Studies reveal impact of virus on all levels of nervous system

NEW DELHI: 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 has added the sudden loss of smell and taste to the list of Covid-19 symptoms 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.

“It’s important for the general public and physicians to be aware of this, because a Sars-cov-2 infection may present (itself) with neurologic symptoms initially, before any fever, cough or respiratory problems occur,” said the lead author of the review, Dr Igor Koralnik, professor of neurology at the Northwestern University Feinberg School of Medicine in Chicago, in a statement.

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.

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.

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.