Severe scoliosis, defined by a Cobb angle exceeding 80°, requires surgical correction and is associated with a high risk of postoperative neurological complications. These complications may be reduced by halo gravity traction (HGT) and neuromonitoring. This study evaluated the outcomes of preoperative and intraoperative multimodal neuromonitoring by somatosensory evoked potential (SSEP) and motor evoked potential (MEP) in patients undergoing HGT before and during spinal surgery for severe idiopathic scoliosis. The secondary objective was to investigate any changes in SSEP associated with traction.

A single-center retrospective review was conducted including all patients who underwent surgery for severe idiopathic scoliosis following HGT. Demographic data were collected. Pre-traction, post-traction, and postoperative Cobb angle corrections were reported. Complications, preoperative and intraoperative neuromonitoring data were recorded.

70 patients with an average age at surgery of 14.4 years were included. The mean postoperative correction rate was 68.79%±7.57. Postoperatively, five deficits were observed, with one being permanent. There were 19 neuromonitoring alerts during surgery (27.14%). One false negative occurred, while 15 alerts did not result in postoperative deficits. Abnormal SSEP before traction or at the beginning of the intervention was associated with an intraoperative alert. SSEP latencies increased, and amplitude decreased between the period before traction was applied and the beginning of the surgery.

Multimodal neuromonitoring by MEP and SSEP presents a high number of alerts with low postoperative deficit. Traction appeared to increase SSEP latencies and decrease amplitudes. However, multimodal monitoring remains a valuable tool for reducing the risk of neurological deficits in severe scoliosis undergoing preoperative HGT.