title: Gamma knife thalamotomy for Parkinson disease and essential tremor:  a prospective multicenter study.
abstract: BACKGROUND
  No prospective study of gamma knife thalamotomy for intractable tremor has previously been reported.
  
  
  OBJECTIVE
  To clarify the safety and optimally effective conditions for performing unilateral gamma knife (GK) thalamotomy for tremors of Parkinson disease (PD) and essential tremor (ET), a systematic postirradiation 24-month follow-up study was conducted at 6 institutions. We present the results of this multicenter collaborative trial.
  
  
  METHODS
  In total, 72 patients (PD characterized by tremor, n = 59; ET, n = 13) were registered at 6 Japanese institutions. Following our selective thalamotomy procedure, the lateral part of the ventralis intermedius nucleus, 45% of the thalamic length from the anterior tip, was selected as the GK isocenter. A single 130-Gy shot was applied using a 4-mm collimator. Evaluation included neurological examination, magnetic resonance imaging and/or computerized tomography, the unified Parkinson's disease rating scale (UPDRS), electromyography, medication change, and video observations.
  
  
  RESULTS
  Final clinical effects were favorable. Of 53 patients who completed 24 months of follow-up, 43 were evaluated as having excellent or good results (81.1%). UPDRS scores showed tremor improvement (parts II and III). Thalamic lesion size fluctuated but converged to either an almost spherical shape (65.6%), a sphere with streaking (23.4%), or an extended high-signal zone (10.9%). No permanent clinical complications were observed.
  
  
  CONCLUSIONS
  GK thalamotomy is an alternative treatment for intractable tremors of PD as well as for ET. Less invasive intervention may be beneficial to patients.
authors: Functional and Gamma Knife Surgery Center, Hidaka Hospital, Takasaki, Japan.
authors: Chihiro
authors: C
authors: Ohye
authors: Yoshinori
authors: Y
authors: Higuchi
authors: Toru
authors: T
authors: Shibazaki
authors: Takao
authors: T
authors: Hashimoto
authors: Toru
authors: T
authors: Koyama
authors: Tatsuo
authors: T
authors: Hirai
authors: Shinji
authors: S
authors: Matsuda
authors: Toru
authors: T
authors: Serizawa
authors: Tomokatsu
authors: T
authors: Hori
authors: Motohiro
authors: M
authors: Hayashi
authors: Taku
authors: T
authors: Ochiai
authors: Hirofumi
authors: H
authors: Samura
authors: Katsumi
authors: K
authors: Yamashiro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020329:Essential Tremor / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis / Q000601:surgery*; D011446:Prospective Studies; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome; D020651:Ventral Thalamic Nuclei / Q000601:surgery*