Intraoperative Electroneurography (ENoG) of Facial Nerve Conduction during Mandibular Distraction Osteogenesis for Robin Sequence.

Abstract

Mandibular distraction osteogenesis (MDO) is a critical intervention for addressing severe upper airway obstruction in infants with Robin Sequence (RS). Nonetheless, this procedure carries a risk of facial nerve dysfunction (FND), particularly affecting the marginal mandibular nerve (MMN). Since 2019, our group has prospectively monitored real-time facial nerve conduction using electroneurography (ENoG) during MDO procedures. This pilot study evaluates nerve conduction changes and their potential association with postoperative clinically visible FND. Nine infants with RS undergoing MDO from 2019-2024 were randomly selected from a prospectively enrolled cohort. ENoG recorded motor responses from the orbicularis oculi and mentalis muscles. Significant changes were defined as a peak latency increase of ≥10% or an amplitude decrease of ≥60% from baseline. Twenty-five unilateral procedures [osteotomy/placement of hardware (18); hardware removal (6); revision (1)] were analyzed by a certified ENoG technician. Median age at surgery was 11.4 months (IQR 2.4-42.7). Retraction during osteotomy was the surgical step most associated with a significant amplitude decrease in 83.3% of cases, while device activation caused the most frequent peak latency increase in 44.4% of cases. Temporary MMN dysfunction was observed after four procedures (16.0%). Sensitivity/specificity were 17.6%/87.5% while NPV was 84.8%. This prospective pilot study suggests intraoperative risk of MMN injury during MDO is greatest during retraction for osteotomy and device activation. With an NPV of 84.8%, ENoG predicted the absence of postoperative FND when there were no significant conduction changes. Further research is necessary to confirm its diagnostic utility and establish standardized pediatric intraoperative ENoG thresholds.