Background and Purpose: Case series indicating cerebrovascular disorders in coronavirus disease 2019 (COVID-19) have been published. Comprehensive workups, including clinical characteristics, laboratory, electroencephalography, neuroimaging, and cerebrospinal fluid findings, are needed to understand the mechanisms. Methods: We evaluated 32 consecutive critically ill patients with COVID-19 treated at a tertiary care center from March 9 to April 3, 2020, for concomitant severe central nervous system involvement. Patients identified underwent computed tomography, magnetic resonance imaging, electroencephalography, cerebrospinal fluid analysis, and autopsy in case of death. Results: Of 32 critically ill patients with COVID-19, 8 (25%) had severe central nervous system involvement. Two presented with lacunar ischemic stroke in the early phase and 6 with prolonged impaired consciousness after termination of analgosedation. In all but one with delayed wake-up, neuroimaging or autopsy showed multiple cerebral microbleeds, in 3 with additional subarachnoid hemorrhage and in 2 with additional small ischemic lesions. In 3 patients, intracranial vessel wall sequence magnetic resonance imaging was performed for the first time to our knowledge. All showed contrast enhancement of vessel walls in large cerebral arteries, suggesting vascular wall pathologies with an inflammatory component. Reverse transcription-polymerase chain reactions for SARS-CoV-2 in cerebrospinal fluid were all negative. No intrathecal SARS-CoV-2-specific IgG synthesis was detectable. Conclusions: Different mechanisms of cerebrovascular disorders might be involved in COVID-19. Acute ischemic stroke might occur early. In a later phase, microinfarctions and vessel wall contrast enhancement occur, indicating small and large cerebral vessels involvement. Central nervous system disorders associated with COVID-19 may lead to long-term disabilities. Mechanisms should be urgently investigated to develop neuroprotective strategies.

Coronavirus disease 19 (COVID‐19) is a rapidly evolving pandemic caused by the coronavirus Sars‐CoV‐2. Clinically manifest central nervous system symptoms have been described in COVID‐19 patients and could be the consequence of commonly associated vascular pathology, but the detailed neuropathological sequelae remain largely unknown. A total of six cases, all positive for Sars‐CoV‐2, showed evidence of cerebral petechial hemorrhages and microthrombi at autopsy. Two out of six patients showed an elevated risk for disseminated intravascular coagulopathy according to current criteria and were excluded from further analysis. In the remaining four patients, the hemorrhages were most prominent at the grey and white matter junction of the neocortex, but were also found in the brainstem, deep grey matter structures and cerebellum. Two patients showed vascular intramural inflammatory infiltrates, consistent with Sars‐CoV‐2‐associated endotheliitis, which was associated by elevated levels of the Sars‐CoV‐2 receptor ACE2 in the brain vasculature. Distribution and morphology of patchy brain microbleeds was clearly distinct from hypertension‐related hemorrhage, critical illness‐associated microbleeds and cerebral amyloid angiopathy, which was ruled out by immunohistochemistry. Cerebral microhemorrhages in COVID‐19 patients could be a consequence of Sars‐ CoV‐2‐induced endotheliitis and more general vasculopathic changes and may correlate with an increased risk of vascular encephalopathy.

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