title: Minimizing brain shift in stereotactic functional neurosurgery.
abstract: BACKGROUND
  Stereotactic functional neurosurgical interventions depend on precise anatomic targeting before lesioning or deep brain stimulation (DBS) electrode placement.
  
  
  OBJECTIVE
  To examine the degree of subcortical brain shift observed when adopting an image-guided approach to stereotactic functional neurosurgery.
  
  
  METHODS
  Coordinates for the anterior and posterior commissural points (AC and PC) were recorded on thin-slice stereotactic magnetic resonance imaging (MRI) scans performed before and immediately after DBS electrode implantation in 136 procedures. The changes in length of AC-PC and in stereotactic coordinates for AC and PC were calculated for each intervention. In patients with Parkinson disease undergoing bilateral subthalamic nucleus (STN) DBS with at least 6 months of follow-up, pre- and postoperative scores of the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS-III) were reviewed.
  
  
  RESULTS
  Mean (SD) change in AC-PC length (DeltaAC-PC) was 0.6 (0.4) mm. There was no statistically significant difference in DeltaAC-PC between groups when examining anatomic target subgroups (P =.95), age subgroups (P = .63), sex (P = .59), and unilateral versus bilateral implantation (P =.15). The mean (SD) vector changes for the commissural points were: -0.1 (0.3) mm in X, -0.4 (0.6) mm in Y, and -0.1 (0.7) mm in Z for the AC; and -0.1 (0.3) mm in X, -0.2 (0.7) mm in Y, and 0.0 (0.7) mm in Z for the PC. There was a negligible correlation between the magnitude of brain shift and percentage improvement in UPDRS-III off-medication in patients undergoing STN DBS for PD (R <0.01).
  
  
  CONCLUSIONS
  Brain shift has long been considered an issue in stereotactic targeting during DBS procedures. However, with the image-guided approach and surgical technique used in this study, subcortical brain shift was extremely limited and did not appear to adversely affect clinical outcome.
authors.affiliation: Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, Queen Square, London, UK.
authors.forename: Erika A
authors.initials: EA
authors.lastname: Petersen
authors.forename: Etienne M
authors.initials: EM
authors.lastname: Holl
authors.forename: Irene
authors.initials: I
authors.lastname: Martinez-Torres
authors.forename: Thomas
authors.initials: T
authors.lastname: Foltynie
authors.forename: Patricia
authors.initials: P
authors.lastname: Limousin
authors.forename: Marwan I
authors.initials: MI
authors.lastname: Hariz
authors.forename: Ludvic
authors.initials: L
authors.lastname: Zrinzo
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000758:Anesthesia / Q000379:methods; D046690:Deep Brain Stimulation / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D010300:Parkinson Disease / Q000503:physiopathology / Q000601:surgery / Q000628:therapy*; D011007:Pneumocephalus / Q000209:etiology; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000502:physiology*; D016896:Treatment Outcome; D055815:Young Adult