title: Movement Along the Spine Induced by Transcranial Electrical Stimulation Related Electrode Positioning.
abstract: METHODS
  A prospective, nonrandomized cohort study.
  
  
  OBJECTIVE
  To describe a technique quantifying movement induced by transcranial electrical stimulation (TES) induced movement in relation to the positioning of electrodes during spinal deformity surgery.
  
  
  BACKGROUND
  TES induced movement may cause injuries and delay surgical procedures. When TES movements are evoked, muscles other than those being monitored any adjustments in stimulation protocols and electrode positioning may be expected to minimize movement whereas preserving quality of monitoring. In this study, seismic evoked responses (SER) induced through TES were studied at different electrode positions.
  
  
  METHODS
  Intraoperative TES-motor evoked potentials were carried out in 12 patients undergoing corrective spine surgery. Accelerometer transducers recorded SER in two directions at four different locations of the spine for TES-electrode montage groups Cz-Fz and C3-C4. A paired t test was used to compare the means of SER and the relationship between movement and TES electrode positioning.
  
  
  RESULTS
  SERs were strongest in the upper body. All mean SERs values for the Cz-Fz group were up to five times larger when compared with the C3-C4 group. However, there were no differences between the C3-C4 and Cz-Fz groups in the lower body locations. Both electrode montage groups showed a gradual stepwise reduction in all mean SER values along the spine from the cranial to caudal region. For the upper body locations, there were no significant associations between SER and both montages; in contrast, a significant association SER was demonstrated in the lumbar region.
  
  
  CONCLUSIONS
  At supramaximum levels, movements resulting from multipulse TES are likely caused by relatively strong contractions from muscles in the neck resulting from direct extracranial stimulation. When interchanging electrode montages in individual cases, the movement in the neck may become reduced. At lumbar levels transcranial evoked muscle contractions dominate movement in the surgically exposed areas.
  
  
  METHODS
  4.
authors.affiliation: Departments of Orthopedics, Amphia Hospital, Breda, The Netherlands.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoebink
authors.affiliation: Orthopedics Sint Maartenskliniek, Nijmegen, The Netherlands.|Department of Neurosurgery, University Medical Center, Groningen, The Netherlands.
authors.forename: Henricus L
authors.initials: HL
authors.lastname: Journée
authors.affiliation: Orthopedics Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: Marinus
authors.initials: M
authors.lastname: de Kleuver
authors.affiliation: Orthopedics Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: Hanneke
authors.initials: H
authors.lastname: Berends
authors.affiliation: Orthopedics Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: Ilona
authors.initials: I
authors.lastname: Racz
authors.affiliation: Department of Orthopedics, Ziekenhuis Rivierenland Tiel, The Netherlands.
authors.forename: Chantal
authors.initials: C
authors.lastname: van Hal
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004566:Electrodes; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods; D009068:Movement / Q000502:physiology*; D056888:Patient Positioning; D011446:Prospective Studies; D013122:Spinal Diseases / Q000628:therapy*; D065908:Transcranial Direct Current Stimulation / Q000379:methods; D055815:Young Adult