Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement

Yong bing Shi, Michael Binette, William Martin, James M. Pearson, Robert Hart

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Study Design. Thoracic pedicle screws were stimulated electrically while recording electromyography (EMG) activity in associated muscle groups intraoperatively. Screw position was then evaluated after surgery using computed tomography (CT). The CT results were compared with evoked EMG threshold values. Objective. To report our experience with pedicle screw stimulation in thoracic vertebrae in 22 patients who underwent thoracic level spinal instrumentation from May 1999 to March 2001. Summary of Background Data. Pedicle screw stimulation for intraoperative assessment of screw placement has been reported in lumbosacral spinal procedures. Evoked EMG thresholds 15 mA provide a 98% confidence of accurate screw positioning on postoperative CT scans. Methods. Evoked EMG activity was recorded from ulnar carpal flexors, intercostals, or abdominal muscle groups, depending on the level of screw placement. Postoperative CT scans were read by a staff orthopedic spine surgeon, a senior resident in orthopedics, and a musculoskeletal radiologist. Results. Results of 87 screws are reported. Five screws (5.7%) showed penetration on postoperative CT scans. Six screws (6.9%) had stimulation thresholds ≤11 mA, of which three showed cortical breakthrough. Of the 81 screws with thresholds >11 mA, 79 (97.5%) were within the vertebra. No postoperative neurologic complications were noted in any of the 22 patients. Conclusion. These results are consistent with previous studies of lumbosacral pedicle screws. In this series, stimulation thresholds >11 mA have a 97.5% negative predictive value, suggesting that cortical violation is highly unlikely. Although judgment of screw placement should not depend solely on stimulation thresholds, pedicle screw stimulation may provide rapid and useful intraoperative information on screw placement during procedures involving the use of thoracic pedicle screws.

Original languageEnglish (US)
Pages (from-to)595-601
Number of pages7
JournalSpine
Volume28
Issue number6
DOIs
StatePublished - Mar 15 2003

Fingerprint

Electric Stimulation
Thorax
Electromyography
Tomography
Spine
Intercostal Muscles
Thoracic Vertebrae
Abdominal Muscles
Wrist
Nervous System
Orthopedics
Pedicle Screws
Muscles

Keywords

  • Electromyography
  • Intraoperative neurophysiologic monitoring
  • Pedicle screw stimulation
  • Thoracic pedicle screw

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Orthopedics and Sports Medicine

Cite this

Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement. / Shi, Yong bing; Binette, Michael; Martin, William; Pearson, James M.; Hart, Robert.

In: Spine, Vol. 28, No. 6, 15.03.2003, p. 595-601.

Research output: Contribution to journalArticle

Shi, YB, Binette, M, Martin, W, Pearson, JM & Hart, R 2003, 'Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement', Spine, vol. 28, no. 6, pp. 595-601. https://doi.org/10.1097/00007632-200303150-00015
Shi, Yong bing ; Binette, Michael ; Martin, William ; Pearson, James M. ; Hart, Robert. / Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement. In: Spine. 2003 ; Vol. 28, No. 6. pp. 595-601.
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abstract = "Study Design. Thoracic pedicle screws were stimulated electrically while recording electromyography (EMG) activity in associated muscle groups intraoperatively. Screw position was then evaluated after surgery using computed tomography (CT). The CT results were compared with evoked EMG threshold values. Objective. To report our experience with pedicle screw stimulation in thoracic vertebrae in 22 patients who underwent thoracic level spinal instrumentation from May 1999 to March 2001. Summary of Background Data. Pedicle screw stimulation for intraoperative assessment of screw placement has been reported in lumbosacral spinal procedures. Evoked EMG thresholds 15 mA provide a 98{\%} confidence of accurate screw positioning on postoperative CT scans. Methods. Evoked EMG activity was recorded from ulnar carpal flexors, intercostals, or abdominal muscle groups, depending on the level of screw placement. Postoperative CT scans were read by a staff orthopedic spine surgeon, a senior resident in orthopedics, and a musculoskeletal radiologist. Results. Results of 87 screws are reported. Five screws (5.7{\%}) showed penetration on postoperative CT scans. Six screws (6.9{\%}) had stimulation thresholds ≤11 mA, of which three showed cortical breakthrough. Of the 81 screws with thresholds >11 mA, 79 (97.5{\%}) were within the vertebra. No postoperative neurologic complications were noted in any of the 22 patients. Conclusion. These results are consistent with previous studies of lumbosacral pedicle screws. In this series, stimulation thresholds >11 mA have a 97.5{\%} negative predictive value, suggesting that cortical violation is highly unlikely. Although judgment of screw placement should not depend solely on stimulation thresholds, pedicle screw stimulation may provide rapid and useful intraoperative information on screw placement during procedures involving the use of thoracic pedicle screws.",
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AB - Study Design. Thoracic pedicle screws were stimulated electrically while recording electromyography (EMG) activity in associated muscle groups intraoperatively. Screw position was then evaluated after surgery using computed tomography (CT). The CT results were compared with evoked EMG threshold values. Objective. To report our experience with pedicle screw stimulation in thoracic vertebrae in 22 patients who underwent thoracic level spinal instrumentation from May 1999 to March 2001. Summary of Background Data. Pedicle screw stimulation for intraoperative assessment of screw placement has been reported in lumbosacral spinal procedures. Evoked EMG thresholds 15 mA provide a 98% confidence of accurate screw positioning on postoperative CT scans. Methods. Evoked EMG activity was recorded from ulnar carpal flexors, intercostals, or abdominal muscle groups, depending on the level of screw placement. Postoperative CT scans were read by a staff orthopedic spine surgeon, a senior resident in orthopedics, and a musculoskeletal radiologist. Results. Results of 87 screws are reported. Five screws (5.7%) showed penetration on postoperative CT scans. Six screws (6.9%) had stimulation thresholds ≤11 mA, of which three showed cortical breakthrough. Of the 81 screws with thresholds >11 mA, 79 (97.5%) were within the vertebra. No postoperative neurologic complications were noted in any of the 22 patients. Conclusion. These results are consistent with previous studies of lumbosacral pedicle screws. In this series, stimulation thresholds >11 mA have a 97.5% negative predictive value, suggesting that cortical violation is highly unlikely. Although judgment of screw placement should not depend solely on stimulation thresholds, pedicle screw stimulation may provide rapid and useful intraoperative information on screw placement during procedures involving the use of thoracic pedicle screws.

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