title: Analysis of electrode deformations in deep brain stimulation surgery.
abstract: OBJECTIVE
  Deep brain stimulation (DBS) surgery is used to reduce motor symptoms when movement disorders are refractory to medical treatment. Post-operative brain morphology can induce electrode deformations as the brain recovers from an intervention. The inverse brain shift has a direct impact on accuracy of the targeting stage, so analysis of electrode deformations is needed to predict final positions.
  
  
  METHODS
  DBS electrode curvature was evaluated in 76 adults with movement disorders who underwent bilateral stimulation, and the key variables that affect electrode deformations were identified. Non-linear modelling of the electrode axis was performed using post-operative computed tomography (CT) images. A mean curvature index was estimated for each patient electrode. Multivariate analysis was performed using a regression decision tree to create a hierarchy of predictive variables. The identification and classification of key variables that determine electrode curvature were validated with statistical analysis.
  
  
  RESULTS
  The principal variables affecting electrode deformations were found to be the date of the post-operative CT scan and the stimulation target location. The main pathology, patient's gender, and disease duration had a smaller although important impact on brain shift.
  
  
  CONCLUSIONS
  The principal determinants of electrode location accuracy during DBS procedures were identified and validated. These results may be useful for improved electrode targeting with the help of mathematical models.
authors.affiliation: Unite INSERM U1099 LTSI, Equipe Medicis, Faculté de médecine, Université Rennes I, 2 Av. du Pr Leon Bernard, 35043 , Rennes, France, flo.lalys@hotmail.fr.
authors.forename: Florent
authors.initials: F
authors.lastname: Lalys
authors.forename: Claire
authors.initials: C
authors.lastname: Haegelen
authors.forename: Tiziano
authors.initials: T
authors.lastname: D'albis
authors.forename: Pierre
authors.initials: P
authors.lastname: Jannin
mesh_terms: D000328:Adult; D046690:Deep Brain Stimulation / Q000295:instrumentation*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000175:diagnosis / Q000628:therapy*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*