Bilateral cingulum fiber reductions in temporal lobe epilepsy with unilateral hippocampal sclerosis

Abstract

PurposeTo evaluate whether white matter tracts within the Papez circuit are altered in patients with unilateral hippocampal sclerosis (HS). MethodsTwenty patients with histologically proven unilateral HS and 20 age-matched controls were studied with a 3T Epilepsy-dedicated MRI protocol including a MPRAGE sequence for hippocampus volumetry and a diffusion tensor imaging (DTI) sequence (61 diffusion-encoding directions, 2×2×2mm3 voxels) for diffusion tensor tractography (DTT). An energy-based global tracking algorithm was used to calculate streamline counts (SC) and fractional anisotropy (FA) of cingulate, fornix, and mammillo-thalamic tracts, respectively. ResultsSclerotic hippocampi were significantly smaller compared to the contralateral side and to age-matched controls. Cingulum SC but not FA were reduced on the hippocampal sclerosis (258+81.0) and contralateral side (271+85.6) compared to age-matched controls (447+138). ConclusionFocusing on white matter tracts of the Papez circuit we showed that in patients with intractable temporal lobe epilepsy unilateral hippocampal sclerosis is associated with a bilateral reduction of cingulum association fibers projecting from the cingulate gyrus to the parahippocampal gyrus.