title: A comparison of a commercially made pedicle stimulating probe with a custom-made device: does the commercial device detect pedicle wall breaches more reliably?
abstract: METHODS
  Clinical trial.
  
  
  OBJECTIVE
  To compare the efficacy of a commercially available stimulating pedicle probe with a custom-made probe for the detection of pedicle wall breaches during screw insertion for the surgical correction of scoliosis.
  
  
  BACKGROUND
  Stimulus triggered electromyography has been used to detect small breaches in the walls of the spinal pedicles during pedicle screw insertion. We routinely use a reusable, custom-made clip that can be attached to the screw, pedicle probe, or other instruments. Commercial systems are available in which the instrument is electrically instrumented to deliver current.
  
  
  METHODS
  In five patients (173 pairs of tests), we compared the threshold current required to trigger an electromyographic response during testing of the pedicle. Each track or screw was tested with both the custom-made and the commercial probe and the threshold current recorded.
  
  
  RESULTS
  Both systems were able to detect pedicle wall breaches using triggered electromyography. The threshold current recorded was not significantly different between the two systems (P > 0.1, paired t test) nor was the difference (0.16 mA) clinically significant.
  
  
  CONCLUSIONS
  No difference was found between the thresholds detected with either system. There is however, a significant difference in the costs of the two probe systems.
authors.affiliation: Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Hedden
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Norton
mesh_terms: D000416:Alberta; D001863:Bone Screws; D004576:Electromyography / Q000191:economics / Q000295:instrumentation*; D004867:Equipment Design; D019054:Evoked Potentials, Motor; D005073:Evoked Potentials, Somatosensory; D017721:Hospital Costs; D006801:Humans; D016343:Monitoring, Intraoperative / Q000191:economics / Q000295:instrumentation*; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012044:Regression Analysis; D012600:Scoliosis / Q000503:physiopathology / Q000601:surgery*; D012684:Sensory Thresholds; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation*; D013126:Spinal Nerve Roots / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation