Hemodynamic Consideration in Intraoperative Neurophysiological Monitoring in Neuromuscular Scoliosis Surgery

OBJECTIVE: To prove the hypothesis that the parameters of intraoperative neurophysiological monitoring (IONM) during will be more deteriorated in neuromuscular scoliosis (NMS) than in adolescent idiopathic scoliosis (AIS). METHODS: This retrospective study reviewed the data of 69 patients (NMS=32, AIS=37) who underwent scoliosis surgery under IONM. The amplitude of motor evoked potentials (MEPs), and the amplitude and the latency of somatosensory evoked potentials (SEPs) were examined. Demographic, preoperative, perioperative and postoperative data were analyzed to determine whether they affected the IONM parameters for each group. RESULTS: Of the items analyzed, the bleeding amount was the only significant risk factor for SEP latency deterioration in the NMS group only. The amplitude of SEP and MEP did not correlate with the hemodynamic parameters. The NMS/AIS ratios of the bleeding-related parameters were higher in the order of bleeding amount/weight (2.62, p<0.01), bleeding amount/body mass index (2.13, p<0.01), and bleeding amount (1.56, p<0.01). This study suggests that SEP latency is more vulnerable than SEP or MEP amplitude in ischemic conditions during scoliosis surgery. CONCLUSION: In NMS patients, it should be considered that the bleeding amount can have a critical effect on intraoperative electrophysiological deterioration.