The adjunct use of descending neurogenic-evoked potentials when transcranial motor-evoked potentials degrade into warning criteria in pediatric spinal deformity surgery: minimizing false-positive events

Purpose: This studies objective was to evaluate the utility of descending neurogenic-evoked potentials (DNEPs) in the setting of transcranial motor-evoked potentials (TCeMEPs) degradation into warning criteria during pediatric spinal deformity surgery. Methods: An institutional spinal cord monitoring database was queried to identify all primary and revision pediatric spinal deformity cases, < / = 21 years of age performed from 1/2006 to 12/2021, in which TCeMEPs were the primary motor tract assessment modality which degraded into warning criteria, with subsequent initiation of adjunct DNEPs. Results: Fourteen surgical cases (0.42%; 3351 total cases) in fourteen patients met inclusion criteria. Mean age was 13.2 years (7.5–21.3). Diagnoses: syndromic (n = 7), kyphosis (n = 3), congenital (n = 2), and idiopathic (n = 2). Three-column osteotomies (3CO)were done in eight patients. TCeMEPs degraded into warning criteria during screw placement (n = 7), 3CO performance/closure (n = 4), or deformity correction (n = 3). DNEPs were present in all cases of warning-criteria TCeMEPs and one case had degradation of DNEPs. Intraoperative Stagnara wake-up tests were performed in only 2/14 cases, with one transient new neurologic deficit (NND). In this specific scenario, DNEPs sensitivity was 50%, specificity 100%, positive predictive value 100%, and negative predictive value 92% to detect aNND. Conclusion: DNEPs were useful in assessing spinal cord function in the setting of TCeMEP data degradation in complex pediatric deformity surgeries. DNEPs demonstrated a higher specificity and positive predictive value in this clinical setting than TCeMEPs when assessing long-term neurologic function after surgery. Based on this small cohort, DNEPs appear to be a useful adjunct modality to TCeMEPs, in this challenging clinical scenario.