2026 American Academy of Neurology Abstract Website

Objective:

This study aimed to evaluate the clinical and neuroimaging correlates of obstructive sleep apnea (OSA) in adults with late-onset unexplained epilepsy (LOUE).

Background:

The recurrent apnea/hypopnea cycles in OSA drive inflammation and endothelial dysfunction which may contribute to seizure exacerbation in LOUE. Thus, identifying and treating OSA may improve outcomes for adults with LOUE.

Design/Methods:

We prospectively recruited adults with LOUE (unexplained seizure after age 55) who underwent polysomnography or home sleep testing as part of their clinical care. Participants were dichotomized into no/mild OSA (apnea-hypopnea index [AHI]<15) and moderate/severe OSA (AHI≥15) groups. We evaluated their plasma phospho-tau-217 (ptau-217) levels and extracted seizure semiology variables, SSRI/SNRI use, and number of anti-seizure medications (ASMs). Participants also underwent magnetic resonance imaging (MRI), and we quantified their hippocampal and amygdala volumes using FreeSurfer.

Results:

Of the 85 enrolled participants, 31 underwent sleep testing, and 2 were excluded due to a prior diagnosis and treatment of OSA. The final cohort (n=29) had a mean age of 69.89±6.66 years and was 45% female. 15 participants (51.7%) had no/mild OSA and 14 (48.3%) had moderate/severe OSA. The mean time between sleep study and MRI was 1.5 years. After controlling for age and sex, participants with moderate/severe OSA were more likely to be on an SSRI/SNRI (OR=65.93, p=0.020), less likely to present with a nocturnal generalized tonic-clonic seizure (GTCS, OR=0.082, p=0.038), and had lower total amygdala volumes (β=-0.00027, p=0.049) relative to those with no/mild OSA. There were no significant differences in ptau-217 levels (p=0.89) or ASM number (p=0.45) between the two groups.

Conclusions:

Moderate/severe OSA is common in LOUE and is associated with greater SSRI/SNRI use and amygdala atrophy, which could reflect underlying dysfunction in the limbic system. Older adults with LOUE and moderate/severe OSA are also less likely to present with a nocturnal GTCS.