Intraoperative neurophysiologic monitoring in idiopathic scoliosis surgery: a retrospective observational study of new neurologic deficits.

Purpose: Patients with adolescent idiopathic scoliosis undergoing corrective surgery are at risk for iatrogenic spinal cord injury and subsequent new neurologic deficits (NNDs). Intraoperative neurophysiologic monitoring (IONM) has been used to identify spinal cord injury; however, available data showing that IONM leads to improved clinical outcomes are inconclusive. This exploratory study aimed to examine the incidence of NNDs after idiopathic scoliosis surgery in two pediatric institutions in Canada with a focus on IONM use.

Methods: Charts of pediatric patients (10-18 yr) with adolescent idiopathic scoliosis who underwent scoliosis correction surgery were retrospectively identified from the operating room database. Data regarding incidence and severity (mild [isolated sensory deficit] vs severe [any motor deficit]) of NNDs as well as demographic and clinical characteristics were extracted.

Results: Of 547 patients reviewed, 359 (66%) underwent IONM and 186 (34%) underwent wake-up test. Neuromonitoring data were missing in two patients. Total incidence of NNDs was 4.9% (95% confidence interval [CI], 3.1 to 6.8). Compared with the wake-up test, patients undergoing IONM were less likely to develop NNDs (unadjusted odds ratio, 0.39; 95% CI, 0.18 to 0.86; P = 0.02). Nevertheless, subgroup analysis did not reveal a statistical difference in severity of those deficits (mild vs severe) with IONM vs wake-up test. Combined anterior and posterior approach was also significantly associated with increased risk of such deficits.

Conclusion: This exploratory study revealed that IONM was associated with a reduced overall incidence of NNDs in idiopathic scoliosis correction; however, its impact on the severity of those deficits is questionable. As we were unable to adjust for confounding variables, further research is needed to determine the impact of IONM on NNDs.