True Incidence of Marginal Mandibular Nerve Palsy following Neonatal Mandibular Distraction Osteogenesis

Background: In children with Pierre Robin sequence (PRS), mandibular distraction osteogenesis (MDO) is routinely performed to alleviate airway obstruction; however, it involves risk of injury to the marginal mandibular nerve (MMN). The authors hypothesize that MMN palsy incidence following MDO, reported at 1% to 15%, is underestimated. This study investigates the true incidence of MMN palsy after MDO to better guide follow-up care and improve treatment of this complication. Methods: A retrospective review of PRS patients who underwent MDO at a single, tertiary pediatric hospital between September of 2007 and March of 2021 was conducted. Patients who underwent MDO younger than 1 year of age and had postoperative clinical evaluations detailing MMN function were included. Logistic regression analysis was performed to investigate predictors of MMN injury. Results: Of 93 patients who underwent MDO, 59.1% met inclusion criteria, 56.4% were female, 43.6% were syndromic, and average age at MDO was 1.52 ± 2.04 months. The average length of mandibular distraction was 17.3 ± 4.36 mm, the average duration of intubation was 6.57 ± 2.37 days, and the average time until hardware removal was 111.1 ± 23.6 days. Sixteen patients (29.1%) presented with permanent MMN dysfunction, consisting of 8 patients with bilateral weakness and 8 with unilateral weakness. An additional 5 patients (9.1%) presented with transient MMN weakness that resolved within 1 year. Average length of follow-up postoperatively was 6.02 years, and no significant predictors of nerve injury were found. Conclusion: In this 14-year review of patients with PRS who underwent MDO, 38.2% demonstrated evidence of MMN palsy (permanent, 29.1%; transient, 9.1%), which is much greater than previously described. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.