title: Surgical outcomes in patients with extratemporal epilepsy and subtle or normal magnetic resonance imaging findings.
abstract: BACKGROUND
  Surgery is an important therapeutic option in patients with medically refractory epilepsy. The combination of an extratemporal epileptic focus and nonlesional magnetic resonance imaging (MRI) was often believed to portend a poor outcome.
  
  
  OBJECTIVE
  To investigate the outcome and analyze potential prognostic predictors in patients without lesions on MRI who underwent extratemporal resections.
  
  
  METHODS
  Clinical, presurgical evaluation, invasive monitoring, and postoperative data of patients with high-resolution MRI that was initially reported as nonlesional were reviewed. Patients were reclassified as MRI-positive if an MRI abnormality related to the epilepsy was revealed at the multidisciplinary presurgical patient management conference, or as MRI-negative if imaging remained normal or revealed incidental findings.
  
  
  RESULTS
  Sixty patients were identified; 72% were MRI-negative. In the original cohort, the median seizure-free duration was 1.32 years (95% confidence interval [CI], 0.16-2.0); probability of seizure freedom at 2 years was 36% (95% CI, 30%-43%). In the MRI-negative group, the median seizure-free duration was 1.52 years (95% CI, 0.12-5.17); probability of seizure freedom at 2 years was 42% (95% CI, 33%-50%). Complete resection of ictal onset areas and absence of acute postoperative seizures were significantly associated with longer seizure freedom (risk ratio 4.9, P = .004; 95% CI, 1.6-16.7 and 22.1, P < .001; 95% CI, 5.9-94.7, respectively).
  
  
  CONCLUSIONS
  Among patients with medically refractory MRI nonlesional extratemporal epilepsy, detailed evaluation and subsequent resection leads to seizure freedom in 42% of patients at 2 years.
authors.affiliation: Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
authors.forename: Siew-Ju
authors.initials: SJ
authors.lastname: See
authors.forename: Lara E
authors.initials: LE
authors.lastname: Jehi
authors.forename: Sumeet
authors.initials: S
authors.lastname: Vadera
authors.forename: Juan
authors.initials: J
authors.lastname: Bulacio
authors.forename: Imad
authors.initials: I
authors.lastname: Najm
authors.forename: William
authors.initials: W
authors.lastname: Bingaman
mesh_terms: D018572:Disease-Free Survival; D004827:Epilepsy / Q000175:diagnosis* / Q000453:epidemiology / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D019635:Neurosurgical Procedures / Q000706:statistics & numerical data*; D009820:Ohio / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology*; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult