Evaluation of intraoperative somatosensory-evoked potential monitoring during 100 cervical operations

Continuous intraoperative somatosensory-evoked potential monitoring during scoliosis surgery, along with improved instrumentation techniques, has contributed to the reduction of neurologic injury from 4-6.9% to 0-0.7%. To assess whether somatosensory-evoked potential monitoring might play a similar role in cervical surgery, the authors compared the morbidity and mortality rates associated with 218 patients who were not monitored and were operated on between 1985-1989 with those found in 100 consecutive somatosensory-evoked potential monitored procedures done from 1989-1991. The cervical procedures were conducted for disc disease, stenosis, spondylosis, and ossification of the posterior longitudinal ligament. Eight of 218 unmonitored patients became quadriplegic (3.7%) and 1 died (0.5%); no instances of quadriplegia and no deaths were encountered among the 100 monitored patients. The reduction of neurologic deficit was attributed in part to early somatosensory-evoked potential detection of vascular or mechanical compromise of the spinal cord or nerve roots and to the immediate alteration of anesthetic or surgical technique in response to somatosensory-evoked potential changes, i.e., reversal of systemic or "relative" hypotension, adjustment of operative position, release of distraction, and cessation of manipulation. Continuous intraoperative somatosensory-evoked potential monitoring also was a practical tool in monitoring cervical surgery.