key: cord-0857755-cfx6rkvo
authors: Theodorou, Daphne J; Theodorou, Stavroula J; Tsaggou, Vasiliki; Tsifetaki, Niki
title: Anosmia caused by ischemic olfactory infarction: false alert for COVID-19 infection
date: 2020-10-20
journal: QJM
DOI: 10.1093/qjmed/hcaa294
sha: bb1decf0b50c9cd84ff13b1effe08c8694f3d0da
doc_id: 857755
cord_uid: cfx6rkvo

nan

1 Anosmia caused by ischemic olfactory infarction: false alert for COVID-19 infection

Anosmia is increasingly recognized as a complication of SARS-CoV-2 infection, or a clinical symptom that can merely mimic virus-induced olfactory dysfunction. MRI can play a major role in the detection of underlying abnormalities of the olfactory system, excluding the possibility of COVID-19-induced anosmia. This case indicates that the cause of anosmia needs to be carefully investigated, particularly in those patients who are at an increased risk for CoV-2 infection to eliminate overcall diagnosis of the disease.

A 68-year-old female patient, living in a nursing home presented to the emergency room of our hospital with sudden onset of anosmia (loss of smell), and a 3-day history of paroxysmal dry cough, headache, and malaise. Comorbidities included a history of type-2 diabetes and chronic gastritis, while no previous neurologic history or head trauma was recorded. Her body temperature was 100.04 °F (37.8°C) and blood pressure was normal. Mild dyspnoea, with no nasal congestion was present at the time of admission. Neurologic examination showed normal consciousness, with normal vision and auditory functions, and unaffected taste sense. The patient complained of total anosmia that was confirmed by failure to identify odours presented on both sides of her nose, while keeping her eyes closed. Laboratory studies showed iron-deficiency anaemia, and normal white blood cell, neutrophil and lymphocyte count. C-reactive protein was elevated. In light of the ongoing COVID-19 pandemic, intimidating clinical presentation of the patient with complete loss of smell was alarming for coronavirus infection insulting CN-I (olfactory nerve). As such, sputum analysis using real-time reverse transcriptase fluorescence polymerase chain reaction was performed that yielded negative results for infection. Chest radiography and CT scans obtained at admission showed no significant findings.

Brain CT revealed bilateral, hypodense lesions involving the straight gyri at the inferior frontal lobe. Magnetic resonance imaging (MRI) was then scheduled that depicted abnormal high-signal-intensity lesions adjacent to the olfactory sulci on the T2-weighted and FLAIR MR images, consistent with ischemic infarcts (Fig. 1) .

Interestingly, the site of infarcts correlated closely with the known anatomic distribution of the olfactory tract in the rhinencephalon (smell brain), a finding offering a plausible explanation for anosmia [9, 10]. The patient was informed accordingly and was subsequently discharged, with dietary/nutrition modification guidelines. that anosmia may relate to CoV-2-mediated neuronal damage to the olfactory apparatus [5] . In that same vein Galougahi et al were first to address the need for dedicated MRI examination of the olfactory bulb to investigate anosmia, in a single patient with COVID-19 infection [6] . The MRI findings in our case with high clinical suspicion for coronavirus infection efficaciously ruled out COVID-19-induced anosmia, which conceivably should not be deemed a universal diagnosis. The words of the WHO director-general [1] however, indicate that misuse of the term "pandemic" can cause "unreasonable fear" describing a global threat that needs to be confronted cautiously. In this regard, recognition of abnormal MRI findings related to the olfactory apparatus can prevent misdiagnosis in cases resembling viral olfactory neuropathy. Correct diagnosis of the cause of olfactory deficit may indeed have important implications for the prediction of the natural course of current galloping A, Axial T2-weighted brain MR image shows bilateral areas of high signal intensity (arrows) in rhinobase adjacent to the olfactory sulci (arrowheads).

World Health Organization. WHO Director-General's opening remarks at the media briefing on COVID-19 -11

National Center for Immunization and Respiratory Diseases (NCIRD), division of viral diseases

COVID-19 anosmia reporting tool: Initial findings

Anosmia and dysgeusia in the absence of other respiratory diseases: Should COVID-19 infection be considered?

Anosmia in COVID-19 Associated with Injury to the Olfactory Bulbs Evident on MRI

Olfactory bulb magnetic resonance imaging in SARS-CoV-2-induced anosmia: the first report