title: The impact of stereotactic pallidal surgery on the dopamine D2 receptor in Parkinson disease: a positron emission tomography study.
abstract: OBJECTIVE
  The aim of this study was to estimate the impact of stereotactic pallidal surgery on the binding potential of dopamine D2 receptors in patients with advanced Parkinson disease (PD).
  
  
  METHODS
  Six patients with advanced PD (three men and three women; mean age 56.7 +/- 9.8 years, Hoehn and Yahr stage 3.3 +/- 1.1/3.9 +/- 1.2 [on/off scores], mean +/- standard deviation) underwent stereotactic pallidal surgery. One underwent right posteroventral pallidotomy (PVP), one received left PVP, three were treated with deep brain stimulation (DBS) of the left globus pallidus internus (GPi), and one with bilateral DBS of the GPi. The binding potential of the dopamine D2 receptors of these patients was determined before and after surgery by using positron emission tomography scanning with 11C-nemonapride and it was compared with the value in eight healthy volunteers. The authors also examined whether changes in the D2 receptor binding potential were correlated with the clinical outcome. The clinical symptoms, especially those in the off state, were significantly improved after surgery. Preoperatively, the D2 receptor binding potential in the putamen was elevated by 27% (p < 0.01) and that in the thalamus was 29% lower than that in controls (p < 0.01). The D2 receptor binding potential in the putamen and thalamus returned to control levels after surgery. The preoperative level of the D2 receptor binding potential in the anterior cingulate cortex was comparable to that of controls, but it declined significantly after surgery, whereas the D2 receptor binding potential in other regions of both hemispheres showed no significant changes after surgery. Although the D2 receptor binding potential did not correlate with the Hoehn and Yahr stage, the Schwab and England score, or the Unified PD Rating Scale (UPDRS) score, a positive correlation was seen between the percent improvement rate of the total UPDRS score in the off state and the percentage change of the D2 receptor binding potential in the putamen (r = 0.773, p = 0.0417 according to the Pearson linear correlation).
  
  
  CONCLUSIONS
  The altered dopamine D2 receptor binding potential in the putamen might play a crucial role in clinical improvement after PVP or DBS of the GPi in advanced PD.
authors.affiliation: Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakajima
authors.forename: Taro
authors.initials: T
authors.lastname: Nimura
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ando
authors.forename: Masatyoshi
authors.initials: M
authors.lastname: Itoh
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Reizo
authors.initials: R
authors.lastname: Shirane
mesh_terms: D000368:Aged; D001549:Benzamides / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004599:Electric Stimulation Therapy; D005260:Female; D005917:Globus Pallidus / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D011699:Putamen / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology; D013238:Stereotaxic Techniques; D014055:Tomography, Emission-Computed
chemical_list: D001549:Benzamides; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; C030265:nemonapride