Progressive brain atrophy and cortical reorganization related to surgery in temporal lobe epilepsy

Objective

Epilepsy is associated with progressive cortical atrophy exceeding normal aging. We aimed to explore longitudinal cortical alterations in patients with temporal lobe epilepsy (TLE) and distinct surgery outcomes.

Methods

We obtained longitudinal T1-weighted MRI data in a well-designed cohort, including 53 operative TLE patients, 23 nonoperative TLE patients, and 23 healthy controls. According to seizure outcomes at 24 months after surgery, operative patients were divided into seizure-free (SF) and nonseizure-free (NSF) group. Operative patients were scanned before and after surgery, while nonoperative patients and healthy controls were rescanned with similar interval times. We measured gray matter volume (GMV) in all participants and compared longitudinal cortical alterations among groups.

Results

In nonoperative group, statistically significant GMV decrease was observed in ipsilateral median cingulate and paracingulate gyri and cerebellum crus I when compared with healthy controls. In operative group, postoperative GMV increase was discovered in many regions involving bilateral hemispheres, especially in the frontal lobe, without differences between SF and NSF group. Postoperative GMV decrease was found in ipsilateral inferior frontal gyrus, putamen, thalamus, and insula. GMV decrease in ipsilateral inferior frontal gyrus, putamen, and insula was more significant in SF group.

Interpretation

Progressive cortical atrophy existed in nonoperative TLE patients. Cortical remodeling indicated by postoperative GMV increase may arise mostly from the surgery itself, rather than postsurgical seizure outcomes. More significant GMV decrease in ipsilateral inferior frontal gyrus, putamen, and insula may imply their closer connections with resected regions in seizure-free patients.