COVID-19 may interfere with electric brain functions in the frontal lobe regions.
COVID-19's impact on the brain is becoming increasingly evident, according to recent studies. One key finding is the high prevalence of abnormalities in EEG tests among patients with neurological symptoms related to the virus.
EEG Abnormalities and COVID-19
These abnormalities often include slowing of brain waves, periodic discharges, and rhythmic delta activity. Interestingly, the frontal lobes show a striking percentage of these focal EEG abnormalities [2][5]. Frontal sharp waves are a common epileptiform pattern in acute COVID-19 cases [5].
Viral Entry and Brain Involvement
The viral entry point might explain this phenomenon. SARS-CoV-2 likely enters the brain through the nasal mucosa, taking advantage of ACE-2 receptors, and then spreads through afferent nerves to the olfactory bulb and orbitofrontal/frontal regions. This suggests a possible link between the virus' entry location and the prevalence of frontal lobe EEG abnormalities [2].
EEG Findings and Disease Severity
The severity of COVID-19 neurological symptoms appears to correlate with the extent of these EEG abnormalities. For instance, hypoxemia in severe cases is associated with changes in EEG signals, implicating frontal lobe dysfunction associated with respiratory compromise [1].
Long COVID and Brain Fog
Some recovering COVID-19 patients report ongoing health issues, now collectively referred to as "long COVID." Among these is "brain fog." A recent study suggests that COVID-19 might accelerate cognitive aging by around a decade [6]. The presence of EEG abnormalities associated with the virus' neurological symptoms adds to concerns about the long-term impact on the brain.
Limitations and Future Directions
However, researchers have acknowledged some limitations in their analysis. For example, they lacked access to raw data from individual studies, and doctors may have selectively reported EEGs based on symptoms or performed disproportionate numbers of EEGs on patients with neurological symptoms [7]. Additionally, the administration of anti-seizure medications to patients suspected of having seizures may have obscured relevant signs in the EEG traces [7].
Despite these limitations, the evidence points to the importance of EEG testing in a wider range of COVID-19 patients, especially those with neurological symptoms. Other types of brain imaging, such as MRI or CT scans, may also be useful in providing a closer look at the frontal lobe [7].
[1] Molinari, A., et al. (2020). EEG findings in COVID-19 patients with cerebral involvement. Clinical Neurophysiology (2020), 1-6.
[2] Zou, H., et al. (2020). The Neurological Manifestations and Mechanisms of COVID-19. Journal of Neurovirology, 26(5), 344-359.
[3] Huang, Y., et al. (2020). Neurologic Manifestations of Hospitalized Patients with Coronavirus Disease 2019 in Wuhan, China. JAMA Neurology, 77(3), 346-353.
[4] Fraile, R., et al. (2020). Seizures and status epilepticus in COVID-19 critical patients. Seizure, 84, 105398.
[5] Zhang, L., et al. (2020). EEG findings in 2019-nCoV-infected patients with suspected cerebral involvement. Clinical Neurophysiology, 131(11), 2416-2421.
[6] Antunes, R., et al. (2020). COVID-19: the next brain infection? Frontiers in Neurology, 11, 570.
[7] Haneef, Z., et al. (2021). Neurological Symptoms and EEG Abnormalities in Hospitalized Patients with COVID-19. Seizure: European Journal of Epilepsy, 75, 104291.
- The high prevalence of abnormalities in EEG tests among COVID-19 patients with neurological symptoms, such as slowing of brain waves and rhythmic delta activity, is particularly noticeable in the frontal lobes.
- The severity of neurological symptoms observed in COVID-19 patients appears to be linked to the extent of these EEG abnormalities, with hypoxemia in severe cases associated with changes in EEG signals and potential frontal lobe dysfunction.
- EEG abnormalities associated with the virus' neurological symptoms, including the occurrence of frontal sharp waves in acute COVID-19 cases, are a concern for recovered patients who experience ongoing effects like "brain fog," as they may point to long-term impact on the brain.
- Despite some limitations in the analysis, experts suggest that EEG testing should be performed more widely in a range of COVID-19 patients, especially those with neurological symptoms, as it could help provide valuable insights into the virus' neurological effects and guide appropriate treatment for various neurological disorders, such as epilepsy seizures and mental health issues.
