title: A novel method for implementation of frameless StereoEEG in epilepsy surgery.
abstract: BACKGROUND
  Stereoelectroencephalography (SEEG) is an invasive diagnostic procedure in epilepsy surgery that is usually implemented with frame-based methods.
  
  
  OBJECTIVE
  To describe a new technique of frameless SEEG and report a prospective case series at a single center.
  
  
  METHODS
  Image integration and planning of electrode trajectories were performed preoperatively on specialized software and exported to a Medtronic S7 StealthStation. Trajectories were implemented by frameless stereotaxy using percutaneous drilling and bolt insertion.
  
  
  RESULTS
  Twenty-two patients went this technique, with the insertion of 187 intracerebral electrodes. Of 187 electrodes, 175 accurately reached their neurophysiological target, as measured by postoperative computed tomography reconstruction and multimodal image integration with preoperative magnetic resonance imaging. Four electrodes failed to hit their target due to extradural deflection, and 3 were subsequently resited satisfactorily. Eight electrodes were off target by a mean of 3.6 mm (range, 0.9-6.8 mm) due to a combination of errors in bolt trajectory implementation and bending of the electrode. There was 1 postoperative hemorrhage that was clinically asymptomatic and no postoperative infections. Sixteen patients were offered definitive cortical resections, and 6 patients were excluded from resective surgery.
  
  
  CONCLUSIONS
  Frameless SEEG is a novel and safe method for implementing SEEG and is easily translated into clinical practice.
authors.affiliation: *Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, United Kingdom; ‡Epilepsy Society, MRI Unit, Chalfont St. Peter, United Kingdom; §Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom; ¶Centre of Medical Imaging and Computing, UCL, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Nowell
authors.forename: Roman
authors.initials: R
authors.lastname: Rodionov
authors.forename: Beate
authors.initials: B
authors.lastname: Diehl
authors.forename: Tim
authors.initials: T
authors.lastname: Wehner
authors.forename: Gergely
authors.initials: G
authors.lastname: Zombori
authors.forename: Jane
authors.initials: J
authors.lastname: Kinghorn
authors.forename: Sebastien
authors.initials: S
authors.lastname: Ourselin
authors.forename: John
authors.initials: J
authors.lastname: Duncan
authors.forename: Anna
authors.initials: A
authors.lastname: Miserocchi
authors.forename: Andrew
authors.initials: A
authors.lastname: McEvoy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D004827:Epilepsy / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D038361:Neuronavigation / Q000295:instrumentation / Q000379:methods*; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult