EVALUATION OF INTRAOPERATIVE SOMATOSENSORY-EVOKED POTENTIAL MONITORING DURING 100 CERVICAL OPERATIONS

Continuous intraoperative somatosensory-evoked potential monitoring du ring 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 m ight play a similar role in cervical surgery, the authors compared the morbidity and mortality rates associated with 218 patients who were n ot monitored and were operated on between 1985-1989 with those found i n 100 consecutive somatosensory-evoked potential monitored procedures done from 1989-1991. The cervical procedures were conducted for disc d isease, stenosis, spondylosis, and ossification of the posterior longi tudinal ligament. Eight of 218 unmonitored patients became quadriplegi c (3.7%) and 1 died (0.5%); no instances of quadriplegia and no deaths were encountered among the 100 monitored patients. The reduction of n eurologic deficit was attributed in part to early somatosensory-evoked potential detection of vascular or mechanical compromise of the spina l cord or nerve roots and to the immediate alteration of anesthetic or surgical technique in response to somatosensory-evoked potential chan ges, i,e., reversal of systemic or ''relative'' hypotension, adjustmen t of operative position, release of distraction, and cessation of mani pulation. Continuous intraoperative somatosensory-evoked potential mon itoring also was a practical tool in monitoring cervical surgery.