Multimodal intraoperative neuromonitoring in corrective surgery for adolescent idiopathic scoliosis: Evaluation of 354 consecutive cases

Abstract

Background:Multimodal intraoperative neuromonitoring is recommended during corrective spinal surgery, and has been widely used in surgery for spinal deformity with successful outcomes. Despite successful outcomes of corrective surgery due to increased safety of the patients with the usage of spinal cord monitoring in many large spine centers, this modality has not yet achieved widespread popularity. We report the analysis of prospectively collected intraoperative neurophysiological monitoring data of 354 consecutive patients undergoing corrective surgery for adolescent idiopathic scoliosis (AIS) to establish the efficacy of multimodal neuromonitoring and to evaluate comparative sensitivity and specificity.Materials and Methods:The study group consisted of 354 (female = 309; male = 45) patients undergoing spinal deformity corrective surgery between 2004 and 2008. Patients were monitored using electrophysiological methods including somatosensory-evoked potentials and motor-evoked potentials simultaneously.Results:Mean age of patients was 13.6 years (±2.3 years). The operative procedures involved were instrumented fusion of the thoracic/lumbar/both curves, Baseline somatosensory-evoked potentials (SSEP) and neurogenic motor-evoked potentials (NMEP) were recorded successfully in all cases. Thirteen cases expressed significant alert to prompt reversal of intervention. All these 13 cases with significant alert had detectable NMEP alerts, whereas significant SSEP alert was detected in 8 cases. Two patients awoke with new neurological deficit (0.56%) and had significant intraoperative SSEP + NMEP alerts. There were no false positives with SSEP (high specificity) but 5 patients with false negatives with SSEP (38%) reduced its sensitivity. There was no false negative with NMEP but 2 of 13 cases were false positive with NMEP (15%). The specificity of SSEP (100%) is higher than NMEP (96%); however, the sensitivity of NMEP (100%) is far better than SSEP (51%). Due to these results, the overall sensitivity, specificity and positive predictive value of combined multimodality neuromonitoring in this adult deformity series was 100, 98.5 and 85%, respectively.Conclusion:Neurogenic motor-evoked potential (NMEP) monitoring appears to be superior to conventional SSEP monitoring for identifying evolving spinal cord injury. Used in conjunction, the sensitivity and specificity of combined neuromonitoring may reach up to 100%. Multimodality monitoring with SSEP + NMEP should be the standard of care.

Neuromonitoring changes in pediatric spinal deformity surgery: a single-institution experience

“…They had 13 true neurophysiological alerts (3.7% of 354 cases), with 2 (0.6%) of those 13 demonstrating postoperative neurological deficits. 5 In the largest series to date, Thuet et al reported an incidence of 2.2% true positive IONM changes from a cohort of 3436 pediatric spinal deformity patients. 13 We observed a slightly higher rate of 9.1%, with 0.8% of our patients having new postoperative neurological deficits.…”

“…The differences noted between our series and other previously reported incidences may be partially explained by the variability of neuromonitoring techniques and thresholds considered significant in each series. 4,5,13,15 The true incidence of neural injury as well as the sensitivity and specificity of IONM may also be quite variable due to variations in the definition of true positive findings. The Stagnara wake-up test is often used as the "gold standard" to corroborate IONM changes, but it can contribute to ambiguity, as multiple modifications in management are typically initiated simultaneously at the onset of IONM changes.…”

“…10 Taken together, SSEP and tcMEP monitoring provide exceptionally high sensitivity and specificity for communicating intraoperative changes in the spinal cord. 4,5,9,11,15 Despite the increased use of IONM throughout the field of spinal surgery, there is a paucity of literature related to its use in pediatrics as compared with the spinal surgery in adults. 4,5,15 We present the experience of a single institution with IONM and pediatric spinal deformity surgery and one of the largest reported series of IONM changes to date.…”

Perioperative concerns in pediatric patients undergoing different types of scoliosis correction surgery: A retrospective observational study

“…This can result in a patient developing motor weakness and paraplegia despite a normal SSEP trace. [15] This led to monitoring of the MEPs in the subsequent patients in our series. A combination of MEP and the SSEP monitoring is preferred and planned for future cases as it would help better in detecting inadvertent spinal cord damage.…”

“…A combination of MEP and the SSEP monitoring is preferred and planned for future cases as it would help better in detecting inadvertent spinal cord damage. [15]…”