title: Location of the active contact within the subthalamic nucleus (STN) in the treatment of idiopathic Parkinson's disease.
abstract: BACKGROUND
  Chronic electrical stimulation of the subthalamic nucleus (STN) has been shown to be safe and effective in the treatment of medically refractory idiopathic Parkinson's disease. The clinically most relevant location of stimulation within the physiologically defined STN has not been confirmed. We reviewed the locations of active electrical contacts in 33 patients who underwent simultaneous bilateral STN deep brain stimulator (DBS) implantation.
  
  
  METHODS
  The location of the microelectrode-defined dorsal STN border was compared to the location of the center of the active contact(s) employed in achieving optimal clinical results 6 to 18 months postoperatively. Furthermore, the location of this optimal contact was determined with respect to each individual patient's midcommissural point. Bilateral monopolar stimulation was employed in 30 patients using quadripolar DBS electrodes.
  
  
  RESULTS
  After a minimum follow-up period of 6 months, the motor subscores (UPDRS Part III) in the postoperative on-stimulation/off-medication state were 64 +/- 18% (mean +/- SD) improved as compared to the preoperative off-medication state (p < 0.01). Additionally, an improvement of 53 +/- 38% was noted when comparing the postoperative on-stimulation/on-medication state to the preoperative on-medication state (p < 0.01). On average, the center of the optimal contact was 13.3 mm lateral, 0.5 mm posterior, 0.1 mm inferior to the mid-commissural point and was 0.1 +/- 2.1 mm dorsal to the physiologically defined dorsal STN border.
  
  
  CONCLUSIONS
  While the achieved clinical results are comparable to those published in the literature, it appears that monopolar electrical stimulation at the anterior dorsolateral border of the STN yields optimal clinical results. Further studies are crucial in determining the precise mechanism of various modes of DBS in an effort to maximize clinical outcome.
authors.affiliation: New York University Center for Functional and Restorative Neurosurgery, New York, New York, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Zonenshayn
authors.forename: Djordje
authors.initials: D
authors.lastname: Sterio
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Kelly
authors.forename: Ali R
authors.initials: AR
authors.lastname: Rezai
authors.forename: Aleksander
authors.initials: A
authors.lastname: Beric
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D004599:Electric Stimulation Therapy; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery