Covid-19 and Epilepsy

Neurological complications following COVID-19 are being reported in large numbers .Among 236 379 patients diagnosed with COVID-19, the estimated incidence of a neurological or psychiatric diagnosis in the following 6 months was 33•62% as reported by Maxime Taquet  et al in Lancet Psychiatry 2021; 8: 416–27.

The neurologic manifestations of the disease can be classified into central nervous system (CNS) symptoms and peripheral nervous system (PNS) symptoms.The common neurological conditions associated with  Covid-19 infection include:

• Delirium , 
• Confusion ( Brain Fog)
• Loss of sense of smell and taste,
• Weakness of limbs due to myelin loss of nerves
• Stroke
• Epilepsy

Mechanism of Central Nervous System (CNS) Involvement
SARS-CoV-2 uses its spike protein (S-protein) to bind to angiotensin-converting enzyme 2 (ACE2), which  the functional receptor of the virus. This  results in cleavage of the S-protein. This results in attachment of the virus to the human cell membrane and subsequent   entry of the viral genome into the cell. The host cell  then propagates the virus as well as  mounts the immune response .

 There are three proposed routes for direct CNS invasion and injury, as well as several suggested mechanisms for indirect neurologic injury (Nordvig AS et al. Potential neurological manifestations of COVID-19. Neurol Clin Pract. 2020 Jun 30: Epub)

 The proposed direct CNS mechanisms are
1. Infection of the peripheral nerve, which may occur via entry through the olfactory nerve covering by way of the olfactory nerve to the olfactory bulb, entry into the neurons in a direct manner, and retrograde nerve transmission;
2. Disruption of the blood-brain barrier (BBB) .BBB separates the brain from the general circulation.
3. The Trojan horse entry method, wherein virally infected immune cells covertly pass through the BBB to the CNS. In addition, the virus can exert injury by way of inflammation, demyelination, endothelial invasion, and hypoxia. Regardless of the mechanism of entry and damage, the subsequent neurologic manifestations profoundly impact patients.

Epilepsy in Covid

Epilepsy in Covid usually happens secondary to:

• Encephalitis (Inflammation of the Brain ),
• Encephalopathy (Toxic substances in the milieu of the Brain or lack of oxygen,salt etc),
• Drug induced by medications used in treatment of Covid
• Missing out medication in those with previous history of Epilepsy and on drugs
• Reactivation of epileptic focus in the brain by Covid virus infection
• Secondary to stroke caused by Covid infection

Special precautions
Those on antiepileptic drugs must continue their anti-epileptic medications. It’s a usual practice to initiate anti-epileptic medications  prophylactically in those who are vulnerable like patients with Encephalitis. Airway protection is a must to avoid choking.

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