Abstracts

Rationale: In epilepsy patients, the corpus callosum (CC) represents a common pathway of seizure propagation. Previous studies have shown changes in the CC in patients with temporal lobe epilepsy (TLE) associated with thinning in posterior callosal regions. The posterior aspect of the CC, known as Witelson regions 6 and 7 (WR6 and WR7) have been shown to connect the temporal lobes. Hypothesis: Selective atrophy of the CC in TLE may be caused by Wallerian degeneration due to neuronal loss in the TL. If so, posterior callosal regions should significantly atrophy after temporal lobectomy. Methods: We identified 50 adult patients who had undergone temporal lobectomy for pharmacoresistant TLE. We performed manual volumetrics on reconstructed 3D high resolution T1 MRI images of posterior CC (WR 6 and 7) and anterior CC as control (WR 2) on the last preoperative and first postoperative MRI (6-12 months after surgery). Region of interest volumes (given in cm3) were calculated for each patient. Data were analyzed using one and two tailed Student’s t-test with statistical significance at p<0.05. Results: 30 patients were women. 31 patients had left temporal lobectomy. WR7 volume decreased by 8.75% (mean preoperative volume =1.7 +/- 0.36, mean postoperative volume =1.55 +/- 0.33, P<0.05) following temporal lobectomy. The adjacent WR6 (0.52 +/-0.15cc) decreased postoperatively by 18.2% (0.42+/-0.13, P<0.05). There was no volumetric change in the rostral WR2 after temporal lobectomy.