Abstracts

RATIONALE: MRI-based hippocampal atrophy is probably associated with ipsilateral temporal lobe atrophy in patients with intractable temporal lobe epilepsy (TLE). The objective of our study was to compare temporal lobe volumes in patients with TLE due to hippocampal sclerosis (HS)and HS and cortical dysplasia(CD). METHODS: Fifty patients with TLE (right 24, left 26) were studied. Isolated HS was pathologically confirmed in 26 patients and associated with CD in another 20 patients. In four patients no lateral temporal lobe was available for analysis.Data were compared to normative volumes acquired from ten healthy volunteers. RESULTS: Mean age, duration of epilepsy and occurrence of febrile seizures were comparable in both groups. Compared to control volumes , the temporal lobes ipsilateral to the epileptogenic zone were significantly smaller (P<0.01).In left TLE the mean left TL volume was significantly smaller compared to the right (left 66.6+/-8.6cm3 , right 74.9+/-10.0, P<0.001). There was a tendency to a smaller left TL in patients with HS and CD compared to isolated HS (isolated HS 68.2+/-6.2, dual pathology 62.2+/-9.6). In right TLE left and right temporal lobe volumes were comparable and there was no difference between groups. Overall, there were no significant differences between TL volumes ipsilateral to the epileptogenic zone in isolated HS and dual pathology (n=46,isolated HS 70.2+/-6.9;dual pathology 68.3+/-10.3). The contralateral TL's were significantly smaller in the dual pathology group as compared to the isolated HS group (dual 71.2+/-10.7, HS 75.8+/-7.8, P<0.05). CONCLUSIONS: Our results suggest that TLE is commonly associated with atrophy of both mesial and lateral temporal lobe structures . The bilateral decrease in TL volumes in patients with HS associated with CD suggests a possible bilateral more diffuse pathology. Further studies to confirm these data are needed.