False negative intraoperative neuromonitoring alerts during pediatric spinal deformity surgery: the dreaded outcome.

Abstract

Intraoperative neuromonitoring (IONM) reduces postoperative spinal cord dysfunction during pediatric spinal deformity surgery by allowing intraoperative corrective actions. Currently, data on false negative IONM events in this population are limited. The purpose of this study is to describe false negative IONM cases and explore immediate and final outcomes. An institutional neuromonitoring database (November 1992-April 2024) was reviewed to identify patients (0-18 years) who underwent spinal deformity surgery and experienced false negative IONM. The modalities included somatosensory evoked potentials (SSEP), descending neurogenic evoked potentials (DNEP), and transcranial motor-evoked potentials (TcMEP). Out of the 5317 consecutive cases, 16 patients (0.32%) experienced false negative outcomes. Mean age was 14 years (11-16). Five cases (31.3%) had abnormal neurologic status preoperatively, and all 16 patients experienced neurologic decline, postoperatively. Outcomes were stratified by injury level: among spinal cord-level cases with known outcomes (n = 7), 29% achieved complete recovery; 90% of spinal cord-level injuries used SSEP/DNEP and 10% used SSEP/TcMEP. In nerve root-level cases (n = 6), 17% achieved full recovery. Reoperations included three decompressions, two instrumentation removals, and two revisions. At final follow-up, three patients (19%) had complete recovery, five (31%) partial recovery, five (31%) no recovery, and outcomes were unknown in three (19%). This is the largest series of false negative IONM cases in pediatric spinal deformity surgery to date, with 16 false negative outcomes (0.32%) from 5317 consecutive pediatric spinal deformity cases. In worst case scenario only 19% made a complete recovery. Currently, TcMEP and SSEP monitoring is standard of care and when both are used there was only one false negative case, supporting their use over SSEP/DNEP to mitigate the risk of false negative IONM in spinal cord level surgeries.