Diagnostic Performance and Clinical Outcomes of Intraoperative Neuromonitoring in Adolescent Idiopathic Scoliosis: A...

Curve-specific risk factors for intraoperative neuromonitoring (IONM) alerts during surgery for adolescent idiopathic scoliosis (AIS) remain unclear.

We identified 5,206 patients with AIS who underwent spinal fusion with multimodal IONM from a prospective database. Alerts were defined as ≥50% amplitude decrease in somatosensory evoked potentials (SSEPs) and/or transcranial motor evoked potentials (TcMEPs), or >10% SSEP latency increase. Demographics, radiographic parameters, surgical variables, triggering events, interventions, and outcomes were compared between the 252 patients with and 4,954 without an alert.

IONM alerts occurred in 5% of patients. Alert rates varied by Lenke classification, with Type-4 curves demonstrating the highest risk (8%; relative risk [RR] = 1.61, 95% confidence interval [CI], 1.15 to 2.24) and Type 5 demonstrating the lowest risk (2%; RR = 0.45, 95% CI, 0.25 to 0.82). Patients with an alert had a larger mean preoperative major Cobb angle (66.7° ± 15.0° versus 56.1° ± 12.1°, p < 0.001) and more frequent use of Ponte osteotomies (79% versus 66%, p < 0.001). Multivariable analysis demonstrated the major Cobb angle to be the leading independent risk factor for alerts (p < 0.001). Hypotension was the leading triggering event (23%), and raising blood pressure was the most common intervention overall (52%). Neurologic deficits occurred in 4% of patients with an alert versus <1% of those without an alert (p < 0.001). Only 12 patients (<1%) experienced neurologic deficits, with 2 having permanent deficits. At 2-year follow-up, the major Cobb angle correction did not differ significantly between the groups with and without alerts, alert status did not independently affect correction (p = 0.058), and the groups achieved similar outcomes (73% versus 71% correction, respectively).

IONM alerts occurred in 5% of patients with AIS and were independently associated with a larger major Cobb angle. Fewer than 1% of patients sustained a permanent neurologic injury, and alerts did not appear to compromise 2-year correction.

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.