Effect of Anesthetic Variables on Dermatomal Somatosensory-Evoked Potential Monitoring in Elective Lumbar Spinal Surgery

We studied 108 adult cases of elective lumbar surgery using dermatomal somatosensory-evoked potential (DSEP) monitoring to evaluate its usefulness due to concern over potential neurologic injury during pedicle screw insertion. Both surgeons used all of the necessary precautions required during surgery so that DSEP monitoring was not the "primary," but rather a backup system for operative security. Quality tracings were obtained in 71% of cases; anesthetic difficulties being the major cause of poor monitoring. There were no neurological complications related to pedicle screw insertion. We found that DSEP monitoring was an excellent method to verify intraoperative neurological status, but required a high degree of cooperation between the anesthesiologists, monitoring technician, and surgeons. In today's cost-containment environment, its usefulness is subjected to the expertise of the spine surgeon and the hospital setting.