Abstract
Patients 60 years or older are one of the highest risk age groups for development of epilepsy. Clinical and neuroimaging analysis has typically accounted for etiology in two-thirds of these patients, while the data on histopathology are lacking. We provide the first analysis of the histopathological substrates underlying drug-resistant epilepsy (DRE) in older adults/elderly patients who underwent resective epilepsy surgery (RES) at Cleveland Clinic. A total of 78 patients (mean age ± standard deviation: 64.7 ± 3.7 years; 59% female) were included in the study. The most common pathologies included hippocampal sclerosis (HS; 35.9%; all visible on magnetic resonance imaging [MRI]), focal cortical dysplasia (FCD; 25.6%) and remote infarct/ischemic changes (12.8%). Underlying pathology did not differ significantly between the patients achieving a good seizure outcome (Engel class I; 77% [47 of 61 patients]) and the rest of the cohort. With one exception, all MRI-negative cases had FCD type Ib. A receiver-operating characteristic (ROC) curve analysis found a significant association (P = 0.002) between seizure-onset age and HS, whereby the odds of its presence were reduced by 4% for every 1 year increase in the age at seizure onset. The model showed that the age cutoff for seizure onset predicting HS was 43 years, with a negative predictive value of 81.6%. None of the 14 patients with late-onset epilepsy (≥60 years of age) were found to have HS; they mostly had acquired lesions. Our study provides histopathologic evidence for the diminished role of late-onset HS in DRE in older adults/elderly who undergo RES.