Spinal Cord Tumor Surgery-Importance of Continuous Intraoperative Neurophysiological Monitoring After Tumor Resection

Study Design. A retrospective clinical analysis of patients operated on for spinal tumors. Objective. To report on the importance of intraoperative neurophysiological monitoring (INM) throughout the entire surgical procedure. Summary of Background Data. Postoperative neurological deterioration, despite unaltered neurophysiological monitoring, has been reported. This might be related to timely restricted monitoring. Thus, the likelihood of alterations in INM from positioning to wound closure was analyzed. Methods. Two hundred three patients (age range, 54.9 +/- 17.4 yr) undergoing intradural tumor removal were sampled in a prospective database and analyzed for the occurrence of alterations in intraoperative somatosensory-and motor-evoked potentials. Results. INM alterations were observed in 47 of 203 (23.2%) patients. These alterations were related to tumor resection in 29 (14.3%) cases, whereas these were unrelated to tumor removal in 18 patients: laminotomy in 5 (2.5%) patients, dura opening in 7 (3.5%) patients, dura closure in 5 (2.5%) patients, and laminoplasty in 1 (0.5%) patient caused INM changes. Conclusion. This study demonstrates that monitoring beyond tumor resection is of essential importance in order to detect all critical phases of surgical procedure and to counteract accordingly.