After retrospectively analyzing data from more than 300,000 people, researchers recently Neurology magazine paper report that a diagnosis of coronavirus disease 2019 (COVID-19) was associated with a greater risk of both seizures and epilepsy compared to those diagnosed with influenza infection.
Stady: Incidence of epilepsy and seizures during the first six months after diagnosis of COVID-19: a retrospective study. Image credit: Chaikom/Shutterstock.com
Neurological symptoms of COVID-19
To date, COVID-19, caused by SARS-CoV-2, caused by severe acute respiratory syndrome (SARS-CoV-2), has claimed more than 6.6 million lives. In addition to a high fatality rate, COVID-19 is also associated with significant morbidity, especially among patients with severe symptoms who are hospitalized for this infection.
In fact, many people hospitalized with COVID-19 have reported neurological symptoms, the most common of which include muscle aches, headaches, dizziness, confusion, and altered taste and smell. In some severe cases, COVID-19 has also been associated with seizures and strokes. However, these events are rare, with a seizure rate of about 1%.
How does COVID-19 affect the nervous system?
Although researchers previously believed that SARS-CoV-2 was able to pass through the blood-brain barrier (BBB) to directly cause damage to the central nervous system (CNS), cerebrospinal fluid (CSF) samples of COVID-19 patients with Neurological symptoms They fail to show the presence of viral genetic material.
A growing body of evidence suggests that immune activation and subsequent inflammation by the central nervous system are likely responsible for the neuroprotective effects of COVID-19. More specifically, CSF samples obtained from severe COVID-19 patients were positive for interferon-regulating genes in dendritic cells, activated T cells, and natural killer (NK) cells, as well as increased levels of both interleukin-1 (IL-1) and IL-12 compared to blood plasma levels.
Autopsy studies of patients who died of severe COVID-19 also reported accumulation of macrophages and CD8+ T cells in perivascular areas, as well as widespread microglial activation. These results indicate that although SARS-CoV-2 is not present within the central nervous system, the diffuse inflammatory response and Cellular storm induced by COVID-19 likely regulates the trafficking of these inflammatory molecules into the central nervous system.
Increased risk of seizures compared to patients with influenza
In the current study, the researchers analyzed the electronic records of more than 300,000 patients, with both the COVID-19 and influenza group consisting of 152,754 patients each. No patient with a history of epilepsy or recurrent seizures was included in the study.
The six-month incidence of seizures or epilepsy was greater in the COVID-19 cohort than in the influenza cohort at 0.94% and 0.60%, respectively. When considered separately, the risk of seizures due to COVID-19 and influenza was 0.81% and 0.51%, respectively, while the risk of epilepsy was 0.30% and 0.17%, respectively.
When considering age, COVID-19 was found to similarly increase the risk of seizures in both children and adults compared to influenza infection. More specifically, children diagnosed with COVID-19 had a 1.34% risk of developing seizures or epilepsy compared to 0.69% when diagnosed with the flu. Conversely, adults had a 0.84% and 0.54% risk of seizures and epilepsy when diagnosed with COVID-19 or influenza, respectively.
Although patients hospitalized with COVID-19 are generally at increased risk of neurological symptoms, the current study reported that non-hospitalized COVID-19 patients were more likely to have seizures or epilepsy than hospitalized patients.
The risk of developing seizures or epilepsy due to COVID-19 and influenza infection was approximately 23 days. In adults, this peak risk was 21 days post infection, while in children the risk was greatest at 50 days post infection. In fact, 50 days after infection, children diagnosed with COVID-19 were three times more likely to develop seizures or epilepsy than at the same time point after contracting the flu.
Despite most mask requirements and social distancing measures being relaxed, SAR-CoV-2 continues to mutate and spread around the world, indicating that COVID-19 remains a significant public health risk. The current study found that COVID-19 was associated with a greater risk of seizures than influenza, with children particularly vulnerable to this neuroprotective effect.
More studies are needed to evaluate the long-term outcomes for COVID-19 patients who experience seizures.
- Tackett, M, Devinsky, OR. Cross, H. et al. (2022). Incidence of epilepsy and seizures during the first six months after diagnosis of COVID-19: a retrospective study. Neurology. doi: 10.1212/WNL.0000000000201595.