title: Discrepancies between the MRI- and the electrophysiologically defined subthalamic nucleus.
abstract: BACKGROUND
  The aim of our study was to evaluate discrepancies between the electrophysiologically and MRI-defined subthalamic nucleus (STN) in order to contribute to the ongoing debate of whether or not microelectrode recording (MER) provides additional information to image-guided targeting in deep brain stimulation.
  
  
  METHODS
  Forty-four STNs in 22 patients with Parkinson's disease were investigated. The three-dimensional MRI-defined STN was derived from segmentations of axial and coronal T2-weighted images. The electrophysiological STNs were generated from intraoperative MERs in 1,487 locations. The stereotactical coordinates of positive and negative STN recordings were re-imported to the planning software, where a three-dimensional reconstruction of the electrophysiological STN was performed and fused to the MRI data set. The estimated borders of the MRI- and MER-STN were compared. For statistical analysis Student's t, Mann-Whitney rank sum and Fisher's exact tests were used.
  
  
  RESULTS
  MER-STN volumes, which were found outside the MRI-STN, ranged from 0 mm(3) to 87 mm(3) (mean: 45 mm(3)). A mean of 44% of the MER-STN volumes exceeded the MRI-STN (maximum: 85.1%; minimum: 15.1 %); 53.4% (n = 793) of the microelectrode recordings were concordant and 46.6% (n = 694) discordant with the MRI-defined anatomical STN. Regarding the dorsal borders, we found discrepancies between the MER- and MRI-STN of 0.27 mm (= mean; SD: 0.51 mm) on the first operated side and 1.51 mm (SD: 1.5 mm) on the second (p = 0.010, t-test).
  
  
  CONCLUSIONS
  MER provides additional information to high-resolution anatomical MR images and may help to detect the amount and direction of brain shift.
authors: Department of Neurosurgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany. juergen.schlaier@klinik.uni-regensburg.de
authors: Juergen Ralf
authors: JR
authors: Schlaier
authors: Christine
authors: C
authors: Habermeyer
authors: Jan
authors: J
authors: Warnat
authors: Max
authors: M
authors: Lange
authors: Annette
authors: A
authors: Janzen
authors: Andreas
authors: A
authors: Hochreiter
authors: Martin
authors: M
authors: Proescholdt
authors: Alexander
authors: A
authors: Brawanski
authors: Claudia
authors: C
authors: Fellner
mesh_terms: D000368:Aged; D046690:Deep Brain Stimulation / Q000379:methods*; D004594:Electrophysiology / Q000379:methods / Q000592:standards*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*; D010300:Parkinson Disease / Q000628:therapy*; D012189:Retrospective Studies; D020531:Subthalamic Nucleus / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery