Application Of Intraoperative Neurophysiological Monitoring In Surgery For Cauda Equina And Conus Medullaris Lesions

Objective To investigate the application of intraoperative neurophysiological monitoring in surgery for cauda equina and conus medullaris lesions.Methods The clinical data of 110 patients with cauda equina and conus medullaris lesions were analyzed retrospectively. Those patients were treated at the Department of Neurosurgery, Anhui Provincial Hospital Affiliated to Anhui Medial University, from March 2009 to April 2013. All lesions were removed microscopiclly under intraoperative neurophysiological monitoring. Somatosensory evoked potential (SEP) and motor evoked potential(MEP) were used for monitoring spinal cord function, electromyography(EMG)was used to detemine the range of defect resection. Follow-up observation were carried out from 1 to 58 months.Results SEP showed abnormal in 17 cases during operation, of these,12 cases had SEP amplitude decreasing of 20%-30%, which was detected by physician. After corresponsive intervention, SEP returned to preoperative levels 10-20min later.5 cases had SEP amplitude decreasing of 50%.After ceasing operation for 30mins,3 cases had SEP recovering below 20%. and the operation continued.2 cases had SEP recovering below 20%,but the SEP amplitude decreasing of 50% again after the continue operation, so ceasing the operation. MEP showed abnormal in 12 cases during operation, of these,10 cases had MEP returning to normal,2 cases did not recover, and had no improve of lower limb muscle strength postoperative. Spontaneous EMG showed abnormal in 57 cases during operation, and returned tonormal after reducing pull, stopping electricity knife and electric coagulation. Stimulated EMG was used to located the nerve roots and determine the safe zone.Of these,16 cases took subtotal resection,because of the closely adhesion of lesion and spinal cord around, protecting the function of spinal cord.92 lesions were removed completely under microscope (83.6%), while 18 lesions were performed partial resection(16.4%). In 1-58 months follow-up,102 patients’neurological function had been improved,4 patients’ neurological function had no change,4 patients’neurological function had exacerbated. The change of those eural electrophysiological monitoring indicators was consistent with the improvement of spinal cord function.Conclusion The clinical symptoms of cauda equina and conus medullaris lesions are not typical, the main show is similar to the symptoms of lumbar degenerative disease. Nerve root pain is the most common symptoms. Surgical resection is the most effective treatment. Intraoperative neurophysiological monitoring has the characteristics of reliable, sensitive and continuous observation. It can real-time monitor the integrity of the neural pathway, define the scope of tumor resection.The combined application of neurophysiological and microsurgical techniques can significantly improve the total resection rate of cauda equina and conus medullaris lesions, maximize the protection of the spinal cord and nerve function, reduce the postoperative complications, and enhance the efficacy and safety of surgery.