1. Does COVID-19 affect the nervous system?
Yes. But symptoms involving the nervous system are not seen in all patients. Those with severe disease (requiring an ICU admission) and people in the older age group (more than 50 years of age) are more likely to have neurological disease. A study published in the journal JAMA Network Open reported 80% of patients who required hospitalization had neurological symptoms. Fortunately, most patients have only mild to moderate symptoms. Rarely, even children have been reported to have neurological symptoms. The brain can be involved indirectly or directly by the virus. Indirect involvement is by affecting the lungs (pneumonia) and decreasing the oxygen levels, which the brain needs dearly for its functioning. Similarly, involvement of the heart can decrease blood pressure, and this can cause neurological symptoms. We will now see how the virus directly affects the brain.
2. How does the virus enter the brain?
We know that the Coronavirus is a respiratory virus and affects the respiratory system (nose, throat and lungs) mainly. However this virus can also enter into the nervous system through the blood or through olfactory nerves (nerves of smell sensation) directly into the brain.
3. What does it do to the nervous system?
Once inside the brain, the main targets of this virus are the blood vessels (which carry blood to the brain) and the inflammatory cells (which help
in fighting against infections and protecting the brain). By damaging the blood vessels, this virus promotes the formation of clots inside them,
which leads to a stroke. By over-activating the inflammatory cells, it causes brain damage by a process called ‘cytokine storm’, in which these
cells are made to produce too much of the chemicals which are helpful in fighting an infection (the invader), so that these chemicals start damaging
the host’s organs. This process leads to swelling of the brain (encephalitis) which leads to seizures (fits) and drowsiness or confusion (altered consciousness).
4. What are the common symptoms?
Loss or decrease in the sense of smell and taste (called anosmia and ageusia) are the most common symptoms. Headaches, drowsiness, fits, strokes and paralysis of the body starting in the legs, muscle pain and weakness are other possible symptoms pointing to neurological involvement. We should remember that some symptoms can appear or persist few days or weeks after recovery from COVID-19, for example, memory loss (amnesia) or weakness (paralysis).
5. Are these conditions treatable?
Yes. Most of these conditions are treatable, if identified early. Since the inflammatory cells are over-activated in this disease, doctors frequently use anti-inflammatory drugs like steroids. Strokes are managed with medicines to reduce clot formation (anti-platelets and anti-coagulants). It should be noted that this has to go hand-in-hand with treatment of the lung disease (pneumonia), since the lungs are the most severely affected organs in COVID-19.
6. How long do these symptoms last?
Most of these symptoms resolve in 2-4 weeks, which means in about a month after recovery, you should be free from neurological symptoms.
However some patients have lingering problems, which last up to months after recovery from COVID-19. These include brain fog (difficulty concentrating, thinking and persistent fatigue), memory loss, headache, dizziness, distortion or loss of smell and taste.
Dr Shivan Kesavan,
Consultant- Paediatric Neurologist,
Dr Mehta Hospitals, Chetpet