title: Correlation between magnetoencephalography-based "clusterectomy" and postoperative seizure freedom.
abstract: OBJECTIVE
  During the presurgical evaluation of patients with medically intractable focal epilepsy, a variety of noninvasive studies are performed to localize the hypothetical epileptogenic zone and guide the resection. Magnetoencephalography (MEG) is becoming increasingly used in the clinical realm for this purpose. No investigators have previously reported on coregisteration of MEG clusters with postoperative resection cavities to evaluate whether complete "clusterectomy" (resection of the area associated with MEG clusters) was performed or to compare these findings with postoperative seizure-free outcomes.
  
  
  METHODS
  The authors retrospectively reviewed the charts and imaging studies of 65 patients undergoing MEG followed by resective epilepsy surgery from 2009 until 2012 at the Cleveland Clinic. Preoperative MEG studies were fused with postoperative MRI studies to evaluate whether clusters were within the resected area. These data were then correlated with postoperative seizure freedom.
  
  
  RESULTS
  Sixty-five patients were included in this study. The average duration of follow-up was 13.9 months, the mean age at surgery was 23.1 years, and the mean duration of epilepsy was 13.7 years. In 30 patients, the main cluster was located completely within the resection cavity, in 28 it was completely outside the resection cavity, and in 7 it was partially within the resection cavity. Seventy-four percent of patients were seizure free at 12 months after surgery, and this rate decreased to 60% at 24 months. Improved likelihood of seizure freedom was seen with complete clusterectomy in patients with localization outside the temporal lobe (extra-temporal lobe epilepsy) (p = 0.04).
  
  
  CONCLUSIONS
  In patients with preoperative MEG studies that show clusters in surgically accessible areas outside the temporal lobe, we suggest aggressive resection to improve the chances for seizure freedom. When the cluster is found within the temporal lobe, further diagnostic testing may be required to better localize the epileptogenic zone.
authors.affiliation: Department of Neurosurgery, Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195, USA. vaderas@ccf.org
authors.forename: Sumeet
authors.initials: S
authors.lastname: Vadera
authors.forename: Lara
authors.initials: L
authors.lastname: Jehi
authors.forename: Richard C
authors.initials: RC
authors.lastname: Burgess
authors.forename: Katherine
authors.initials: K
authors.lastname: Shea
authors.forename: Andreas V
authors.initials: AV
authors.lastname: Alexopoulos
authors.forename: John
authors.initials: J
authors.lastname: Mosher
authors.forename: Jorge
authors.initials: J
authors.lastname: Gonzalez-Martinez
authors.forename: William
authors.initials: W
authors.lastname: Bingaman
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012640:Seizures / Q000503:physiopathology* / Q000601:surgery*; D013223:Statistics as Topic; D015899:Tomography, Emission-Computed, Single-Photon; D055815:Young Adult