title: The reliability of topographic measurements from navigated transcranial magnetic stimulation in healthy volunteers and tumor patients.
abstract: BACKGROUND
  Navigated transcranial magnetic stimulation (nTMS) is increasingly being used for preoperative mapping of the motor cortex. Any new technology should undergo rigorous validation before being widely adopted in routine clinical practice. The aim of this experimental study was to assess the intraexaminer and interexaminer reliability of topographic mapping with nTMS.
  
  
  METHODS
  nTMS mapping of the motor cortex for the first dorsal interosseous (FDI) muscle was performed by an expert and a novice examiner, twice in ten healthy volunteers and once in ten tumor patients. The distances between the centers-of-gravity and hotspots were calculated, as were coefficients of variation. This study also compared orthogonal versus variable orientation of the stimulation coil.
  
  
  RESULTS
  The mean (range) distance between centers-of-gravity for the expert examiner in the test-retest protocol with healthy volunteers was 4.40 (1.86-7.68) mm. The mean (range) distance between centers-of-gravity for the expert vs. novice examiner was 4.89 (2.39-9.22) mm. There were no significant differences in this result between healthy volunteers and tumor patients.
  
  
  CONCLUSIONS
  nTMS is sufficiently reliable for clinical use, but examiners should make efforts to minimize sources of error. The reliability of nTMS in tumor patients appears comparable to healthy subjects.
authors.affiliation: Department of Neurosurgery, Charité University Hospital, Augustenburger Platz 1, 13353, Berlin, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Zdunczyk
authors.forename: Robert
authors.initials: R
authors.lastname: Fleischmann
authors.forename: Juliane
authors.initials: J
authors.lastname: Schulz
authors.forename: Peter
authors.initials: P
authors.lastname: Vajkoczy
authors.forename: Thomas
authors.initials: T
authors.lastname: Picht
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D001932:Brain Neoplasms / Q000473:pathology / Q000628:therapy*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology*; D038361:Neuronavigation / Q000379:methods; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult