The most common neurological complaints in COVID-19 are headache, loss of sense of smell and taste, stroke, impairment of consciousness, and seizure, according to a review of studies that may lead to improved clinical outcomes and better treatment protocol for coronavirus infection.
According to researchers from the Yale School of Medicine in the US, while the respiratory symptoms of COVID-19 are described, the neurological complications of infection with the novel coronavirus, SARS-COV-2, is not well known.
The review research, published in the Journal of the American Medical Association, noted the possible mechanism by which SARS-CoV-2 caused neurological symptoms by comparing it with similar coronaviruses MERS-CoV and SARS-CoV-1, which are known to affect the central nervous system (CNS).
In the study, the scientists summarised available information regarding novel coronavirus infection of the nervous system and identified the potential tissue targets and routes of entry of SARS-CoV-2 into the CNS.
Citing earlier research, published in the New England Journal of Medicine, they said neurologic symptoms reported in 49 of the study’s 58 patients, included confusion and brain damage or encephalopathy.
Based on studies of MERS-CoV and SARS-CoV-1, the scientists said the novel coronavirus may enter the nervous system by several routes, including via transfer across the junctions of infected neurons, and via the olfactory nerves connecting the nose and the brain, involved in producing the sense of smell.
The researchers believe the virus may also infect the CNS by spreading across the inner walls of blood vessels throughout the body. They postulated that the virus may also reach parts of the brain by infecting immune cells called leukocyte which can cross the protective filter membrane called the blood-brain barrier.
This ‘Trojan horse’ mechanism of infecting the brain is seen in HIV, the scientists said. According to the study, the most common neurologic complaints in COVID-19 are the loss of sense of smell and taste (anosmia and ageusia), headache, stroke, impairment of consciousness, seizure, and brain damage.
However, the scientists said further studies involving brain scans and testing of CNS tissue will be crucial to understanding the biological process of the disease in the nervous system. “Early detection of neurological deficits may lead to improved clinical outcomes and better treatment algorithms,” the scientists wrote in the study.