title: Relationship of stimulation site location within the subthalamic nucleus region to clinical effects on parkinsonian symptoms.
abstract: OBJECTIVE
  To determine the relationship of the stimulation site in the subthalamic region to the clinical effects on parkinsonian symptoms, the monopolar stimulation of 4 electrode contacts and the resulting effects on parkinsonian symptoms were evaluated.
  
  
  METHODS
  Seventeen consecutive patients (3 males and 14 females) were enrolled in the study. The patients were evaluated while in a nonmedicated state, and 10-20 min after switching on the pulse generator the effects of stimulation were assessed using separate-subset Unified Parkinson's Disease Rating Scale scores.
  
  
  RESULTS
  The relationship between the site stimulated and the percent improvement was analyzed using polynomial regression. Rigidity (p = 0.0004, R2 = 0.15), akinesia (p = 0.02, R2 = 0.07) and total score (p = 0.009, R2 = 0.089) well fit to second-order polynomial regression and showed the greatest improvement after stimulation at 0-1 mm below the horizontal anterior-posterior commissure (AC-PC) plane. Tremor (p = 0.24, R2 = 0.18) and gait (p = 0.36, R2 = 0.001) had a weak relation to the site stimulated, but stimulation at the sites 0-1 mm below the AC-PC plane also produced greater improvement than stimulation at more ventral or dorsal sites. The percent improvement of the posture (p = 0.92, R2 = 0.002) had no relation to the site stimulated. The dorsal border of the subthalamic nucleus was located 0.6 +/- 1.2 mm (n = 27) below the AC-PC plane and the most effective electrode contact 1.2 +/- 1.3 mm (n = 27) below it.
  
  
  CONCLUSIONS
  Stimulation around the dorsal border of the subthalamic nucleus, close to the AC-PC plane, produces greater improvement of parkinsonian symptoms than stimulation at more ventral or dorsal sites.
authors.affiliation: Department of Neurosurgery, Hamamatsu University School of Medicine, Hamamatsu, Japan. yokoyama-t@maotv.ne.jp
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Naoto
authors.initials: N
authors.lastname: Ando
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugiyama
authors.forename: Soichi
authors.initials: S
authors.lastname: Akamine
authors.forename: Hiroki
authors.initials: H
authors.lastname: Namba
mesh_terms: D000368:Aged; D001931:Brain Mapping; D046690:Deep Brain Stimulation / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy*; D012044:Regression Analysis; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000503:physiopathology*; D016896:Treatment Outcome