Real-time continuous intraoperative electromyographic and somatosensory evoked potential recordings in spinal surgery: correlation of clinical and electrophysiologic findings in a prospective, consecutive series of 213 cases.

Study Design. Retrospective analysis of a prospectively accrued series of 213 consecutive patients who underwent intraoperative neurophysiologic monitoring with electromyography and somatosensony-evoked potentials during thoracolumbar spine surgery. Objectives. To study the incidence of significant intra-operative electrophysiologic changes and new postoperative neurologic deficits. of Background Data. Continuous intraoperative electromyography and somatosensory-evoked potentials are frequently used in spinal surgery to prevent neural injury. However, only limited data are available on the sensitivity, specificity, and predictive values of intra-operative electrophysiologic changes with regard to the occurrence of new postoperative neurologic deficits. Methods. We examined data on patients who underwent intraoperative monitoring with continuous lower limb electromyography and somatosensory-evoked potentials. The analysis focused on the correlation of intra-operative electrophysiologic changes with the development of new neurologic deficits. RESULTS. A total of 213 patients underwent surgery on a total of 378 levels, 32.4% underwent an instrumented fusion. Significant electromyograph activation was observed in 77.5% of the patients and significant somato-sensory-evoked potential changes in 6.6%. Fourteen patients (6.6%) had new postoperative neurologic symptoms. Of those, all had significant electromyograph activation, but only 4 had significant somatosensory-evoked potential changes, Intraoperative electromyograph activation bad a sensitivity of 100% and a specific ity of 23.7% for the detection of a new postoperative neurologic deficit. Somatosensory-evoked potentials had a sensitivity of 28.6% and specificity of 94.7%. Conclusions. Intraoperative electromyographic activation has a high sensitivity for the detection of a new posstoperative neurologic deficit but a low specifificity. In contrast, somatosensory evoked potentials have low sensitivity but high specificity. Combined intraoperative neurophysiologic monitoring with electromyography and somatosensory-evoked potentials is helpful for predicting and possibly preventing neurologic injury during thoracolumbar spine surgery.