Abstracts

Pathological and imaging studies suggest that structural abnormalities in malformations of cortical development (MCD) extend beyond the obvious lesion. Previous studies have been limited to the evaluation of the hippocampus, which has been found to be atrophic in up to 20% of MCD patients, mostly those with heterotopia. Our purpose was to examine the occurrence atrophy in various limbic structures in MCD. Hippocampus (Hip), amygdala (A), and entorhinal cortex (EC) were segmented on high-resolution MRI (isotropic voxels of 1 mm3) in 71 adult patients including 31 with focal cortical dysplasia (FCD), 20 with heterotopia (HET), and 20 with polymicrogyria (PMG). Patients were compared to 48 sex- and age-matched controls. All patients had video-EEG telemetry. Based on normal controls[apos] cutoff of -2 SD, at least one structure was atrophic in 49/71 (70%) of MCD patients. The proportion of mesial atrophy was not different among the various MCD types. The EC was the only atrophic structure in 29% (14/49), the Hip in 16% (8/49), and the AM in 8% (4/49). The most frequent combination was atrophy of Hip and EC (27%=13/48 patients). All three structures were atrophic in 6% (3/48) of MCD patients. Mesial temporal atrophy was equally found in patients with temporal and those with extra-temporal epileptic foci (58% vs. 76%, p=0.2). We found no association between side of mesial temporal atrophy and side of the MCD lesion. Mesial temporal atrophy is found in a large proportion of MCD patients, regardless of the type and side of malformation. Contrary to temporal lobe epilepsy, the presence of mesial atrophy in MCD is unrelated to the epileptic focus. Our results suggest that MCD are indeed associated with widespread structural brain damage. (Supported by Canadian Institutes of Health Research (Grant # 203707).)