There is increasing observation by doctors treating patients with COVID-19 in New York that with fever, cough, and shortness of breath, another symptom appears: some are confused, to the point of not knowing where they are, nor what is the current year.
This loss of bearings is sometimes linked to the lack of oxygen in the blood, but in some patients, the level of confusion seems to be out of proportion compared to the level of affection of their lungs.
For Jennifer Frontera, a neurologist at Langone University Hospital in Brooklyn, the question arises of the impact of the new coronavirus on the brain and nervous system.
Studies are beginning to describe the phenomenon. In the journal of the American Medicine Association (Jama), last week, doctors reported that 36% of 214 Chinese patients had neurological symptoms, ranging from loss of smell to nerve pain, and up to seizures and strokes.
In the New England Journal of Medicine, the top-rated American medical journal, French doctors in Strasbourg described that more than half of 58 ICU patients were confused or agitated. Brain scanners revealed possible inflammations.
Viruses can affect the brain in two main ways, says Michel Toledano, a neurologist at the Mayo Clinic in Minnesota.
The first is by triggering an abnormal immune response called “cytokine storm”, which causes inflammation of the brain: this is called autoimmune encephalitis.
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 speculate that the nose could be the path to the brain since the loss of smell is common in many COVID-19 patients. But this is not verified, and many patients who lose their sense of smell do not have serious neurological problems.
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 in the International Journal of Infectious Disease.
He suffered from confusion and seizures and imagery of his brain showed inflammation. But the test is not yet validated and the scientists remain cautious.