A new technique to improve cortical-evoked potentials in spinal cord monitoring

A ratio method of analysis

Robert R. Madigan, A. E. Linton, S. L. Wallace, John Dougherty, M. L. Eisenstadt, L. B. Powers, A. W. Zimmerman

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Systemic effects such as anesthesia, hypotension, hypothermia, and hypoxia affect the cortical evoked responses. We propose, that by sequential stimulation of the median and posterior tibial nerves, and the construction of a ratio from the value of their amplitudes, the systemic effects can be eliminated and thus improve the reliability of the cortical evoked responses. Two groups of scoliosis patients who underwent spinal surgery with instrumentation were analyzed retrospectively. Both groups had spinal cord monitoring using peripheral nerve stimulation and cortical recordings of the somatosensory-evoked response (SER). In Group 1,50 patients were analyzed for changes in posterior tibial nerve response before and after distraction. Wide variability in the response suggested this method to be less reliable in predicting spinal cord conduction deficits. Thirty-eight patients in Group 2 were analyzed using both the median and posterior tibial nerve amplitudes. A ratio of the posterior tibial to median nerve wave amplitude was constructed, thus eliminating any systemic variables. A critical value, alerting the surgeons to possible decreases in spinal cord conduction, was calculated by subtracting one standard deviation from the mean of the postdistraction ratios of the posterior tibial to median nerves (1.20 -.633 =.567).

Original languageEnglish (US)
Pages (from-to)330-335
Number of pages6
JournalSpine
Volume12
Issue number4
DOIs
StatePublished - Jan 1 1987

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Tibial Nerve
Evoked Potentials
Spinal Cord
Median Nerve
Scoliosis
Hypothermia
Peripheral Nerves
Hypotension
Anesthesia

All Science Journal Classification (ASJC) codes

  • Orthopedics and Sports Medicine
  • Clinical Neurology

Cite this

Madigan, R. R., Linton, A. E., Wallace, S. L., Dougherty, J., Eisenstadt, M. L., Powers, L. B., & Zimmerman, A. W. (1987). A new technique to improve cortical-evoked potentials in spinal cord monitoring: A ratio method of analysis. Spine, 12(4), 330-335. https://doi.org/10.1097/00007632-198705000-00004

A new technique to improve cortical-evoked potentials in spinal cord monitoring : A ratio method of analysis. / Madigan, Robert R.; Linton, A. E.; Wallace, S. L.; Dougherty, John; Eisenstadt, M. L.; Powers, L. B.; Zimmerman, A. W.

In: Spine, Vol. 12, No. 4, 01.01.1987, p. 330-335.

Research output: Contribution to journalArticle

Madigan, RR, Linton, AE, Wallace, SL, Dougherty, J, Eisenstadt, ML, Powers, LB & Zimmerman, AW 1987, 'A new technique to improve cortical-evoked potentials in spinal cord monitoring: A ratio method of analysis', Spine, vol. 12, no. 4, pp. 330-335. https://doi.org/10.1097/00007632-198705000-00004
Madigan, Robert R. ; Linton, A. E. ; Wallace, S. L. ; Dougherty, John ; Eisenstadt, M. L. ; Powers, L. B. ; Zimmerman, A. W. / A new technique to improve cortical-evoked potentials in spinal cord monitoring : A ratio method of analysis. In: Spine. 1987 ; Vol. 12, No. 4. pp. 330-335.
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