title: Electrode location and clinical outcome in hippocampal electrical stimulation for mesial temporal lobe epilepsy.
abstract: OBJECTIVE
  To study the clinical outcome in hippocampal deep brain stimulation (DBS) for the treatment of patients with refractory mesial temporal lobe epilepsy (MTLE) according to the electrode location.
  
  
  METHODS
  Eight MTLE patients implanted in the hippocampus and stimulated with high-frequency DBS were included in this study. Five underwent invasive recordings with depth electrodes to localize ictal onset zone prior to chronic DBS. Position of the active contacts of the electrode was calculated on postoperative imaging. The distances to the ictal onset zone were measured as well as atlas-based hippocampus structures impacted by stimulation were identified. Both were correlated with seizure frequency reduction.
  
  
  RESULTS
  The distances between active electrode location and estimated ictal onset zone were 11±4.3 or 9.1±2.3mm for patients with a >50% or <50% reduction in seizure frequency. In patients (N=6) showing a >50% seizure frequency reduction, 100% had the active contacts located <3mm from the subiculum (p<0.05). The 2 non-responders patients were stimulated on contacts located >3mm to the subiculum.
  
  
  CONCLUSIONS
  Decrease of epileptogenic activity induced by hippocampal DBS in refractory MTLE: (1) seems not directly associated with the vicinity of active electrode to the ictal focus determined by invasive recordings; (2) might be obtained through the neuromodulation of the subiculum.
authors.affiliation: Department of Neurosurgery, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Percy
authors.initials: P
authors.lastname: Bondallaz
authors.forename: Colette
authors.initials: C
authors.lastname: Boëx
authors.forename: Andrea O
authors.initials: AO
authors.lastname: Rossetti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Foletti
authors.forename: Laurent
authors.initials: L
authors.lastname: Spinelli
authors.forename: Serge
authors.initials: S
authors.lastname: Vulliemoz
authors.forename: Margitta
authors.initials: M
authors.lastname: Seeck
authors.forename: Claudio
authors.initials: C
authors.lastname: Pollo
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D046690:Deep Brain Stimulation / Q000379:methods; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000628:therapy*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000473:pathology; D016896:Treatment Outcome