title: Does navigated transcranial stimulation increase the accuracy of tractography? A prospective clinical trial based on intraoperative motor evoked potential monitoring during deep brain stimulation.
abstract: BACKGROUND
  Tractography based on diffusion tensor imaging has become a popular tool for delineating white matter tracts for neurosurgical procedures.
  
  
  OBJECTIVE
  To explore whether navigated transcranial magnetic stimulation (nTMS) might increase the accuracy of fiber tracking.
  
  
  METHODS
  Tractography was performed according to both anatomic delineation of the motor cortex (n = 14) and nTMS results (n = 9). After implantation of the definitive electrode, stimulation via the electrode was performed, defining a stimulation threshold for eliciting motor evoked potentials recorded during deep brain stimulation surgery. Others have shown that of arm and leg muscles. This threshold was correlated with the shortest distance between the active electrode contact and both fiber tracks. Results were evaluated by correlation to motor evoked potential monitoring during deep brain stimulation, a surgical procedure causing hardly any brain shift.
  
  
  RESULTS
  Distances to fiber tracks clearly correlated with motor evoked potential thresholds. Tracks based on nTMS had a higher predictive value than tracks based on anatomic motor cortex definition (P < .001 and P = .005, respectively). However, target site, hemisphere, and active electrode contact did not influence this correlation.
  
  
  CONCLUSIONS
  The implementation of tractography based on nTMS increases the accuracy of fiber tracking. Moreover, this combination of methods has the potential to become a supplemental tool for guiding electrode implantation.
authors.affiliation: ‡Departments of Neurosurgery, §Neurology, and ¶Neuroradiology, Goethe University Hospital, Frankfurt, Germany.
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Forster
authors.forename: Alexander Claudius
authors.initials: AC
authors.lastname: Hoecker
authors.forename: Jun-Suk
authors.initials: JS
authors.lastname: Kang
authors.forename: Johanna
authors.initials: J
authors.lastname: Quick
authors.forename: Volker
authors.initials: V
authors.lastname: Seifert
authors.forename: Elke
authors.initials: E
authors.lastname: Hattingen
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hilker
authors.forename: Lutz Martin
authors.initials: LM
authors.lastname: Weise
mesh_terms: D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000503:physiopathology / Q000628:therapy*; D001931:Brain Mapping / Q000379:methods; D046690:Deep Brain Stimulation / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology / Q000601:surgery; D009069:Movement Disorders / Q000601:surgery; D038361:Neuronavigation / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods; D011446:Prospective Studies; D050781:Transcranial Magnetic Stimulation / Q000379:methods*