title: Safety and usefulness of insular depth electrodes implanted via an oblique approach in patients with epilepsy.
abstract: OBJECTIVE
  This study investigates the feasibility, safety, and usefulness of depth electrodes stereotactically implanted within the insular cortex.
  
  
  METHODS
  Thirty patients with suspected insular involvement during epileptic seizure underwent presurgical stereotactic electroencephalographic recordings using 10 to 16 depth electrodes per patient. Among these, one or two electrodes were implanted via an oblique approach to widely sample the insular cortex.
  
  
  RESULTS
  Thirty-five insular electrodes were implanted in the 30 patients without morbidity. A total of 226 recording contacts (mean, 7.5 contacts/patient) explored the insular cortex. Stereotactic electroencephalographic recordings of seizures allowed the differentiation into groups: Group 1, 10 patients with no insular involvement; Group 2, 15 patients with secondary insular involvement; and Group 3, five patients with an initial insular involvement. In temporal epilepsy (n = 17), the insula was never involved at the seizure onset but was frequently involved during the seizures (11 out of 17). In frontotemporal or frontal epilepsy, the insula was involved at the onset of seizure in five out of 13 patients. All patients in Groups 1 and 2 underwent surgery, with a seizure-free outcome in 76.2% of patients. In Group 3, only two of the five patients underwent surgery, with a poor outcome. In temporal lobe epilepsy, surgical outcome tended to be better in Group 1 compared with Group 2 in this small series: results were good in 83.3% (Engel I) versus 72.7%.
  
  
  CONCLUSIONS
  Insula can be safely explored with oblique electrodes. In temporal lobe epilepsy, insular involvement does not significantly modify the short-term postoperative outcome. Future larger studies are necessary to clarify the long-term prognostic value of insular spread.
authors.affiliation: Department of Neurological Surgery, and INSERM U836, Grenoble University Hospital, Grenoble, France.
authors.forename: Afif
authors.initials: A
authors.lastname: Afif
authors.forename: Stephan
authors.initials: S
authors.lastname: Chabardes
authors.forename: Lorella
authors.initials: L
authors.lastname: Minotti
authors.forename: Philippe
authors.initials: P
authors.lastname: Kahane
authors.forename: Dominique
authors.initials: D
authors.lastname: Hoffmann
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D046690:Deep Brain Stimulation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D004567:Electrodes, Implanted; D004827:Epilepsy / Q000517:prevention & control*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation / Q000009:adverse effects / Q000379:methods*; D013238:Stereotaxic Techniques; D016896:Treatment Outcome