COVID-19 is a highly unpredictable virus. It can infect cells outside the respiratory system, and the nerve cells are no exception.
COVID-19 is a highly unpredictable virus. It affects people of all ages and it manifests in extremely varied ways. The media has informed till exhaustion about the main respiratory symptoms of the disease: shortness of breath, cough, and fever. However, this virus can also infect cells outside the respiratory system, and the nerve cells are no exception.
Research is still lacking, but so far it is believed that neurological symptoms associated with COVID-19 are the result either of these two paths: direct or indirect infection of the brain cells.
In some cases, the virus reaches directly to the brain. COVID-19 is mostly hosted by cells located in the nose and mouth. The nose acts as a door through which external stimuli can reach directly to the brain. The olfactory bulb, a small structure in the ventral side of the frontal lobes, is located just above the nasal cavity. Therefore, infected cells in the nose can travel through this passageway and easily reach the olfactory bulb. Affection to the olfactory bulb explains the sudden loss of smell and taste of some patients with COVID-19.
In other cases, neurological symptoms result from more complex and indirect processes. When the body is fighting viral infections and the immune system is hyperactivated, inflammation to the brain is produced. This seems to be happening with some patients with COVID-19. When the immune system hyperactivates, it releases an excessive number of immune cells and other compounds called cytokines. These chemicals can cause several damages to the brain:
Headaches and dizziness.
Weakening and rupture of blood vessels, which cause hemorrhagic strokes, and the formation of blood clots and thrombi, which produces ischemic strokes.
Encephalitis and Guillain-Barré Syndrome have been seen in some patients with COVID-19. Encephalitis is an inflammatory process that causes the swelling of the brain, while Guillain–Barré Syndrome is a neurological disorder where the immune system mistakenly attacks nerve cells, resulting in muscle weakness and paralysis.
When the virus crosses the blood brain barrier and replicates inside neurons, cell death is imminent. Some cognitive impairments associated with COVID-19 are: changes in consciousness, disorientation, inattention, slow speed processing, movement disorders, seizures, and hallucinations. These symptoms have been seen in acute stages and after recovery.
It was believed that neurological complications of COVID-19 affected only older people with comorbid pathologies, but they have also been found in young healthy people.
Long-term impact to the brain is still unknown, as well as the impact treatment procedures, such as mechanical ventilation, could have. There is a lot to learn about COVID-19, but we can be sure of one thing: it is a mortal virus that does not discriminate against anyone.