On 8 June, Dr Majid Fotuhi and colleagues published a review article in the Journal of Alzheimer’s disease, summarizing the evidence for neurological manifestations of COVID-19 and proposing a three-stage classification scheme for neurological symptoms in COVID-19. The COVID-19 pandemic has expanded rapidly across the globe, with over 8 million cases and 486,000 deaths reported to date. Initially presented as a respiratory disease, recent studies and case reports indicate that there are also many neurological manifestations of COVID-19, including loss of smell (anosmia), seizures, stroke, delirium and paralysis, among other symptoms. In their review article, Dr Fotuhi and colleagues sought to summarise these studies and case reports, focusing on how SARS-CoV2 (the virus that causes COVID-19) impacts the central and peripheral nervous systems.
Their review of the literature revealed that dysfunction of smell and taste was widely reported across studies; for example, an Italian study showed that over 64% of patients with mild COVID-19 reported an impaired sense of smell. Cerebrovascular disease was also identified in several studies, with 13 of 221 patients in one study having imaging-confirmed ischemic infarcts (strokes) in large or small cerebral vessels. Several case reports described patients presenting with seizures, confusion or delirium, often associated with cerebrovascular changes. The authors described some of the pathophysiological mechanisms underlying these symptoms, including inflammatory changes in cerebral blood vessels (which express ACE2, the receptor for SARS-CoV2) and ‘cytokine storms’ that can cause more widespread damage. They postulated that direct infection of brain cells by SARS-CoV2 may also play a role, however underline that there is currently insufficient scientific evidence to support this theory.
In their review, the authors propose a classification scheme for neurological involvement of COVID-19. In Stage I, SARS-CoV2 is restricted to the nasal or gustatory epithelium, which causes taste and smell impairments, but few severe symptoms. In Stage II, SARS-CoV2 is more widespread and causes a more robust inflammatory response, leading to vascular changes that predispose patients to strokes. In Stage III, SARS-CoV2’s cytokine storm damages the blood-brain barrier, resulting in greater infiltration of inflammatory cells and more severe neurological involvement, including strokes, delirium and seizures. Finally, the authors called for neurologists to be mindful of COVID-19 issues that can directly impact their care of people with Alzheimer’s disease and other neurological disorders, such as the increased risk of stroke and delirium. The original article was published in the Journal of Alzheimer’s Disease and can be found here:
https://content.iospress.com/articles/journal-of-alzheimers-disease/jad200581
