title: Reoperation after failed deep brain stimulation for essential tremor.
abstract: OBJECTIVE
  To evaluate the effects of reoperation with deep brain stimulation (DBS) in the caudal zona incerta (cZi) in patients with failed DBS in the ventral intermediate (Vim) nucleus of the thalamus for essential tremor.
  
  
  METHODS
  The results of reoperation with cZi DBS in five patients with failed Vim DBS were retrospectively analyzed.
  
  
  RESULTS
  Two patients had early failure of Vim DBS, and three after several years of good effect. The mean deviation from the atlas Vim target point was 1.4 mm. Before the reoperation Vim DBS improved hand function and tremor in the treated hand at 25 %, whereas cZi DBS achieved an improvement of 57%. Although cZi was more efficient than Vim DBS, also in the patients with late failure of Vim DBS, they still exhibited a considerable residual tremor on cZi DBS.
  
  
  CONCLUSIONS
  The effect on tremor was, in this small sample population, improved by implanting an electrode in the cZi. The effect was modest in those patients suffering a deterioration years after the initial operation.
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Section of Neurosurgery, Umeå University, Umeå, Sweden. patric.blomstedt@neuro.umu.se
authors.forename: Patric
authors.initials: P
authors.lastname: Blomstedt
authors.forename: Peter
authors.initials: P
authors.lastname: Lindvall
authors.forename: Jan
authors.initials: J
authors.lastname: Linder
authors.forename: Magnus
authors.initials: M
authors.lastname: Olivecrona
authors.forename: Lars
authors.initials: L
authors.lastname: Forsgren
authors.forename: Marwan I
authors.initials: MI
authors.lastname: Hariz
mesh_terms: D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects* / Q000379:methods*; D020329:Essential Tremor / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012086:Reoperation / Q000379:methods*; D012189:Retrospective Studies; D020530:Subthalamus / Q000601:surgery; D017211:Treatment Failure; D020651:Ventral Thalamic Nuclei / Q000601:surgery