title: Deep brain stimulation of the ventral intermediate nucleus in patients with essential tremor: stimulation below intercommissural line is more efficient but equally effective as stimulation above.
abstract: BACKGROUND
  The posterior subthalamic area (PSA), ventral to the intercommissural line (ICL) and the ventral intermediate nucleus (VIM), has been suggested as a promising target for deep brain stimulation (DBS) in patients suffering from essential tremor (ET). In this study the clinical benefit of VIM and PSA DBS on postural tremor suppression was systematically evaluated in a two step approach with a 3D ultrasound kinematic analysis tool.
  
  
  METHODS
  We defined the exact position of 40 VIM-DBS-electrodes from 21 ET patients. In a first experiment with a subgroup of electrodes we subsequently activated a thalamic and a contact below ICL (sub-ICL) with equal parameter settings for within subject comparison. In a second step, we divided all electrodes into two groups, i.e. one group with activated thalamic and the other group with activated contacts below ICL and performed a group comparison under patients' individual stimulation parameters. Here, the corrected amplitude required for tremor suppression was analyzed separately for both groups.
  
  
  RESULTS
  Within subject comparison with equal parameter settings revealed a significant improvement of sub-ICL compared to thalamic stimulation. In contrast, group comparison under patients' individual stimulation did not show any significant difference in tremor suppression between VIM and PSA DBS. Although higher corrected stimulation amplitude was needed in the thalamic group this difference was not significant.
  
  
  CONCLUSIONS
  The data suggest that sub-ICL stimulation may be more efficient compared to thalamic stimulation but equally effective when patients' individual stimulation parameters are used.
authors.affiliation: Department of Neurology, University Hospital Cologne, Cologne, Germany. michael.barbe@uk-koeln.de
authors.forename: Michael T
authors.initials: MT
authors.lastname: Barbe
authors.forename: Lena
authors.initials: L
authors.lastname: Liebhart
authors.forename: Matthias
authors.initials: M
authors.lastname: Runge
authors.forename: Janina
authors.initials: J
authors.lastname: Deyng
authors.forename: Esther
authors.initials: E
authors.lastname: Florin
authors.forename: Lars
authors.initials: L
authors.lastname: Wojtecki
authors.forename: Alfons
authors.initials: A
authors.lastname: Schnitzler
authors.forename: Niels
authors.initials: N
authors.lastname: Allert
authors.forename: Volker
authors.initials: V
authors.lastname: Sturm
authors.forename: Gereon R
authors.initials: GR
authors.lastname: Fink
authors.forename: Mohammad
authors.initials: M
authors.lastname: Maarouf
authors.forename: Lars
authors.initials: L
authors.lastname: Timmermann
mesh_terms: D046690:Deep Brain Stimulation / Q000379:methods*; D004566:Electrodes; D020329:Essential Tremor / Q000628:therapy*; D006801:Humans; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D020651:Ventral Thalamic Nuclei / Q000033:anatomy & histology / Q000502:physiology*