title: Subclinical abnormal gyration pattern, a potential anatomic marker of epileptogenic zone in patients with magnetic resonance imaging-negative frontal lobe epilepsy.
abstract: BACKGROUND
  Epilepsy surgery for magnetic resonance imaging (MRI)-negative patients has a less favorable outcome.
  
  
  OBJECTIVE
  Detection of subclinical abnormal gyration (SAG) patterns and their potential contribution to assessment of the topography of the epileptogenic zone (EZ) is addressed in MRI-negative patients with frontal lobe epilepsy.
  
  
  METHODS
  Between September 1998 and July 2005, 12 MRI-negative frontal lobe epilepsy patients underwent stereoelectroencephalography with postcorticectomy follow-up of longer than 1 year (average, 3.3 years). Original software (BrainVISA/Anatomist, http://brainvisa.info) trained on a database of normal volunteers was used to determine which sulci had morphology out of the normal range (SAG). Topography of the EZ, SAG pattern, corticectomy, postoperative seizure control, and histopathology were analyzed.
  
  
  RESULTS
  At last follow-up, 8 of 12 patients (66.7%) were Engel class I (7 IA and 1 IB), 2 class II, and 2 class IV. Small focal cortical dysplasia was histologically diagnosed in 9 of the 12 patients (75%), including 7 of 8 seizure-free patients (87.5%). A SAG pattern was found to be in the EZ area in 9 patients (75%), in the ipsilateral frontal lobe out of the EZ in 2, and limited to the contralateral hemisphere in 1.
  
  
  CONCLUSIONS
  SAG patterns appear to be associated with the topography of the EZ in MRI-negative frontal lobe epilepsy and may have a useful role in preoperative assessment. Small focal cortical dysplasia not detected with MRI is often found on histopathological examination, particularly in the depth of the posterior part of the superior frontal sulcus and intermediate frontal sulcus, suggesting a specific developmental critical zone in these locations.
authors.affiliation: Service de Neurochirurgie Fonctionnelle et Stéréotaxique, CHU Timone, Assistance Publique des Hôpitaux de Marseille, Marseille, France. jregis@ap-hm.fr
authors.forename: Jean
authors.initials: J
authors.lastname: Régis
authors.forename: Manabu
authors.initials: M
authors.lastname: Tamura
authors.forename: Michael C
authors.initials: MC
authors.lastname: Park
authors.forename: Aileen
authors.initials: A
authors.lastname: McGonigal
authors.forename: Denis
authors.initials: D
authors.lastname: Rivière
authors.forename: Olivier
authors.initials: O
authors.lastname: Coulon
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bartolomei
authors.forename: Nadine
authors.initials: N
authors.lastname: Girard
authors.forename: Dominique
authors.initials: D
authors.lastname: Figarella-Branger
authors.forename: Patrick
authors.initials: P
authors.lastname: Chauvel
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mangin
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002648:Child; D004569:Electroencephalography; D017034:Epilepsy, Frontal Lobe / Q000145:classification / Q000150:complications / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D054220:Malformations of Cortical Development / Q000209:etiology / Q000473:pathology*; D008875:Middle Aged; D009493:Neurosurgery / Q000379:methods; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D055815:Young Adult