title: Presurgical entorhinal cortex volume and postoperative seizure outcome in temporal lobe epilepsy.
abstract: BACKGROUND
  Although temporal lobe surgery is an effective treatment for patients with intractable mesial temporal lobe epilepsy (mTLE), a third of patients will continue to experience seizures at 2 years after surgery. The reasons are unknown. One suggestion is that patients with abnormalities of the entorhinal cortex might have a subtype of mTLE that is resistant to surgery. We investigated the association between presurgical entorhinal cortex volume and postoperative outcome in patients with mTLE.
  
  
  METHODS
  78 patients with intractable mTLE and unilateral hippocampal sclerosis underwent comprehensive presurgical evaluation at the Department of Epileptology, University Hospital Bonn, Germany. Patients and 76 age-matched healthy controls received an MP-RAGE T1-weighted MRI. We determined left and right entorhinal cortex volume, masked to participant identity, using rigorous manual techniques. All patients had complex partial seizures, underwent amygdalohippocampectomy, and received postoperative outcome assessment.
  
  
  RESULTS
  There was a significant effect of group (controls, left mTLE, right mTLE) on the volume of the left (univariate ANOVA F=29·6, p<0·001) and right (F=8·3, p<0·001) entorhinal cortex, and entorhinal asymmetry (F=92·6, p<0·001). Post-hoc analysis with Bonferroni correction revealed that patients with left (p<0·001) and right (p=0·01) mTLE had significantly reduced volume of the ipsilateral entorhinal cortex relative to controls, and patients with right mTLE also had volume reduction of the contralateral entorhinal cortex (p=0·01). We found no significant differences in entorhinal cortex volumes and clinical data between patients (n=48, 62%) surgically rendered seizure free (ILAE I-II) and patients (n=30, 38%) with persistent seizures (ILAE III-VI).
  
  
  CONCLUSIONS
  These data indicate that gross atrophy of the entorhinal cortex is not a predictor of postoperative outcome in patients with intractable mTLE. We are evaluating whether alterations in entorhinal cortex connectivity and extent of resection are related to postoperative outcome in our series of patients.
  
  
  BACKGROUND
  This work was supported by a UK Medical Research Council grant awarded to SSK.
authors: Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK. Electronic address: S.Elkommos@liverpool.ac.uk.
authors: Samia
authors: S
authors: Elkommos
authors: Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, London, UK.
authors: Mark P
authors: MP
authors: Richardson
authors: Department of Epileptology, University of Bonn, Bonn, Germany; Department of Neurocognition/Imaging, Life & Brain Research Centre, Bonn, Germany.
authors: Jan-Christoph
authors: JC
authors: Schoene-Bake
authors: Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
authors: Anthony
authors: A
authors: Marson
authors: Department of Epileptology, University of Bonn, Bonn, Germany; Department of Neurocognition/Imaging, Life & Brain Research Centre, Bonn, Germany.
authors: Christian
authors: C
authors: Elger
authors: Department of Epileptology, University of Bonn, Bonn, Germany; Department of Neurocognition/Imaging, Life & Brain Research Centre, Bonn, Germany.
authors: Bernd
authors: B
authors: Weber
authors: Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK; Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, London, UK.
authors: Simon S
authors: SS
authors: Keller