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To the Editor:We performed a literature review on viral epidemics and pandemics, including the severe acute respiratory syndrome (SARS), the Middle East respiratory syndrome (MERS), influenza H1N1, and the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with the goal of identifying the neurological symptoms, signs, and complications of these infections within the context of the COVID-19 pandemic (Figure).Of 16 articles that included 8042 patients with H1N1, neurological involvement was reported in 1286 patients (15.99%). Excluding headaches, 771 patients had neurological involvement (9.6%) (Table 1). Of 8 articles consisting of 1128 patients with MERS, 323 patients (28.6%) had neurological findings and 170 patients (15.07%) without headache. Of 5 articles with 1251 patients with SARS, 187 patients (14.95%) were reported to have neurological involvement and 6.2% (n = 78) with the exclusion of headache. Of 17 articles on 5335 patients with COVID-19, 744 patients were reported to have neurological signs, symptoms, FIGURE. Flow diagram of study selection criteria and results.or sequelae (13.9%) to date, with a rate of 2.47% when headache was excluded (n = 132) (Table 2).At this time, the neurological complications of COVID-19 are not fully understood, but reports of prominent neurological symptoms and complications are beginning to emerge. 1 The current incidence of neurological findings with COVID-19 is relatively low, but as data from prior epidemics show, particularly prior coronavirus-related epidemics, the rate is likely to further increase. Neurological manifestations, including headache, dizziness, altered level of consciousness, focal neurological deficits, cranial nerve involvement, 2 seizures, and to a lesser extent meningoencephalitis, 3 more severe necrotizing encephalopathy, 4 cerebral edema, and stroke, 5 have been reported with the recent viral epidemics. Importantly, with prior epidemics (Table 3), there are also several reports of patients developing neurological sequelae months to weeks later, including cerebellitis, 6,7 neuropathy, 8 Guillain-Barré syndrome, 9 postinfluenza myositis, 10 and postviral Parkinsonism. 11 Coronaviruses are thought to disseminate to the central nervous system (CNS) through either hematogenous spread, retrograde neuronal dissemination, or direct invasion of the olfactory epithelium. 12

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BACKGROUND AND PURPOSE: T2 signal and FLAIR changes in patients undergoing stereotactic radiosurgery for brain AVMs may occur posttreatment and could result in adverse radiation effects. We aimed to evaluate outcomes in patients with these imaging changes, the frequency and degree of this response, and factors associated with it. MATERIALS AND METHODS: Through this retrospective cohort study, consecutive patients treated with stereotactic radiosurgery for brain AVMs who had at least 1 year of follow-up MR imaging were identified. Logistic regression analysis was used to evaluate predictors of outcomes. RESULTS: One-hundred-sixty AVMs were treated in 148 patients (mean, 35.6 years of age), including 42 (26.2%) pediatric AVMs. The mean MR imaging follow-up was 56.5 months. The median Spetzler-Martin grade was III. The mean maximal AVM diameter was 2.8 cm, and the mean AVM target volume was 7.4 mL. The median radiation dose was 16.5 Gy. New T2 signal and FLAIR hyperintensity were noted in 40% of AVMs.