COVID-19 pandemic is the largest and the most severe outbreak since the 1918 Spanish flu. Most of its early symptoms are related to the respiratory system but there seems to be a noticeable number of patients who develop symptoms related to the Nervous system, both central and peripheral. Large series from Wuhan, China has shown that 36% of hospitalized patients developed neurological manifestations and these can include the following:
- Anosmia and Aguesia: Loss of sense of smell (Anosmia) and taste (Augesia) has been seen as an initial presentation in the presence of or absence of other symptoms of COVID-19. The fact that it can occur without other classical COVID-19 manifestations makes it unique and has been used as a screening test for otherwise asymptomatic COVID-19 patients. This is most likely due to the direct involvement of the olfactory nerve by the Coronavirus. These symptoms, however, are short-lived and most patients regain their sense of smell and taste as they recover from Coronavirus.
- Headache is the key symptom and can be attributed to low oxygen levels in the brain; secondary to involvement of the lungs or maybe a virus related to swelling or inflammation of brain tissue and meninges (covering of the brain). Headache has been seen in 13% of patients with COVID-19. Those patients who have pre-existing primary headaches like migraine and tension-type headaches also have worsened in COVID times mainly attributed to stress/panic created by the pandemic. So, it’s difficult to differentiate primary headaches from COVID-19 symptoms; however, any new onset of headache with fever, cough, body aches, loss of taste, and smell should be evaluated for COVID-19.
- Neuromuscular (Nerve and Muscle): Muscle involvement in the form of muscle tiredness, soreness and pain which is due to the inflammatory response in muscles or direct muscle damage by the virus. In severe cases, muscle protein myoglobin is released in the blood leading to kidney failure. Peripheral nervous system involvement can present as Gullian Bare Syndrome (GBS), a rapidly progressive limb weakness which is a polyradiculopathy (multiple nerve bundle involvement). GBS like illness develops 7 (range 7-24) days after the onset of respiratory symptoms. Facial palsy, a weakness of the one side of the face with an inability to close the eye of the affected site of varying degrees has been reported as COVID-19 manifestation especially when associated with fever, cough, etc.
- Brain stroke: A review of the literature has shown the occurrence of ischemic and hemorrhagic strokes in COVID-19 patients. The incidence is more eminent in patients with comorbidities (hypertension, diabetes, and high cholesterol). It’s been postulated that the virus binds to the receptors where drugs to lower blood pressure bind, thus predisposing to uncontrolled hypertension and brain haemorrhage. Brain strokes due to blood clots occur in secondary to prothrombotic state which makes the blood thicker or stickier and can lead to a shower of clots or territorial strokes. Few studies have also shown that young patients who lack risk factors have seen to have severe strokes due to clots in major/large blood vessels of the brain.
- Cerebrovascular symptoms: Swelling or inflammation of the brain with raised pressure in CSF (fluid in the brain) due to immune response to COVID-19 can present as confusion, abnormal behaviour, and seizures. Though this manifestation is not that commonly seen; but when encountered can be severe and leads to morbidity if not treated early.
The COVID-19 pandemic has overwhelmed health care systems all over the world and more so in countries like India since its emergence in December 2019. Despite, its most characteristic manifestations involve lungs, patients with COVID-19 have also shown neurological manifestations which have led to more mortality and morbidity. How it causes neurological involvement by direct involvement of medullary centers in the brain, due to inflammatory reaction remains unclear. However, identification of neurological manifestations is a step forwards in better understanding the virus and thus treating the patients affected by the pandemic.