title: Entorhinal cortex MRI assessment in temporal, extratemporal, and idiopathic generalized epilepsy.
abstract: OBJECTIVE
  We previously showed a reduction in the volume of the entorhinal cortex (EC) ipsilateral to the seizure focus in patients with intractable temporal lobe epilepsy (TLE). The purpose of this study was to examine the specificity of EC atrophy in epilepsy.
  
  
  METHODS
  We performed volumetric measurement of the EC on high-resolution magnetic resonance imaging (MRI) in patients with TLE (n = 70), extratemporal lobe epilepsy (ETE; n = 18), and idiopathic generalized epilepsy (IGE; n = 20). EC volumes of epilepsy patients were compared with those of 48 age- and sex-matched normal controls. Within the TLE group, 63 patients were selected prospectively with hippocampal atrophy ipsilateral to the seizure focus. The remaining seven patients were chosen retrospectively based on normal volumetric MRI of the hippocampus and amygdale, as well as normal histopathologic examination of the resected tissue.
  
  
  RESULTS
  Compared with normal controls, EC volume was smaller ipsilateral but not contralateral to the seizure focus in patients with TLE (p < 0.001). No difference in the EC volumes ipsilateral and contralateral to the seizure focus was seen in patients with ETE and IGE compared with normal controls. The individual analysis showed that the EC was atrophic in 73% of TLE patients with hippocampal atrophy. Three of the seven TLE patients with normal volumetric MRI of the hippocampus and amygdala and normal histopathologic examination had EC atrophy ipsilateral to the seizure focus. In no patient with ETE or IGE was the EC found to be atrophic.
  
  
  CONCLUSIONS
  EC atrophy ipsilateral to the seizure focus appears to be specific to mesial temporal lobe structural damage associated with TLE.
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada. neda@bic.mni.mcgill.ca
authors.forename: Neda
authors.initials: N
authors.lastname: Bernasconi
authors.forename: Frederick
authors.initials: F
authors.lastname: Andermann
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Arnold
authors.forename: Andrea
authors.initials: A
authors.lastname: Bernasconi
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000473:pathology; D001284:Atrophy; D018728:Entorhinal Cortex / Q000473:pathology*; D004828:Epilepsies, Partial / Q000175:diagnosis* / Q000473:pathology; D004829:Epilepsy, Generalized / Q000175:diagnosis* / Q000473:pathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D012189:Retrospective Studies