title: Effect of epilepsy magnetic source imaging on intracranial electrode placement.
abstract: OBJECTIVE
  Intracranial electroencephalography (ICEEG) with chronically implanted electrodes is a costly invasive diagnostic procedure that remains necessary for a large proportion of patients who undergo evaluation for epilepsy surgery. This study was designed to evaluate whether magnetic source imaging (MSI), a noninvasive test based on magnetoencephalography source localization, can supplement ICEEG by affecting electrode placement to improve sampling of the seizure onset zone(s).
  
  
  METHODS
  Of 298 consecutive epilepsy surgery candidates (between 2001 and 2006), 160 patients were prospectively enrolled by insufficient localization from seizure monitoring and magnetic resonance imaging results. Before presenting MSI results, decisions were made whether to proceed with ICEEG, and if so, where to place electrodes such that the hypothetical seizure-onset zone would be sampled. MSI results were then provided with allowance of changes to the original plan.
  
  
  RESULTS
  MSI indicated additional electrode coverage in 18 of 77 (23%) ICEEG cases. In 39% (95% confidence interval, 16.4-61.4), seizure-onset ICEEG patterns involved the additional electrodes indicated by MSI. Sixty-two patients underwent surgical resection based on ICEEG recording of seizures. Highly localized MSI was significantly associated with seizure-free outcome (mean, 3.4 years; minimum, >1 year) for the entire surgical population (n = 62).
  
  
  CONCLUSIONS
  MSI spike localization increases the chance that the seizure-onset zone is sampled when patients undergo ICEEG for presurgical epilepsy evaluations. The clinical impact of this effect, improving diagnostic yield of ICEEG, should be considered in surgery candidates who do not have satisfactory indication of epilepsy localization from seizure semiology, electroencephalogram, and magnetic resonance imaging.
authors: Epilepsy Center, Department of Neurology, University of Alabama at Birmingham, School of Medicine, Birmingham, AL 35294-0001, USA. knowlton@uab.edu
authors: Robert C
authors: RC
authors: Knowlton
authors: Shantanu N
authors: SN
authors: Razdan
authors: Nita
authors: N
authors: Limdi
authors: Rotem A
authors: RA
authors: Elgavish
authors: Jeff
authors: J
authors: Killen
authors: Jeffrey
authors: J
authors: Blount
authors: Jorge G
authors: JG
authors: Burneo
authors: Lawrence
authors: L
authors: Ver Hoef
authors: Lebron
authors: L
authors: Paige
authors: Edward
authors: E
authors: Faught
authors: Pongkiat
authors: P
authors: Kankirawatana
authors: Al
authors: A
authors: Bartolucci
authors: Kristen
authors: K
authors: Riley
authors: Ruben
authors: R
authors: Kuzniecky
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology* / Q000601:surgery; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods; D004827:Epilepsy / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007223:Infant; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods; D011446:Prospective Studies; D055815:Young Adult