True Incidence of Marginal Mandibular Nerve Palsy Following Neonatal Mandibular Distraction Osteogenesis.

INTRODUCTION: In children with PRS, MDO is routinely performed to alleviate airway obstruction; however, it involves risk of injury to the MMN. We hypothesize that MMN palsy incidence following MDO, reported at 1-15%, 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 2007 and March 2021 was conducted. Patients who underwent MDO under one 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 ± 4.36mm, average duration of intubation was 6.57 ± 2.37 days, and average time until hardware removal was 111.1 ± 23.6 days. Sixteen patients (29.1%) presented with permanent MMN dysfunction, comprised of 8 patients with bilateral weakness and 8 with unilateral weakness. An additional five patients (9.1%) presented with transient MMN weakness that resolved within a 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 (29.1% permanent, 9.1% transient), which is much greater than previously described.