first demyelinating event in multiple sclerosis

The effect of vitamin D-related interventions on multiple sclerosis relapses: a metaanalysis

A pilot trial of combination therapy with mitoxantrone and interferon beta-1b using monthly gadoliniumenhanced magnetic resonance imaging

Copolymer 1 reduces relapse rate and improves disability in relapsingremitting multiple sclerosis: results of a phase III multicenter, double-blind placebo-controlled trial. The Copolymer 1 Multiple Sclerosis Study Group

Multiple sclerosis: genetic versus environmental aetiology: epidemiology in Israel updated

Cerebral cortical lesions in multiple sclerosis detected by MR imaging at 8 Tesla

Magnetic resonance imaging in the evaluation of treatment in multiple sclerosis

Induction of a non-encephalitogenic type 2 T helper-cell autoimmune response in multiple sclerosis after administration of an altered peptide ligand in a placebocontrolled, randomized phase II trial. The Altered Peptide Ligand in Relapsing MS Study Group

Interferon beta-1b in secondary progressive MS: a combined analysis of the two trials

Treatment with interferon beta-1b delays conversion to clinically definite and McDonald MS in patients with clinically isolated syndromes

Effect of early versus delayed interferon beta-1b treatment on disability after a first clinical event suggestive of multiple sclerosis: a 3-year follow-up analysis of the BENEFIT study

Efficacy and safety of oral fumarate in patients with relapsing-remitting multiple sclerosis: a multicentre, randomised, double-blind, placebo-controlled phase IIb study

A placebo-controlled trial of oral fingolimod in relapsing multiple sclerosis

Ocrelizumab in relapsing-remitting multiple sclerosis: a phase 2, randomised, placebo-controlled, multicentre trial

Effect of BG-12 on contrast-enhanced lesions in patients with relapsingremitting multiple sclerosis: subgroup analyses from the phase 2b study

Daclizumab HYP versus interferon Beta-1a in relapsing multiple sclerosis

Evidence for the genetic role of human leukocyte antigens in low frequency DRB1*1501 multiple sclerosis patients in Israel

The frequency of multiple sclerosis in jewish and arab populations in greater jerusalem

The spectrum of post-vaccination inflammatory CNS demyelinating syndromes

Clinical experience with stem cells and other cell therapies in neurological diseases

Prevention of experimental autoimmune encephalomyelitis and induction of tolerance with acute immunosuppression followed by syngeneic bone marrow transplantation

Inhibition of acute, experimental autoimmune encephalomyelitis by the synthetic immunomodulator linomide

Treatment of chronic-relapsing experimental autoimmune encephalomyelitis with the synthetic immunomodulator linomide (quinoline-3-carboxamide)

Treatment of secondary progressive multiple sclerosis with the immunomodulator linomide: a double-blind, placebo-controlled pilot study with monthly magnetic resonance imaging evaluation

Long-term treatment of multiple sclerosis with glatiramer acetate: natural history of the subtypes of antiglatiramer acetate antibodies and their correlation with clinical efficacy

Safety and immunological effects of mesenchymal stem cell transplantation in patients with multiple sclerosis and amyotrophic lateral sclerosis

T cell vaccination benefits relapsing progressive multiple sclerosis patients: a randomized, double-blind clinical trial

Hematopoietic stem cell transplantation in multiple sclerosis

Immunotherapy of multiple sclerosis: the state of the art

The diagnosis of multiple sclerosis and the various related demyelinating syndromes: a critical review

Neuroprotection and immunomodulation with mesenchymal stem cells in chronic experimental autoimmune encephalomyelitis

A role for natural killer cells in the immunopathogenesis of multiple sclerosis

Clinical relapses of multiple sclerosis are associated with ʻnovelʼ valleys in natural killer cell functional activity

Human TH17 lymphocytes promote blood-brain barrier disruption and central nervous system inflammation

Relation between humoral pathological changes in multiple sclerosis and response to therapeutic plasma exchange

Quantitative magnetic resonance imaging in multiple sclerosis: the effect of high dose intravenous methylprednisolone

Dynamic walking features and improved walking performance in multiple sclerosis patients treated with fampridine (4-aminopyridine)

Cerebrospinal fluid CXCL13 in multiple sclerosis: a suggestive prognostic marker for the disease course

Effect of monthly intravenous cyclophosphamide in rapidly deteriorating multiple sclerosis patients resistant to conventional therapy

Cyclophosphamide and plasma exchange in multiple sclerosis

Incidence and prevalence of multiple sclerosis in Europe: a systematic review

Immune mechanisms of new therapeutic strategies in multiple sclerosis-A focus on alemtuzumab

Sequence analysis of human rhinovirus aspirated from the nasopharynx of patients with relapsing-remitting MS

The natural history of primary progressive multiple sclerosis

The natural history of early versus late disability accumulation in primary progressive MS

A randomized study of two interferon-beta treatments in relapsing-remitting multiple sclerosis

IL-17 and Th17 cells

Activity of multiple sclerosis during pregnancy and puerperium

The case for rhinoviruses in the pathogenesis of multiple sclerosis

Multiple sclerosis attacks are associated with picornavirus infections

Migraine as a risk factor for subclinical brain lesions

Chemokines in multiple sclerosis: CXCL12 and CXCL13 up-regulation is differentially linked to CNS immune cell recruitment

Antimyelin antibodies in clinically isolated syndromes correlate with inflammation in MRI and CSF

Lack of association between antimyelin antibodies and progression to multiple sclerosis

Acute hemorrhagic leukoencephalitis vs ADEM: FLAIR MRI and neuropathology findings

Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS)

Cortical demyelination in multiple sclerosis: a substrate for cognitive deficits?

Antibodies to Epstein-Barr virus and MRI disease activity in multiple sclerosis

HLA class II susceptibility to multiple sclerosis among Ashkenazi and non-Ashkenazi Jews

Whole plant cannabis extracts in the treatment of spasticity in multiple sclerosis: a systematic review

Cognition in multiple sclerosis

New concepts on progressive multiple sclerosis

Interferon beta-1a in primary progressive multiple sclerosis

Evaluating the effects of amantadin, modafinil and acetyl-L-carnitine on fatigue in multiple sclerosis-result of a pilot randomized, blind study

Evidence linking HHV-6 with multiple sclerosis: an update

Influence of FK 506 (tacrolimus) on circulating CD4 þ T cells expressing CD25 and CD45RA antigens in 19 patients with chronic progressive multiple sclerosis participating in an open label drug safety trial

No difference in efficacy of two different doses of intravenous immunoglobulins in MS: clinical and MRI assessment

Magnetic resonance imaging results of the PRISMS trial: a randomized, double-blind, placebo-controlled study of interferon-beta1a in relapsing-remitting multiple sclerosis. Prevention of relapses and disability by interferon-beta1a subcutaneously in multiple sclerosis

Quantitative PCR for Epstein-Barr virus DNA and RNA in multiple sclerosis

Oligoclonal bands in multiple sclerosis cerebrospinal fluid: an update on methodology and clinical usefulness

New multiple sclerosis phenotypic classification

Heterogeneity of multiple sclerosis lesions: implications for the pathogenesis of demyelination

Clinical and radiographic spectrum of pathologically confirmed tumefactive multiple sclerosis

Inflammatory cortical demyelination in early multiple sclerosis

Acute haemorrhagic encephalomyelitis (AHEM): MRI findings

Beneficial plasma exchange response in central nervous system inflammatory demyelination

Meningeal B-cell follicles in secondary progressive multiple sclerosis associate with early onset of disease and severe cortical pathology

In vivo imaging of cortical pathology in multiple sclerosis using ultrahigh field MRI

Neutralizing antibodies reduce the efficacy of betaIFN during treatment of multiple sclerosis

Autologous hematopoietic stem cell transplantation in multiple sclerosis: a phase II trial

A short-term randomized MRI study of high-dose oral vs intravenous methylprednisolone in MS

Soluble adhesion molecules in acute disseminated encephalomyelitis

Clinically isolated syndromes: a new oligoclonal band test accurately predicts conversion to MS

Efficacy of azathioprine on multiple sclerosis new brain lesions evaluated using magnetic resonance imaging

The lectin-like NK cell receptor Ly-49A recognizes a carbohydrateindependent epitope on its MHC class I ligand

The innate immune system in demyelinating disease

Recommended diagnostic criteria for multiple sclerosis: guidelines from the International Panel on the diagnosis of multiple sclerosis

Analysis of neutralizing antibodies to therapeutic interferon-beta in multiple sclerosis patients: a comparison of three methods in a large Australasian cohort

Diagnosis of neuromyelitis spectrum disorders: comparative sensitivities and specificities of immunohistochemical and immunoprecipitation assays

Depletion of myelinbasic-protein autoreactive T cells by T-cell vaccination: pilot trial in multiple sclerosis

Acute disseminated encephalomyelitis: an acute hit against the brain

Increased risk of multiple sclerosis relapse after in vitro fertilisation

Acute disseminated encephalomyelitis cohort study: prognostic factors for relapse

Comparison of subcutaneous interferon beta-1a with glatiramer acetate in patients with relapsing multiple sclerosis (the REbif vs Glatiramer Acetate in Relapsing MS Disease [REGARD] study): a multicentre, randomised, parallel, openlabel trial

Randomized placebo-controlled trial of mitoxantrone in relapsing-remitting multiple sclerosis: 24-month clinical and MRI outcome

Primary-progressive multiple sclerosis

The early risk of multiple sclerosis after optic neuritis

Magnetic resonance imaging in monitoring the treatment of multiple sclerosis: concerted action guidelines

High dose steroids in acute relapses of multiple sclerosis: MRI evidence for a possible mechanism of therapeutic effect

The role of magnetic resonance techniques in understanding and managing multiple sclerosis

Clinically isolated syndromes suggestive of multiple sclerosis, part I: natural history, pathogenesis, diagnosis, and prognosis

Clinically isolated syndromes suggestive of multiple sclerosis, part 2: non-conventional MRI, recovery processes, and management

Long-term (up to 22 years), open-label, compassionate-use study of glatiramer acetate in relapsingremitting multiple sclerosis

Multiple sclerosis: geoepidemiology, genetics and the environment

Infratentorial lesions predict long-term disability in patients with initial findings suggestive of multiple sclerosis

HAGIL (Hamburg Vigil Study): a randomized placebo-controlled double-blind study with modafinil for treatment of fatigue in patients with multiple sclerosis

A single-center, randomized, double-blind, placebo-controlled study of interferon beta-1b on primary progressive and transitional multiple sclerosis

MRI criteria for MS in patients with clinically isolated syndromes

New insights in the pathophysiology and treatment of multiple sclerosis spasticity and related symptoms

Role of natural killer cells in the pathogenesis and progression of multiple sclerosis

Incidental findings on brain magnetic resonance imaging: systematic review and meta-analysis

The significance of brain magnetic resonance imaging abnormalities at presentation with clinically isolated syndromes suggestive of multiple sclerosis. A 5-year follow-up study

Staphylococcus aureus harbouring Enterotoxin A as a possible risk factor for multiple sclerosis exacerbations

Acute disseminated encephalomyelitis in children

Rituximab add-on therapy for breakthrough relapsing multiple sclerosis: a 52-week phase II trial

High-dose immunosuppressive therapy and autologous hematopoietic cell transplantation for relapsing-remitting multiple sclerosis (HALT-MS): a 3-year interim report

Immunomodulatory properties of mesenchymal stromal cells

Deep gray matter involvement on brain MRI scans is associated with clinical progression in multiple sclerosis

Improved identification of intracortical lesions in multiple sclerosis with phase-sensitive inversion recovery in combination with fast double inversion recovery MR imaging

Possible increasing risk of multiple sclerosis in Catania

Cyclophosphamide and plasma exchange in multiple sclerosis

IV immunoglobulin does not reverse established weakness in MS

250 microg or 500 microg interferon beta-1b versus 20 mg glatiramer acetate in relapsing-remitting multiple sclerosis: a prospective, randomised, multicentre study

Randomized trial of oral teriflunomide for relapsing multiple sclerosis

Incidental MRI anomalies suggestive of multiple sclerosis: the radiologically isolated syndrome

Increased MRI activity and immune activation in two multiple sclerosis patients treated with the monoclonal anti-tumor necrosis factor antibody cA2

Brief presence of varicella-zoster vral DNA in mononuclear cells during relapses of multiple sclerosis

The prognostic value of brain MRI in clinically isolated syndromes of the CNS. A 10-year follow-up

The role of NMR imaging in the assessment of multiple sclerosis and isolated neurological lesions. A quantitative study

The B cell response in multiple sclerosis

Effect of neutralizing antibodies on biomarker responses to interferon beta: the INSIGHT study

Exacerbations of multiple sclerosis in patients treated with gamma interferon

Randomized, comparative study of interferon beta-1a treatment regimens in MS: the EVIDENCE Trial

Interferon beta-1b in secondary progressive MS: results from a 3-year controlled study

A prospective study on the predictive value of CSF oligoclonal bands and MRI in acute isolated neurological syndromes for subsequent progression to multiple sclerosis

Stabilization of rapidly worsening multiple sclerosis for 36 months in patients treated with interferon beta plus cyclophosphamide followed by interferon beta

Interferon beta-1b is effective in relapsing-remitting multiple sclerosis. II. MRI analysis results of a multicenter, randomized, doubleblind, placebo-controlled trial. UBC MS/MRI Study Group and the IFNB Multiple Sclerosis Study Group

Antimyelin antibodies with no progression to multiple sclerosis

Do multimodal evoked potentials add information to MRI in clinically isolated syndromes?

Cyclophosphamide is effective in stabilizing rapidly deteriorating secondary progressive multiple sclerosis

Placebo-controlled multicentre randomised trial of interferon beta-1b in treatment of secondary progressive multiple sclerosis. European Study Group on interferon beta-1b in secondary progressive MS

Injection of adult neurospheres induces recovery in a chronic model of multiple sclerosis

High seroprevalence of Epstein-Barr virus in children with multiple sclerosis

Intravenous immunoglobulin in primary and secondary chronic progressive multiple sclerosis: a randomized placebo controlled multicentre study

Diagnostic criteria for multiple sclerosis: 2005 revisions to the "McDonald Criteria

A randomized, placebo-controlled trial of natalizumab for relapsing multiple sclerosis

Subgroups of the BENEFIT study: risk of developing MS and treatment effect of interferon beta-1b

Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria

Meningeal and cortical grey matter pathology in multiple sclerosis

Pathology of multiple sclerosis: where do we stand?

The symptomatic treatment of multiple sclerosis

The nature of multiple sclerosis

Diagnostic criteria for multiple sclerosis: an historical review

New diagnostic criteria for multiple sclerosis: guidelines for research protocols

Schilder's myelinoclastic diffuse sclerosis

The multiple sclerosis trait and the development of multiple sclerosis: genetic vulnerability and environmental effect

MRI in multiple sclerosis during the menstrual cycle: relationship with sex hormone patterns

Randomised double-blind placebo-controlled study of interferon beta-1a in relapsing/remitting multiple sclerosis

PRISMS-4: long-term efficacy of interferon-beta-1a in relapsing MS

Optimization of the safety and efficacy of interferon beta 1b and azathioprine combination therapy in multiple sclerosis

Epitope spreading as an early pathogenic event in pediatric multiple sclerosis

The mechanism of action of glatiramer acetate treatment in multiple sclerosis

Clustering of autoimmune disease in families at high risk for multiple sclerosis?

Sequential maintenance treatment with glatiramer acetate after mitoxantrone is safe and can limit exposure to immunosuppression in very active, relapsing remitting multiple sclerosis

Methylprednisolone in combination with interferon beta-1a for relapsing-remitting multiple sclerosis (MECOMBIN study): a multicentre, doubleblind, randomised, placebo-controlled, parallel-group trial

Treatment of spasticity related to multiple sclerosis with intrathecal baclofen: a long-term follow-up

Interferon in relapsing-remitting multiple sclerosis

Tumefactive demyelination and glioblastoma: a rare collision lesion

Interferon Beta for primary progressive multiple sclerosis

Systemic inflammation in progressive multiple sclerosis involves follicular T-helper, Th17-and activated B-cells and correlates with progression

The prevalence of multiple sclerosis in the world: an update

Cooperative study in the evaluation of therapy in multiple sclerosis. ACTH vs. placebo-final report

Acute hemorrhagic leukoencephalitis: recovery and reversal of magnetic resonance imaging findings in a child

Clinical, MRI, CSF and electrophysiological findings in different stages of multiple sclerosis

Cognitive impairment and structural brain damage in benign multiple sclerosis

Evidence-based guidelines: MAGNIMS consensus guidelines on the use of MRI in multiple sclerosis-clinical implementation in the diagnostic process

MRI lesions: a surrogate for relapses in multiple sclerosis?

Current approaches to the identification and management of breakthrough disease in patients with multiple sclerosis

Management of multiple sclerosis

The multiple sclerosis functional composite: a new clinical outcome measure for multiple sclerosis trials

Natalizumab plus interferon beta-1a for relapsing multiple sclerosis

Association of deep gray matter damage with cortical and spinal cord degeneration in primary progressive multiple sclerosis

Pregnancy is associated with a lower risk of onset and a better prognosis in multiple sclerosis

Intrathecal methotrexate treatment in multiple sclerosis

Season of birth in multiple sclerosis

Pregnancy and multiple sclerosis. A prospective study

Genetics of multiple sclerosis in British Columbia and throughout Canada

Longitudinal magnetic resonance spectroscopic imaging of primary progressive multiple sclerosis patients treated with glatiramer acetate: multicenter study

Vitamin D as a protective factor in multiple sclerosis

Vitamin D and multiple sclerosis: where do we go from here?

Expansion of CD56 Bright natural killer cells in the peripheral blood of multiple sclerosis patients treated with interferon-beta

Conversion to multiple sclerosis after a clinically isolated syndrome of the brainstem: cranial magnetic resonance imaging, cerebrospinal fluid and neurophysiological findings

The genetic analysis of multiple sclerosis

The psychosocial and cognitive impact of longstanding 'benign' multiple sclerosis

Oral fumaric acid esters for the treatment of active multiple sclerosis: an openlabel, baseline-controlled pilot study

Treatment of spasticity in multiple sclerosis: comparison of dantrolene sodium and diazepam

Problems of experimental trials of therapy in multiple sclerosis: report by the panel on the evaluation of experimental trials of therapy in multiple sclerosis

Serum anti-Glc(alpha1,4)Glc(alpha) antibodies as a biomarker for relapsing-remitting multiple sclerosis

Acute partial transverse myelitis with normal cerebral magnetic resonance imaging: transition rate to clinically definite multiple sclerosis

Double-blind, randomized, placebo-controlled study of oral, high-dose methylprednisolone in attacks of MS

Detection of ectopic B-cell follicles with germinal centers in the meninges of patients with secondary progressive multiple sclerosis

In vivo relationship of interleukin-2 and soluble IL-2 receptor to blood-brain barrier impairment in patients with active multiple sclerosis

Increased levels of circulating ICAM-1 in serum and cerebrospinal fluid of patients with active multiple sclerosis. Correlation with TNF-alpha and blood-brain barrier damage

Infection and immunization in multiple sclerosis

Clinical viral infections and multiple sclerosis

Multiple sclerosis in diverse populations: characteristics in distinct Arab ethnicities in Israel

Standardized MR imaging protocol for multiple sclerosis: Consortium of MS Centers consensus guidelines

EBV & HHV6 reactivation is infrequent and not associated with MS clinical course

Cladribine in treatment of chronic progressive multiple sclerosis

A randomized blinded trial of combination therapy with cyclophosphamide in patients-with active multiple sclerosis on interferon beta

The relevance of vitamin D receptor gene polymorphisms for vitamin D research in multiple sclerosis

Intravenous immunoglobulin G reduces MRI activity in relapsing multiple sclerosis

NORdic trial of oral methylprednisolone as add-on therapy to interferon beta-1a for treatment of relapsing-remitting multiple sclerosis (NORMIMS study): a randomised, placebo-controlled trial

Simvastatin as add-on therapy to interferon beta-1a for relapsing-remitting multiple sclerosis (SIMCOMBIN study): a placebo-controlled randomised phase 4 trial

Risk stratification for progressive multifocal leukoencephalopathy in patients treated with natalizumab

Varicella-zoster virus at relapses of multiple sclerosis

Varicella-zoster virus in cerebrospinal fluid at relapses of multiple sclerosis

Potassium channel KIR4.1 as an immune target in multiple sclerosis

Infection as an environmental trigger of multiple sclerosis disease exacerbation

Multiple sclerosis: a two-stage disease

The treatment of spasticity in multiple sclerosis: a double-blind clinical trial of a new anti-spastic drug tizanidine compared with baclofen

Vaccination with autoreactive T cell clones in multiple sclerosis: overview of immunological and clinical data

Magnetic resonance images on Marburg variant

MRI criteria for multiple sclerosis in patients presenting with clinically isolated syndromes: a multicentre retrospective study

Natural killer type 2 bias in remission of multiple sclerosis

What is acute disseminated encephalomyelitis (ADEM)?

The risk of cancer from azathioprine as a treatment for multiple sclerosis

Th17 cells in human disease

Neurofilaments as biomarkers in multiple sclerosis

Combination of CSF N-acetylaspartate and neurofilaments in multiple sclerosis

The Canadian cooperative trial of cyclophosphamide and plasma exchange in progressive multiple sclerosis

Interferon beta-1b is effective in relapsing-remitting multiple sclerosis. I. Clinical results of a multicenter, randomized, double-blind, placebo-controlled trial

Efficacy and toxicity of cyclosporine in chronic progressive multiple sclerosis: a randomized, double-blinded, placebocontrolled clinical trial

Relative efficacy of intravenous methylprednisolone and ACTH in the treatment of acute relapse in MS

Pharmacological management of symptoms in multiple sclerosis: current approaches and future directions

Isolated demyelinating syndromes: comparison of CSF oligoclonal bands and different MR imaging criteria to predict conversion to CDMS

New diagnostic criteria for multiple sclerosis: application in first demyelinating episode

Do oligoclonal bands add information to MRI in first attacks of multiple sclerosis

Anti-myelin antibodies predict the clinical outcome after a first episode suggestive of MS

Multiple sclerosis: an immune or neurodegenerative disorder?

Axonal transection in the lesions of multiple sclerosis

Natural history of secondaryprogressive multiple sclerosis

Increased levels of intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor receptor in the cerebrospinal fluid of patients with multiple sclerosis

Adhesion of cerebral endothelial cells to lymphocytes from patients with multiple sclerosis

Cytotoxicity of T cells for cerebral endothelium in multiple sclerosis

Immunoregulatory function of mesenchymal stem cells

Mesenchymal stem cells: a new strategy for immunosuppression?

A double-blind, placebo-controlled trial of tizanidine in the treatment of spasticity caused by multiple sclerosis

Autologous T-cell vaccination for multiple sclerosis: a perspective on progress

Treatment of multiple sclerosis with T-cell receptor peptides: results of a double-blind pilot trial

Epitope spreading

Epitope spreading in immune-mediated diseases: implications for immunotherapy

Efficacy, safety and tolerability of an orally administered cannabis extract in the treatment of spasticity in patients with multiple sclerosis: a randomized, double-blind, placebo-controlled, crossover study

Memory CD4 þ CD127 high T cells from patients with multiple sclerosis produce IL-17 in response to myelin antigens

Combination of IFN beta-1a (Avonex) and mycophenolate mofetil (Cellcept) in multiple sclerosis

Teriflunomide versus subcutaneous interferon beta-1a in patients with relapsing multiple sclerosis: a randomised

Incidental findings on brain MRI in the general population

A randomized placebo-controlled phase III trial of oral laquinimod for multiple sclerosis

Natural history of multiple sclerosis: risk factors and prognostic indicators

Long-term use of a cannabis-based medicine in the treatment of spasticity and other symptoms in multiple sclerosis

The rescue effect of plasma exchange for neuromyelitis optica

Administration of myelin basic protein synthetic peptides to multiple sclerosis patients

Kinetic profiles of cerebrospinal fluid anti-MBP in response to intravenous MBP synthetic peptide DENP(85)VVHFFKNIVTP(96)RT in multiple sclerosis patients

Tolerance induction to myelin basic protein by intravenous synthetic peptides containing epitope P85 VVHFFKNIVTP96 in chronic progressive multiple sclerosis

Expression of immunologically relevant endothelial cell activation antigens on isolated central nervous system microvessels from patients with multiple sclerosis

Therapeutic efficacy of plasma exchange in NMO-IgG-positive patients with neuromyelitis optica

High field MR imaging and 1H-MR spectroscopy in clinically isolated syndromes suggestive of multiple sclerosis: correlation between metabolic alterations and diagnostic MR imaging criteria

Does high field MRI allow an earlier diagnosis of multiple sclerosis?

MRI in the diagnosis and monitoring of multiple sclerosis: an update

Double-blind study of true vs. sham plasma exchange in patients treated with immunosuppression for acute attacks of multiple sclerosis

Intermittent cyclophosphamide pulse therapy in progressive multiple sclerosis: final report of the Northeast Cooperative Multiple Sclerosis Treatment Group

Double-blind pilot trial of oral tolerization with myelin antigens in multiple sclerosis

A randomized trial of plasma exchange in acute central nervous system inflammatory demyelinating disease

Timing of birth and risk of multiple sclerosis: population based study

Acute disseminated encephalomyelitis, transverse myelitis, and neuromyelitis optica

Revised diagnostic criteria for neuromyelitis optica

The spectrum of neuromyelitis optica

Neuromyelitis optica spectrum disorders

Glatiramer acetate in primary progressive multiple sclerosis: results of a multinational, multicenter, double-blind, placebo-controlled trial

Acute necrotizing encephalopathy of childhood: correlation of MR findings and clinical outcome

Molecular mimicry in T cell-mediated autoimmunity: viral peptides activate human T cell clones specific for myelin basic protein

Daclizumab in active relapsing multiple sclerosis (CHOICE study): a phase 2, randomised, double-blind, placebo-controlled, add-on trial with interferon beta

Mechanism of natural killer (NK) cell regulatory role in experimental autoimmune encephalomyelitis

Bone marrow mesenchymal stem cell transplantation in patients with multiple sclerosis: a pilot study

Prevention of experimental autoimmune encephalomyelitis by antibodies against alpha 4 beta 1 integrin

Role of cannabinoids in multiple sclerosis

Treatment of progressive forms of multiple sclerosis by cyclophosphamide: a cohort study of 490 patients

Immune-mediated CNS diseases: a review on nosological classification and clinical features

MHC-restricted depletion of human myelin basic protein-reactive T cells by T cell vaccination

Increased frequency of interleukin 2-responsive T cells specific for myelin basic protein and proteolipid protein in peripheral blood and cerebrospinal fluid of patients with multiple sclerosis

Regulation of experimental autoimmune encephalomyelitis by natural killer (NK) cells

T-cell vaccination for autoimmune diseases: immunologic lessons and clinical experience in multiple sclerosis

The contribution of cerebrospinal fluid oligoclonal bands to the early diagnosis of multiple sclerosis

Neuroimaging in multiple sclerosis

Effects of IV methylprednisolone on brain atrophy in relapsingremitting MS

B lymphocytes-chief players and therapeutic targets in autoimmune diseases

The author would like to thank Dr Panayiota Petrou for her great help and contribution in the writing and reviewing of this manuscript.See also: Autoimmune Diseases; Poliomyelitis; Poliomyelitis, Historical.