title: Does SISCOM contribute to favorable seizure outcome after epilepsy surgery?
abstract: OBJECTIVE
  To assess the additional value of subtraction ictal single-photon emission computed tomography (SPECT) coregistered to MRI (SISCOM) for localization of the epileptogenic zone in patients with drug-resistant epilepsy scheduled for invasive video-EEG (VEEG) before epilepsy surgery by a descriptive study from clinical practice.
  
  
  METHODS
  Forty-nine consecutive epilepsy patients between January 2000 and March 2006 were included. Thirty-six of the 49 patients were offered surgery, and 34 underwent resective surgery during the study period. Localizing and outcome data are presented from 31 patients with a follow-up period of >or=12 months. Successful ictal SPECT was performed in 26 patients, and SISCOM showed significant hyperperfusions with 3.5 SD above reference. Twenty patients had SISCOM-guided electrode placement, invasive monitoring, and 1-year postsurgical follow-up data. Two independent epileptologists evaluated whether SISCOM results (a) altered the hypothesis and extended the strategy for electrode placement at invasive recording, or (b) were confirmatory of other localizing data and did not alter the strategy. We defined that SISCOM had an impact on seizure outcome if the seizure-onset zone was seen in electrodes overlying a brain region with a significant hyperperfusion. When SISCOM was concordant with ictal onset in the extended electrodes, SISCOM was considered a prerequisite for the outcome at postoperative follow-up.
  
  
  RESULTS
  SISCOM findings altered and extended the strategy for electrode placement at invasive recording in 15 patients (group A). SISCOM was a prerequisite for seizure outcome in all six patients with favorable outcomes. Nine patients had poor results from surgery in this group; SISCOM was concordant with invasive VEEG in six patients, and discordant with invasive VEEG in three patients. SISCOM findings were confirmatory with other localizing data and did not alter the strategy at invasive recording in five patients (group B). Two patients had favorable surgical outcomes. In this group, three patients had poor results; SISCOM and other localizing findings were concordant with invasive VEEG in one patient and discordant with invasive VEEG in two patients.
  
  
  CONCLUSIONS
  SISCOM is valuable for the identification of the epileptogenic zone in patients with drug-resistant epilepsy scheduled for invasive VEEG. SISCOM analysis was either a prerequisite for favorable result or concordant with other localizing methods in all patients with favorable seizure outcome at 1 year of follow-up [40%; confidence interval (CI), 19-64).
authors.affiliation: Department of Clinical Neurophysiology, Lund University, Lund, Sweden.
authors.forename: Jan-Anders
authors.initials: JA
authors.lastname: Ahnlide
authors.forename: Ingmar
authors.initials: I
authors.lastname: Rosén
authors.forename: Pernilla
authors.initials: P
authors.lastname: Lindén-Mickelsson Tech
authors.forename: Kristina
authors.initials: K
authors.lastname: Källén
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D013238:Stereotaxic Techniques; D013382:Subtraction Technique; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000706:statistics & numerical data; D016896:Treatment Outcome; D014743:Videotape Recording
chemical_list: D019690:Technetium Tc 99m Exametazime