The Novel Coronavirus (COVID-19) is a contagious disease, which is mainly known to infect the upper respiratory system of an individual. It is also lethal to people with a weak immune system, with chronic and kidney diseases, and to elders and pregnant women. But do you know COVID-19 can also cause nervous system disorder?
The central nervous system (CNS) includes the brain and the spinal cord. In a recent study, it was found that in addition to the respiratory symptoms, around 36.4 per cent of COVID-19 patients also developed some neurological symptoms such as lack of consciousness, headache and paresthesia. The study also says that severely infected patients are more likely to develop such neurological symptoms than people with mild to moderate symptoms.  On 4 March 2020 in Beijing Ditan Hospital, the first case of viral encephalitis due to COVID-19 attacking CNS was reported. The cerebrospinal fluid of the patient was found to be infected with the virus stating that COVID-19 has the potential to cause damage to the nervous system.
There are many neuroviruses known to affect the functionality of the nervous system and cause neurological damage such as severe encephalitis and toxic encephalopathy. They invade the nervous tissues and cause infections. A study says SARS coronavirus could induce severe neurological problems such as encephalitis and polyneuropathy. In many SARS autopsy, signs of cerebral oedema and meningeal vasodilation (migraine) was also detected.
Also, changes in neurons and nerve fibres along with SARS-CoV particles were detected in the brain.  COVID-19 is a crown-shaped virus with large spikes. It is 79.5 per cent genetically similar to SARS-Cov which has occurred in 2003. Due to the similarity between SARS-Cov and COVID-19, it is said to have similar neurological symptoms. Moreover, COVID-19 patients have also reported sudden symptoms like loss of smell (anosmia) and loss of taste (dysgeusia). This shows that novel coronavirus has the potential to harm the nervous system of the body.
How COVID-19 Infects The Central Nervous System
1. Peripheral tissues
The invasion of viruses first starts in the peripheral tissues which further spreads to the peripheral nervous system (PNS) and the CNS. Though CNS is protected by an effective immune response, some high efficacy viruses like COVID-19 and SARS can reduce its functionality and enter the cerebrospinal fluid or brain. 
2. Olfactory nerve
Coronavirus can enter into the brain and spinal cord through the olfactory nerve or nasal chamber. After infection the nasal cells, it gets transferred to the brain and the cerebrospinal fluid.
3. Infection of the lungs
When coronavirus infects the lungs, it causes the disposition of transparent liquid in the alveoli which reduces the supply of oxygen to other body parts. Due to lack of oxygen to the CNS, hypoxia is developed leading to swelling of the brain, cerebral vasodilation, headache and other CNS disorders. 
4. Immune system injury
When pneumonia occurs in COVID-19 patients, the body’s immune response against the pathogens suddenly spikes up causing abnormality in its function. This causes damage to the immune system allowing viruses to enter the CNS.