The effect of cortical and subcortical parcel volumes on postictal generalized EEG suppression

Alterations to brain structures and networks involved in central autonomic and respiratory control are possible biomarkers of SUDEP, but were mainly demonstrated in people at high risk. Postictal generalized EEG suppression (PGES) has been recorded in every case of near or confirmed SUDEP. The structural alterations underpinning PGES are not known.

This retrospective study included the brain MRIs of 100 patients with focal and generalized epilepsy who had experienced at least one generalized tonic-clonic seizure (GTCS) documented through long-term video-EEG monitoring, with PGES defined as postictal EEG activity below 10 microvolts lasting at least 20 s. Brain MRIs were parcellated into cortical and subcortical volumes, with further parcellation of thalamic subfields, and univariate and multivariate logistic regression models were applied to identify brain regions associated with PGES.

PGES was observed in 52 of 100 patients. Patients with PGES were older and had a slower heart rate before and after seizures compared to those without PGES. The tonic phase of GTCS was longer in patients with PGES. Univariate logistic regression analysis identified significant associations between PGES and six brain regions: the left and right lateral occipital cortices, left and right precuneus, and left and right thalamus. Multivariate analysis revealed that the right thalamus and both precuneus were independent predictors of PGES. Further analysis of thalamic subfields showed an increased volume of the ventral anterior nucleus of the right thalamus in patients with PGES.

Structural alterations in the right thalamus and precuneus are significantly associated with the presence of PGES in epilepsy patients.

Some people with epilepsy show a period of very low brain activity after a seizure, called PGES, which may be linked to a higher risk of sudden death. We analyzed brain scans from 100 people with epilepsy and found that two brain regions-the right thalamus and the precuneus-were different in those with PGES. These findings may help doctors understand which patients are more at risk after seizures and how to better protect them.