What impacts of SARS-CoV-2 on the brain?

Fever, cough, shortness of breath or even loss of smell are the known symptoms of Covid-19. Researchers are now questioning the impact of SARS-CoV-2 on the brain and nervous system, with some patients with the virus losing their bearings and showing signs of confusion.

New York doctors treating patients with Covid-19 increasingly observe that with the fever, cough and shortness of breath, another symptom appeared. Some people are confused, to the point of not knowing where they are or what the current year is. This loss of bearings is sometimes linked to the lack ofoxygen in the blood, but in some patients the level of confusion seems to be out of proportion to the level of affection of their lungs. For Jennifer Frontera, neurologist at Langone University Hospital in Brooklyn, the question arises of the impact of the new coronavirus on the brain and the nervous system.

Possible brain inflammation

Studies are beginning to describe the phenomenon. In the review ofAmerican Medicine Association (Jama), doctors reported last week that 36% of 214 Chinese patients had neurological symptoms, ranging from loss ofsmell Has pains nervous, and up to seizures and accidents cerebrovascular (Stroke).

In the New England Journal of Medicine, the most highly rated American medical journal, French doctors in Strasbourg described that more than half of 58 intensive care patients were confused or agitated. Of scanners brains have revealed possible inflammations.

" Everyone says it's a problem of breathing, but it also affects something very precious to us, the brain, told AFP S. Andrew Josephson, head of the neurology at the University of California San Francisco. If you feel confused, have trouble thinking, these are good reasons to see a doctor, he adds. The old idea that you should only come if you are out of breath is no longer valid. "

Virologists are not entirely surprised that the new coronavirus, SARS-CoV-2, may affect the brain and nervous system, as this link has been observed with others virus, including the virus AIDS, the HIV. Viruses can affect brain in two main ways, says Michel Toledano, a neurologist at the Mayo Clinic in Minnesota. The first is by triggering a immune response abnormal called " thunderstorm of cytokine ", Which causes inflammation of the brain: this is called encephalitis autoimmune. The second is by direct infection of the brain: this is called viral encephalitis. The brain is protected by what is called the blood-brain barrier : its role is to block intruders, but it can be pierced.

Some hypothesize that the nose could be the pathway to the brain, since the loss ofsmell is common to many Covid-19 patients. But this is not verified, and many patients who lose their sense of smell do not have serious neurological problems.

Lasting troubles?

The main track is actually that of the overheated immune response. To find out, the virus should be detected in the cerebrospinal fluid. This was done once, in a 24-year-old Japanese man, whose case was described inInternational Journal of Infectious Disease. He suffered from confusion and convulsions and imagery of his brain showed inflammation. But the Review is not yet validated and the scientists remain cautious.

To unravel these mysteries, Jennifer Frontera, who teaches at New York University School of Medicine, is collaborating on an international research project aimed at standardizing data collection. His own team has documented seizures in Covid-19 patients who never had them before they fell ill. The researchers also observed tiny cerebral hemorrhages described as "new". They also want to take cerebrospinal fluid from a 50-something whose matter white brain is severely affected. But these levies, just like the MRI, are difficult to do on patients on an artificial respirator. And as the majority die, there is little study of neurological damage.

Those who survive, however, end up consulting neurologists. " We see a lot of patients in states of confusion "Rohan Arora, a neurologist at Long Island Jewish Forest Hills Hospital, told AFP. He claims that 40% of coronavirus survivors are affected. It is not known if these disorders are lasting. The transition to intensive care is, in itself, a source of confusion, especially due to medication. But the neurologist finds that the return to normal, for Covid patients, seems to take longer than for those who survived a heart attack or one Stroke.

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