SOMATOSENSORY-EVOKED AND MOTOR-EVOKED POTENTIAL MONITORING WITHOUT A WAKE-UP TEST DURING IDIOPATHIC SCOLIOSIS SURGERY - AN ACCEPTED STANDARD OF CARE

Study Design. This was a retrospective study of 500 patients undergoin g corrective surgery between 1987 and 1997 for spinal deformity caused by idiopathic scoliosis. Objectives. To report the sensitivity and sp ecificity of somatosensory-evoked and neurogenic motor-evoked potentia ls monitoring and the requirements for an intraoperative wake-up test for all idiopathic scoliosis surgeries at a single institution. Summar y of Background Data. Intraoperative monitoring is recommended for use during corrective spinal surgery. Accepted monitoring standards and r equirements for an intraoperative wake-up test are still debated. Meth ods. The study group consisted of 500 patients undergoing corrective s urgery for idiopathic scoliosis between 1987 and 1997. All patients we re monitored using somatosensory-evoked and neurogenic motor-evoked po tential techniques, using a standard protocol developed at this instit ution. Results. The false-positive rate (significant data change witho ut postoperative neurologic deficit) was 0.014% (n = 7). The true-posi tive rate (degradation of data that met warning criteria, with a corre sponding postoperative neurologic deficit) was 0.004% (n = 2). No fals e-negative results (normal data during with a postoperative neurologic deficit) were seen. The sensitivity of combined somatosensory-evoked and neurogenic motor-evoked potentials data in predicting neurologic s tatus was 98.6%, and the specificity of normal data predicting normal findings in a neurologic examination was 100%. Conclusions. Combined s omatosensory-evoked and neurogenic motor-evoked potentials monitoring during idiopathic scoliosis surgery represents a standard of care that obviates the need for an intraoperative wake-up test when reliable da ta are obtained and maintained.