title: Stimulation-induced side effects in the posterior subthalamic area: distribution, characteristics and visualization.
abstract: OBJECTIVE
  The posterior subthalamic area (PSA) is an emerging but relatively unexplored target for DBS treatment of tremor. The aim of the study was to explore the area further by evaluating the spatial distribution and the characteristics of stimulation-induced side effects in this area.
  
  
  METHODS
  Twenty-eight patients with essential tremor (ET) implanted with 33 DBS electrodes were evaluated concerning stimulation-induced side effects by testing each contact separately one year after surgery. The location of the side effects were plotted on axial slides of the Morel Stereotactic Atlas and a 3-dimensional model of the area for visualization was created.
  
  
  RESULTS
  Visualization of the contacts eliciting stimulation-induced side effects demonstrated that identical responses can be elicited from various points in the PSA and its vicinity. The majority of contacts inducing muscular affection and cerebellar symptoms, including dysarthria, could not be attributed to an effect on the internal capsule. Paresthesias, affecting various body parts were elicited throughout the area without a clear somatotopic pattern.
  
  
  CONCLUSIONS
  Stimulation-induced side effects in the PSA and its vicinity were difficult to attribute to certain anatomical areas as the same response was induced from various locations. Therefore, this study could not provide a meaningful somatotopic map with regard to stimulation-induced side effects in the PSA.
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Neurosurgery, Umeå University, Umeå, Sweden. anders.fytagoridis@neuro.umu.se
authors.forename: A
authors.initials: A
authors.lastname: Fytagoridis
authors.forename: M
authors.initials: M
authors.lastname: Åström
authors.forename: K
authors.initials: K
authors.lastname: Wårdell
authors.forename: P
authors.initials: P
authors.lastname: Blomstedt
mesh_terms: D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D004401:Dysarthria / Q000209:etiology; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D010292:Paresthesia / Q000209:etiology; D020531:Subthalamic Nucleus / Q000502:physiology / Q000601:surgery*; D016896:Treatment Outcome; D014202:Tremor / Q000175:diagnosis / Q000628:therapy*