Abstracts

Rationale: Mesial temporal lobe epilepsy (MTLE) constitutes an important entity since it is the most frequent type of partial epilepsy. 10% to 40% of patients achieve control, depending of the drug-response concept utilized. Hippocampal sclerosis has been related to pharmacoresistance in MTLE. Studies with voxel-based morphometry (VBM) have shown that the atrophy goes beyond the hippocampus and involves also other brain regions ipsilateral and contralateral to the side of seizure onset. On the other hand, studies comparing responders with non-responders are lacking. The objective of the present study was to compare structural changes with VBM between MTLE patients with different patterns of response to antiepileptic drugs (AEDs). Methods: 85 subjects with MTLE were enrolled and divided into 23 AED responders, seizure free for at least one year (66.2% women; mean age 45.4 +or- 11.1), 30 pharmacoresistants undergoing clinical treatment (57.8% women, mean age 43.3+or-9.2) and 33 submitted to surgical treatment (44,1% women, mean age 36.4+or-9.8). All subjects underwent MR scanning on a 2T scanner (Elscint Prestige,Haifa, Israel). VBM gray matter volume comparisons were made between non-pharmacoresistants, clinical pharmacoresistants, surgical pharmacoresistants and healthy controls Results: Compared to controls, all groups showed a more intense correlation between hippocampal gray matter volume and regional gray matter volume in locations such as the contralateral hippocampus, bilateral parahippocampal gyri and frontal and parietal areas. When this comparison was made between AED responders and clinical pharmacoresistants there were few areas with different gray matter concentrations (ipsilateral parietal and contralateral frontal opercular regions). However, when comparing AED responders and pre-operative MRIs of patients who underwent surgical treatment, there were more differences contralateral to the main focus, such as calcarine (p<0.05), cingulum (p<0.05), inferior frontal (p<0.05), and temporal pole regions (p<0.01). We also noted atrophy in the ipsilateral pallidum (p<0.02) and a tendency of smaller ipsilateral amygdala, although not statiscally significant (p>0.05)figure 1 Conclusions: Our data indicate that subjects who experience the poorest seizure control (surgical candidates) present more widespread gray matter atrophy, involving contralateral areas when compared to AED responders