title: Seizure outcome after epilepsy surgery in patients with normal preoperative MRI.
abstract: OBJECTIVE
  To determine outcome after epilepsy surgery in patients with normal preoperative magnetic resonance imaging (MRI).
  
  
  METHODS
  24 adult and paediatric patients with normal preoperative MRIs were studied. They underwent epilepsy surgery between 1994 and 2001 and had at least one year of follow up.
  
  
  RESULTS
  At the most recent follow up, nine patients (37%) were seizure-free and 18 (75%) had at least a 90% reduction in seizure frequency with weekly or monthly seizures. Seizure freedom was not significantly different after resections in frontal (5/9) or temporal regions (4/13) (p = 0.24, Fisher's exact test), or among patients with or without localising features on EEG, PET, or ictal SPECT. Subdural grids, used in 15 of 24 patients, helped tailor resections but were not associated with differences in outcome. Histopathology showed cortical dysplasia in 10 patients (42%), non-specific findings in 13 (54%), and hippocampal sclerosis in one (4%). Cortical dysplasia was seen in seven patients with frontal resection (78%) and non-specific findings in nine (69%) with temporal resection. Seizure outcome did not differ on the basis of location of resection or histopathology.
  
  
  CONCLUSIONS
  While these results were less favourable than expected for patients with focal epileptogenic lesions seen on MRI, they represented worthwhile improvement for this patient population with high preoperative seizure burden. In this highly selected group, no single test or combination of tests further predicted postoperative seizure outcome.
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: K
authors.initials: K
authors.lastname: Chapman
authors.forename: E
authors.initials: E
authors.lastname: Wyllie
authors.forename: I
authors.initials: I
authors.lastname: Najm
authors.forename: P
authors.initials: P
authors.lastname: Ruggieri
authors.forename: W
authors.initials: W
authors.lastname: Bingaman
authors.forename: J
authors.initials: J
authors.lastname: Lüders
authors.forename: P
authors.initials: P
authors.lastname: Kotagal
authors.forename: D
authors.initials: D
authors.lastname: Lachhwani
authors.forename: D
authors.initials: D
authors.lastname: Dinner
authors.forename: H O
authors.initials: HO
authors.lastname: Lüders
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011300:Preoperative Care; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome