Reduced Neocortical Thickness and Complexity Mapped in Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

We mapped the profile of neocortical thickness and complexity in patients with mesial temporal lobe epilepsy (MTLE) and hippocam-pal sclerosis. Thirty preoperative high-resolution magnetic reso-nance imaging scans were acquired from 15 right (mean age: 31.96 9.7 standard deviation [SD] years) and 15 left (mean age: 30.8 6 8.4 SD years) MTLE patients who were seizure-free for 2 years after anteriomesial temporal resection. Nineteen healthy controls were also scanned (mean age: 24.86 3.9 SD years). A cortical pat-tern matching technique mapped thickness across the entire neocor-tex. Mesial temporal structures were not included in this analysis. Cortical models were remeshed in frequency space to compute their fractal dimension (surface complexity). Both MTLE groups showed up to 30 % bilateral decrease in cortical thickness, in the frontal poles, frontal operculum, orbitofrontal, lateral temporal, and occipital regions. In both groups, cortical complexity was decreased in multiple lobar regions. Significant linkages were found relating longer duration of epilepsy to greater cortical thickness reduction in the superior frontal and parahippocampal gyrus ipsilateral to the side of seizure onset. The pervasive extrahippocampal structural deficits may result from chronic seizure propagation or may reflect other causes such as initial precipitating factors leading to MTLE