title: Surgical treatment of occipital lobe epilepsy.
abstract: OBJECTIVE
  Occipital lobe epilepsy (OLE) accounts for a small percentage of extratemporal epilepsies and only few and mostly small patient series have been reported. Preoperative findings, surgical strategies, histopathological bases, and postoperative outcomes for OLE remain to be elucidated.
  
  
  METHODS
  A group of 54 patients with occipital lobe involvement were identified from a prospective epilepsy surgery database established in 1989. Medical charts, surgical reports, MR imaging, and histopathology data were reviewed, and patients with additional temporal and/or parietal involvement were categorized separately. Seizure outcome was classified according to the Engel classification scheme (Classes I-IV). Two patients were excluded due to incomplete data sets. Fifty-two patients with intractable epilepsy involving predominantly the occipital lobe were included in the study, comprising 17.8% of 292 patients undergoing operations for extratemporal epilepsies.
  
  
  RESULTS
  In nearly all cases (50 [96.2%] of 52), a structural lesion was visible on preoperative MR imaging. Of these cases, 29 (55.8%) had "pure" OLE with no temporal or parietal lobe involvement. Most patients (83%) had complex partial seizures, and 60% also had generalized seizures. All patients underwent occipital lesionectomies or topectomies; 9 patients (17.3%) underwent additional multiple subpial transections. Histopathology results revealed 9 cortical dysplasias (17.3%), 9 gangliogliomas (17.3%), 6 other tumors (11.5%), 13 vascular malformations (25%), and 15 glial scars (28.8%). Visual field deficits were present in 36.4% of patients preoperatively, and 42.4% had new or aggravated visual field deficits after surgery. After a mean follow-up of 80 months, 36 patients were seizure free (69.2% Engel Class I), 4 rarely had seizures (7.7% Engel Class II), 8 improved more than 75% (15.4% Engel Class III), and 4 had no significant improvement (7.7% Engel Class IV). Multifactorial logistic regression analysis revealed that early age at epilepsy manifestation (p = 0.031) and shorter epilepsy duration (p = 0.004) were predictive of better seizure control. All other clinical and surgical factors were not significant in predicting outcome.
  
  
  CONCLUSIONS
  Occipital lobe epilepsy is an infrequent but significant cause of extratemporal epilepsy. Satisfactory results (Engel Class I or II) were obtained in 77% of patients in our series. Postoperative visual field deficits occurred in a significant proportion of patients. In the modern MR imaging era, lesions should be investigated in patients with OLE and lesionectomies should be performed early for a better outcome.
authors.affiliation: Department of Neurological Surgery, University of California, Irvine, Orange, California 92868-3298, USA. dbinder@uci.edu
authors.forename: Devin K
authors.initials: DK
authors.lastname: Binder
authors.forename: Marec
authors.initials: M
authors.lastname: Von Lehe
authors.forename: Thomas
authors.initials: T
authors.lastname: Kral
authors.forename: Christian G
authors.initials: CG
authors.lastname: Bien
authors.forename: Horst
authors.initials: H
authors.lastname: Urbach
authors.forename: Johannes
authors.initials: J
authors.lastname: Schramm
authors.forename: Hans
authors.initials: H
authors.lastname: Clusmann
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D016208:Databases, Factual; D018572:Disease-Free Survival; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome