Abstracts

Rationale: : Diffusion tensor imaging (DTI) provides information about neural tissue microstructure, specifically, white matter (WM). In experimental studies, repeated seizures produce neuronal damage and cell death. In addition, axonal demyelination, edema, replacement of axons by glial cells, and astrocyte proliferation, may all be associated with seizure induced damage. DTI studies are sensitive to detection WM damage in various disease states. DTI can disclose WM abnormalities in apparently normal regions by conventional imaging, uncovering microscopic pathological changes. Our objective in this study is to evaluate corpus callosum (CC) fiber integrity in patients with medically refractory epilepsy secondary to hippocampal sclerosis (HS), measuring fractional anisotropy (FA) and apparent diffusion coefficients (ADC). Methods: Eight HS patients and six healthy controls were studied. Magnetic resonance imaging was performed in a 3.0 T scanner (Achieva Intera, PHILIPS). Region of interest (ROI) analysis was performed in DTI sequences to access FA and ADC measurements. Mean values and standard deviations (SD) were calculated. Results: Mean FA in the CC was significant reduced in HS patients (0.567; SD: 0.027) compared to healthy controls (0.609; SD: 0.030) (p=0.018). Mean ADC in patients was significant higher (0.876 x 10-3 mm2/s; SD: 0.038 x 10-3 mm2/s) than in controls (0.802 x 10-3 mm2/s; SD: 0.047 x 10-3 mm2/s)(p=0.007). Conclusions: Those data demonstrate abnormalities in the integrity of the connecting white matter tracts (specifically, CC) in patients with HS associated epilepsy. WM involvement appears to be another at-distance effect of HS. The extent of WM tract abnormalities and its impact on cognitive function and drug refractoriness should be further elucidated.