title: Prognostic value of insular lobe involvement in temporal lobe epilepsy: a stereoelectroencephalographic study.
abstract: OBJECTIVE
  Failure of anterior temporal lobectomy for temporal lobe epilepsy has raised the question of insular cortex involvement in these seizures. Because of difficulties in exploring the insula with invasive electroencephalography (EEG) recordings, only few studies have been performed and this question remains unanswered.
  
  
  METHODS
  Here, we studied 17 patients who underwent surgery for drug-resistant temporal lobe epilepsy, explored with intracerebral electrodes, with at least one electrode coplanar to the insula. We analyzed seizure propagation patterns from temporal lobe structures to the insula, and their effect on outcome. We used an objective measure of the epileptogenicity of the insula for individual cases and group analysis between patients who were seizure-free after surgery and the others.
  
  
  RESULTS
  All temporal lobe seizures propagated to the insular cortex, with a shorter propagation delay in the case of mesiolateral temporal lobe seizures, thus supporting the existence of a perilimbic network. Epileptogenicity of the insular cortex was not a prognostic factor for outcome after surgery.
  
  
  CONCLUSIONS
  Insular involvement in temporal lobe seizure is not per se a prognostic factor for surgical outcome. Prognosis may be correlated with larger epileptogenic zones that our stereoelectroencephalography spatial sampling could have underestimated.
authors.affiliation: Department of Pediatric Neurosurgery, APHP, Hospital Necker, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Blauwblomme
authors.forename: Olivier
authors.initials: O
authors.lastname: David
authors.forename: Lorella
authors.initials: L
authors.lastname: Minotti
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Job
authors.forename: Serge
authors.initials: S
authors.lastname: Chassagnon
authors.forename: Dominique
authors.initials: D
authors.lastname: Hoffman
authors.forename: Stéphan
authors.initials: S
authors.lastname: Chabardes
authors.forename: Philippe
authors.initials: P
authors.lastname: Kahane
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000601:surgery*; D002648:Child; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016896:Treatment Outcome; D055815:Young Adult
keywords: Epilepsy surgery; Epileptogenic index; Insula; Stereotactic intracerebral electroencephalographic; Temporal lobe epilepsy