Total facial nerve injury during mandibular distraction osteogenesis

Introduction: Over the last 10-15 years, usage of internal mandibular distraction systems has increased in the pediatric population, particularly for craniofacial syndromes. Mandibular distraction osteogenesis (MDO) has been shown to be effective in avoiding tracheostomy or achieving early decannulation in patients with microretrognathic mandibles in hemifacial microsomia or Pierre Robin sequence. As the frequency of the application of MDO has increased, so has the awareness and management of subsequent complications from the procedure. In this study, we discuss a complication involving paresis and eventual recovery of cranial nerve (CN) VII after the application of an MDO internal device at our institution in two cases. We also review the literature and propose multiple anatomic considerations that can impact more than just the marginal branch of CN VII. Method: This study is a retrospective case study from our institution and a review of the literature. Pubmed was queried for terms singularly and in combination including mandibular distraction osteogenesis, facial nerve, cranial nerve, complications, micrognathia, retrognathia. After reviewing the results, studies discussing complications of MDO that involved CN VII were reviewed and included. Results: In the literature review and our retrospective review, CN VII injuries from MDO vary in their length and timing of onset. Management of this complication depended on the timing of onset and ranged from conservative management to removal of the distraction device. Majority (7/9) of the cases resolved to an eventual HouseBrackmann of 0/6 with conservative measures. Conclusion: Total facial nerve injury in association with MDO, has been scarcely reported, though the facial nerve is at great risk given its intimate location near the mandible particularly in neonates. It is encouraging that though it could be a devastating complication, out of all the cases reported, the large majority resolve with a combination of time and steroids.