title: Bilateral thalamic stimulation for the treatment of essential tremor.
abstract: OBJECTIVE
  To determine the safety and efficacy of bilateral thalamic stimulation in the treatment of essential tremor (ET).
  
  
  METHODS
  Nine ET patients with disabling tremor refractory to pharmacotherapy underwent bilateral staged implants. Tremor was assessed by the Fahn-Tolosa-Marin Tremor Rating Scale at baseline 1 (before first implant), baseline 2 (before second implant), and at 6-month and 1-year follow-up. Blinded evaluations were performed at 3 months. Associated changes in speech were evaluated in six patients. There were seven men and two women with a mean age of 73.8 years.
  
  
  RESULTS
  There was a significant improvement in the mean total tremor score from a baseline of 66.1+/-11.6 to 28.4+/-12.8 12 months after the second surgery. Similarly, the mean motor tremor subscore was 20.1+/-5.0 before the first surgery and improved significantly to 14.1+/-3.6 before the second surgery. Motor tremor scores 6 months after the second surgery (6.0+/-3.7) and 12 months after the second surgery (7.5+/-3.9) also improved significantly relative to the preoperative scores. The mean activities of daily living (ADL) subscore at baseline was 18.2+/-2.9 and improved significantly before the second surgery to 9.0+/-3.2. These ADL scores further improved 6 months (6.2+/-5.2) and 12 months (7.9+/-5.7) following the second surgery, but these gains were not significant. Blinded evaluations also revealed a similar degree of improvement. Complications were noted in five patients: asymptomatic intracranial hematoma (1), postoperative seizures (1), a hematoma over the implanted pulse generator (IPG) (1), lead repositioning (1), and IPG malfunction (1). Adverse effects related to stimulation were mild and resolved with adjustment of the stimulation parameters. Three of the six patients demonstrated worsening of dysarthria with both stimulators on.
  
  
  CONCLUSIONS
  Bilateral thalamic stimulation is effective in reducing tremor and functional disability in ET; however, dysarthria is a possible complication.
authors.affiliation: Department of Neurology, University of Kansas Medical Center, Kansas City 66160, USA. rpahwa@kumc.edu
authors.forename: R
authors.initials: R
authors.lastname: Pahwa
authors.forename: K L
authors.initials: KL
authors.lastname: Lyons
authors.forename: S B
authors.initials: SB
authors.lastname: Wilkinson
authors.forename: M A
authors.initials: MA
authors.lastname: Carpenter
authors.forename: A I
authors.initials: AI
authors.lastname: Tröster
authors.forename: J P
authors.initials: JP
authors.lastname: Searl
authors.forename: J
authors.initials: J
authors.lastname: Overman
authors.forename: S
authors.initials: S
authors.lastname: Pickering
authors.forename: W C
authors.initials: WC
authors.lastname: Koller
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D004311:Double-Blind Method; D004351:Drug Resistance; D004599:Electric Stimulation Therapy / Q000009:adverse effects; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D011183:Postoperative Complications; D012720:Severity of Illness Index; D013060:Speech; D013788:Thalamus / Q000503:physiopathology*; D014202:Tremor / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery / Q000628:therapy*