Hippocampal size anomalies in a community-based cohort with childhood-onset epilepsy

Abstract

OBJECTIVES:: Epidemiologic evidence suggests the natural history of refractory mesial temporal lobe epilepsy is complicated, yet little is known about the hippocampus from the nontertiary center perspective. Methods: In a community-based cohort, individuals with nonsyndromic focal epilepsy with onset <16 years and controls had research MRI scans. Hippocampal (HC) volumes were manually measured, corrected for total brain volume, and converted to Z scores (ZHC) based on the controls'values. Volumes in cases and controls were compared. Results: Average volumes were not significantly different in cases with unknown cause (n = 117) relative to controls (n = 63). The group with structural and other conditions (n = 23) had significantly smaller volumes. Asymmetry (larger/smaller HC) did not vary among the 3 groups. Hippocampal variances were significantly larger in each epilepsy group relative to controls. In the unknown cause group, 25 (21%) had extreme values: 15 (13%) with ZHC >1.96; 10 (9%) with ZHC