Abstracts

We investigated longitudinal changes in the volumes and shapes of the hippocampi of non-surgical and post-surgical patients with unilateral mesial temporal lobe epilepsy., Sixteen non-surgical patients had a repeat brain MRI with a mean interval of 3.7 years and 16 post-surgical patients had two postoperative MRI scans with a mean interval of 4.8 years. We measured ipsilateral and contralateral hippocampal volumes (IHV and CHV) in the non-surgical group and CHV in the postsurgical group. Hippocampal shape deformity analysis (HSDA) was also performed in each group., In non-surgical patients, both IHV and CHV decreased significantly between the two scans (7.3[plusmn]5.7%, p[lt]0.001 and 2.5[plusmn]2.6%, p=0.002). Moreover, IHV percent decreases were significantly correlated with the number of total seizures between the two scans (r=0.57, p=0.02). HSDA also showed inward deformities in both ipsilateral and contralateral hippocampi in non-surgical patients (uncorrected p[lt]0.05). In post-surgical patients, mean CHV (2481.1[plusmn]364.9mm³) for first postsurgical scans was not significantly different from mean CHV (2480.4[plusmn]316.1mm³) for second scans. Total seizure numbers during the year before surgery were negatively correlated with CHV losses between the two postsurgical scans (r=-0.72, p=0.002). HSDA of contralateral hippocampi between the two postsurgical scans mainly showed outward deformities in head, body and tail but small inward deformities in tail., These results suggest that recurrent seizures induce progressive atrophy in both ipsilateral and contralateral hippocampi, but that a seizure-free state after the resection of an epileptic focus prevents longitudinal volume loss of the contralateral hippocampus and may facilitate a partial volume increase.,