E-Paper
Studies reveal impact of Sars-CoV-2 virus on all levels of nervous system
Based on previous experience with coronaviruses, Sars-CoV-2 could impact the nervous system in three ways: by direct invasion, by consequence of other medical conditions such as stroke, and post-infection diseases
A review of over 50 studies published on June 11 has revealed that the Sars-CoV-2 virus that causes the coronavirus disease (Covid-19) affects almost every level of the nervous system and may lead to strokes, seizures and muscular pains in people who catch the infection.
Some Covid-19 patients may exhibit mild symptoms like headache, dizziness, reduced alertness, difficulty in concentrating and disorders of smell and taste, according to the review that comes at a time when India is considering adding the sudden loss of smell and taste to the list of Covid-19 symptoms, such as fever and shortness of breath, to watch out for.
Based on previous experience with coronaviruses, Sars-CoV-2 could impact the nervous system in three ways: by direct invasion, by consequence of other medical conditions such as stroke, and post-infection diseases such as the Guillain-Barre Syndrome, a disorder of the immune system, according to the review published in the journal Annals of Neurology.
Other diseases caused by coronaviruses, including the Severe Acute Respiratory Syndrome (Sars) and the Middle East Respiratory Syndrome (Mers), led to few cases with neurological symptoms. Those two viruses affected 10,500 people.
By Saturday, June 13, Covid-19, which first manifested itself in the central Chinese city of Wuhan at the end of 2019, had affected at least 7 million people worldwide.
“Head ache, dizziness, disturbance of smell and taste, difficulties with memory can occur before any other respiratory symptoms. This is very important since those people should be tested for Sars-CoV-2 and if positive, they should be isolated and their contacts should be traced to avoid spread of the virus in their family and community.,” said the lead author of the review, Dr Igor Koralnik, professor of neurology at the Northwestern University Feinberg School of Medicine in Chicago. “It appears likely that this should also be the case in India, but it is possible that physicians focus on the respiratory disease first and that neurological manifestations are not recorded systematically. It is also possible that different viral strains affect people in India compared to those in the rest of the world or the different ethnic background of the population may affect the spectrum of neurological manifestations of Covid-19. Whether this is the case in India has to be determined through systematic analysis.”
Respiratory distress is still considered to be a defining symptom of Covid-19. “Several ongoing studies in Italy are finding strong evidence that this virus can affect the peripheral nervous system (sensory), but in some patients, who already have a weak system, it can affect the central nervous system (brain and spinal cord) and affect their cognition and memory,” said Dr Ramesh K Mishra, professor and head of the Centre for Neural and Cognitive Sciences (CNCS) at the University of Hyderabad, who reviewed the study.
More studies are needed on the cognitive consequences of those who survive the infection, Mishra said. “There have been cases of cognitive degenerative disorders previously in HIV and Ebola, but only a few cases. It is because these patients live long now that these have been observed.”
Mishra cited a study conducted in Wuhan and published in JAMA Neurology, a peer-reviewed medical journal, that found nervous system symptoms in 36% of 214 Covid-19 patients in three hospitals.
“The Northwestern University researchers are basing their review around it because they themselves have not done much. They are telling the government that the neuro team should be on high alert. That should be our aim also,” he said.
“Serious neurological manifestation is stroke, which is rare,” said Dr Gagandeep Singh, head of the department of neurology at Dayanand Medical College & Hospital in Ludhiana, and secretary of the Indian Academy of Neurology.
In India, such cases have been reported from Chennai and Delhi. “We are currently pooling in anonymised data on the occurrence of stroke in Covid-19 patients,” Dr Singh said.
The ACE receptors, to which Sars-Cov-2 locks on to enter and infect human cells, are also present in the brain and blood vessels, which become inflamed, leading to endotheliitis, or inflammation in the inner walls of the arteries, said Dr Rajinder K Dhamija, head of the neurology department at the Lady Hardinge Medical College & Hospital in Delhi.
“This may form clots that can lead to stroke,” Dr Dhamija said. “There is literature to show that Covid-19 is beyond cough and fever. We should proactively probe the history of the patient.”
