key: cord-0857053-g8nrmp4w authors: Finsterer, Josef; Scorza, Fulvio A title: Letter to the Editor: Ischemic Stroke of the Corpus Callosum after SARS-CoV-2 Vaccination date: 2021-10-14 journal: J Korean Med Sci DOI: 10.3346/jkms.2021.36.e288 sha: a11374f94e9378894c00ab1b24cb74f72604202d doc_id: 857053 cord_uid: g8nrmp4w nan To exclude acute, disseminated encephalomyelitis (ADEM) as a differential of the callosal lesion, application of contrast medium is missing. Usually, ADEM lesions show up with gadolinium enhancement. 4 Additionally, MRI of the spinal cord should have been carried out to confirm or exclude a spinal lesion. Furthermore, follow-up MRI after treatment with steroids, is required to document the resolution of the abnormality. Missing are the serum and cerebro-spinal fluid (CSF) levels of cytokines, such as IL-8, IL-6, IL-1A, and TNF-alpha. Overall, the elegant study has some limitations which challenge the results and their interpretation. These limitations should be addressed to further strengthen the conclusions. © 2021 The Korean Academy of Medical Sciences. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https:// creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Taeho First, the diagnosis of CLOCCs can be made based on imaging and clinical findings, and not necessarily on a diagnosis of exclusion. With the widespread use of MRI, many cases of various conditions of CLOCCs have been reported. According to Jay Starkey et al., 1 CLOCCs shows typical imaging findings such as a small round or oval shape lesion located in the center of the splenium. As mentioned in prior studies, ischemic infarction and acute disseminated encephalomyelitis (ADEM) of the corpus callosum tend to be asymmetric and more aggressive. Increasing evidence suggests that CLOCC has distinctive MRI findings compared to both ischemic stroke and ADEM. The patient's diagnosis was made based on common and typical findings of CLOCCs. Due to the nature of cytotoxic edema, the MRI findings could be interpreted as an ischemic lesion of the corpus callosum. However, cytotoxic edema is not only seen in cerebral ischemia but also inflammatory conditions associated with a brain infection, encephalitis, metabolic abnormality, brain tumor, seizure, trauma, hemorrhage, vaccination, and COVID-19. [2] [3] [4] In addition, CLOCCs is not always reversible, which implies that follow-up MRI might be unnecessary to confirm the diagnosis. 5 As mentioned previously, the patient's initial MRI showed a lack of enhancement on the lesion (Fig. 1A-D) . In our prior report, the patient was a healthy young man without any underlying diseases, thus no notable risk factors for ischemia and there were no abnormal findings on neurological examination. This was another clinical clue that suggested against ischemic stroke. Ischemic stroke of the corpus callosum has more distinguishing clinical symptoms including cognitive impairment, complete or incomplete motor aphasia, language disorder, facial and limb paralysis, and alien hand syndrome. 6,7 The patient's initial magnetic resonance angiography scan also showed no notable abnormality. Second, in all likelihood, it is credible that CLOCCs could be secondary to cerebral venous thrombosis (CVT), which also has distinguishable findings such as clot signs and vasogenic and cytotoxic edema around the lesion, all not found in our index case. 8, 9 On the contrary, in our case, it is important to point out that the patient's initial D-dimer level was < 0.1 mg/L, which is known to carefully screen CVT with Vaccine-induced immune thrombocytopenia and thrombosis (VITT). 10 Furthermore, we are rather reluctant to fully agree on the notion that the mRNA vaccination is a risk factor for CVT. 11 VITT tends to appear after recombinant adenovirus vaccination rather than mRNA vaccine. 12 The patient's initial cardiac enzyme levels (CK-MB, Tn-I, pro-BNP) were not elevated and there were no chest pains or other symptoms suggestive of myocarditis. Third, we appreciate your generous suggestions to perform advanced diagnostic modalities including echocardiography, cardiac MRI, whole spine MRI, and cerebrospinal fluid cytokine test. Since the patient's headache completely resolved within a day of being admitted to a tertiary hospital, further imaging and laboratory examinations were not performed during admission. The purpose of this study was to suggest the possible need for further evaluation including an MRI scan of a healthy individual presenting with fever and headache after COVID-19 mRNA vaccination to identify adverse reactions. The World Health Organization's definition of adverse reaction is a response to a drug that is noxious, unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis, or therapy of disease, or the modifications of physiological function. 13 Cytotoxic lesion of the corpus callosum (CLOCCs) after SARS-CoV-2 mRNA vaccination A COVID-Positive 52-year-old man presented with venous thromboembolism and disseminated intravascular coagulation following Johnson & Johnson vaccination: a case-study Cytotoxic lesions of the corpus callosum that show restricted diffusion: mechanisms, causes, and manifestations Cytotoxic lesion of the corpus callosum in an adolescent with multisystem inflammatory syndrome and SARS-CoV-2 infection Diffusion-weighted imaging of acute excitotoxic brain injury COVID-19 and involvement of the corpus callosum: potential effect of the cytokine storm? Reversible lesion in the splenium of the corpus callosum Neurotoxicity of carbon monoxide targets caudate-mediated dopaminergic system Clinical features of acute corpus callosum infarction patients Reversible splenial lesion syndrome (RESLES) coinciding with cerebral venous thrombosis: a report of two cases Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls Vaccine-induced immune thrombocytopenia and thrombosis (VITT) Vaccine-induced immune thrombotic thrombocytopenia and cerebral venous sinus thrombosis post COVID-19 vaccination; a systematic review COVID-19 vaccine-associated immune thrombosis and thrombocytopenia (VITT): diagnostic and therapeutic recommendations for a new syndrome International drug monitoring: the role of national centres We are grateful for the opportunity to report follow-up images that show resolution of previous lesions and no significant abnormalities after 3 months from the index event ( Fig. 1E-H) . Unfortunately, pressed for time, our previous paper was published without relevant followup MRI images but we hope that the images included in this report would be sufficient in supporting our last conclusion.