title: Persistent seizures following left temporal lobe surgery are associated with posterior and bilateral structural and functional brain abnormalities.
abstract: OBJECTIVE
  To perform a quantitative MRI and retrospective electrophysiological study to investigate whether persistent post-surgical seizures may be due to brain structural and functional abnormalities in temporal lobe cortex beyond the margins of resection and/or bilateral abnormalities in patients with temporal lobe epilepsy (TLE).
  
  
  METHODS
  In 22 patients with left TLE and histopathological evidence of hippocampal sclerosis, we compared pre-surgical brain morphology between patients surgically remedied (Engel's I) and patients with persistent post-surgical seizures (PPS, Engel's II-IV) using voxel-based morphometry (VBM). Routine pre-surgical EEG and invasive and non-invasive telemetry investigations were additionally compared between patient groups.
  
  
  RESULTS
  Results indicated widespread structural and functional abnormalities in patients with PPS relative to surgically remedied patients. In particular, patients with PPS had significantly reduced volume of the ipsilateral posterior medial temporal lobe and contralateral medial temporal lobe relative to surgically remedied patients. Furthermore, successful surgery was associated with clear anterior (89%) and unilateral (100%) temporal lobe EEG abnormalities, whilst PPS were associated with widespread ipsilateral (91%) and bilateral (82%) temporal lobe abnormalities.
  
  
  CONCLUSIONS
  We suggest that these preliminary data support the hypothesis that PPS after temporal lobe surgery are due to functionally connected epileptogenic cortex remaining in the ipsilateral posterior temporal lobe and/or in temporal lobe contralateral to resection.
authors.affiliation: The Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Pembroke Place, Liverpool L69 3BX, UK. s.s.keller@liv.ac.uk <s.s.keller@liv.ac.uk>
authors.forename: Simon S
authors.initials: SS
authors.lastname: Keller
authors.forename: Paul
authors.initials: P
authors.lastname: Cresswell
authors.forename: Christine
authors.initials: C
authors.lastname: Denby
authors.forename: Udo
authors.initials: U
authors.lastname: Wieshmann
authors.forename: Paul
authors.initials: P
authors.lastname: Eldridge
authors.forename: Gus
authors.initials: G
authors.lastname: Baker
authors.forename: Neil
authors.initials: N
authors.lastname: Roberts
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D019635:Neurosurgical Procedures; D012640:Seizures / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D013686:Telemetry; D013702:Temporal Lobe / Q000601:surgery*; D016896:Treatment Outcome