What is the role of evoked potentials (EPs) during surgery?

Updated: Jan 27, 2020
  • Author: Adam B Agranoff, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Because EPs are conducted along the spinal cord, their use has been expanded to the operating room, where they provide valuable information for the spinal surgeon. [29, 30, 31, 32]

In scoliosis surgery, for example, a 0.5% incidence of spinal cord injury has been recorded nationally during the surgery. Spinal cord injury requires that the patient be reanesthetized and the spinal hardware removed. Unfortunately, the damage usually is permanent. With intraoperative use of SSEPs, this risk can be reduced 100-fold. While the patient is asleep and the surgery is progressing, the electromyographer performs repeated SSEP studies. If something happens that interrupts the signal, the electromyographer can inform the surgeon immediately, and ideally the problem can be corrected before permanent injury occurs. [33]

A study by Matsuoka et al indicated that in cervical spine surgery, false-positive results from intraoperative monitoring of muscle motor evoked potentials (EPs) can be reduced by using alarm criteria for both facial motor EPs and muscle motor EPs rather than just the criterion for muscle motor EPs alone. The investigators found that a false positive rate of 6.3% occurred when the facial and muscle alarm criteria were considered together, versus 21.5% when the muscle criterion alone was used. [34]

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