title: Relationship between laser Doppler signals and anatomy during deep brain stimulation electrode implantation toward the ventral intermediate nucleus and subthalamic nucleus.
abstract: BACKGROUND
  Deep brain stimulation (DBS) requires precise and safe navigation to the chosen target. Optical measurements allow monitoring of gray-white tissue boundaries (total light intensity [TLI]) and microvascular blood flow during stereotactic procedures.
  
  
  OBJECTIVE
  To establish the link between TLI/blood flow and anatomy along trajectories toward the ventral intermediate nucleus (Vim) and subthalamic nucleus (STN).
  
  
  METHODS
  Stereotactic laser Doppler measurements were obtained with millimeter precision from the cortex toward the Vim (n = 13) and STN (n = 9). Optical trajectories of TLI and blood flow were created and compared with anatomy by superimposing the Schaltenbrandt-Wahren atlas on the patients' pre- and postoperative images. Measurements were divided into anatomic subgroups and compared statistically.
  
  
  RESULTS
  Typical TLI trajectories with well-defined anatomic regions could be identified for the Vim and STN. TLI was significantly lower (P < .001) and microvascular blood flow significantly higher (P = .01) in the Vim targets. Of 1285 sites, 38 showed blood flow peaks, 27 of them along the Vim trajectories. High blood flow was more common close to the sulci and in the vicinity of the caudate/putamen. Along 1 Vim trajectory, a slight bleeding was suspected during insertion of the probe and confirmed with postoperative computed tomography.
  
  
  CONCLUSIONS
  Laser Doppler is useful for intraoperative guidance during DBS implantation because simultaneous measurement of tissue grayness and microvascular blood flow can be done along the trajectory with millimeter precision. Typical but different TLI trajectories were found for the Vim and STN.
authors.affiliation: Department of Biomedical Engineering, Linköping University, Linköping, Sweden. karin.wardell@liu.se
authors.forename: Karin
authors.initials: K
authors.lastname: Wårdell
authors.forename: Peter
authors.initials: P
authors.lastname: Zsigmond
authors.forename: Johan
authors.initials: J
authors.lastname: Richter
authors.forename: Simone
authors.initials: S
authors.lastname: Hemm
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000033:anatomy & histology*; D046690:Deep Brain Stimulation / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*