Entorhinal cortex atrophy in epilepsy patients exhibiting normal hippocampal volumes

Objective: To determine whether MRI volumetric measurement of the entorhina l cortex could detect structural damage and lateralize the seizure focus in patients with temporal lobe epilepsy in whom no measurable hippocampal abn ormalities were found. Background: A reduction in the volume of the entorhi nal cortex ipsilateral to the seizure focus in patients with intractable te mporal lobe epilepsy and hippocampal atrophy was recently shown. Methods: M RI volumetric analysis of the entorhinal cortex was performed using a T1-we ighted three-dimensional gradient echo sequence in 24 control subjects and 22 patients with temporal lobe epilepsy and normal hippocampal volumes. Thi rteen patients underwent surgery, with a mean postoperative follow-up of 36 months. Results: Group analysis (multivariate analysis of variance) showed a reduction in the volume of the entorhinal cortex ipsilateral to the seiz ure focus in patients with left (p < 0.0001) and right temporal lobe epilep sy (p <: 0.0001). Lateralization of the seizure focus could be done in 14 o f 22 patients (64%) based on entorhinal cortex volumetry. Conclusion: Entor hinal cortex atrophy ipsilateral to the seizure focus supports the presence of structural damage in the mesial temporal lobe in patients with temporal lobe epilepsy and normal hippocampal volumes and emphasizes the participat ion of the entorhinal cortex in the pathogenesis of this disorder.