Concepts in Neural Coaptation: Using the Facial Nerve as a Paradigm in Understanding Principles Surrounding Nerve Injury and Repair

Objectives: Individuals with nerve transection face unpredictable outcomes, and microsurgical interventions have variable success. The facial nerve in particular is prone to traumatic transection and leads to debilitating sequelae. Surgeons have used multiple modalities of enhancing nerve regeneration and restoring premorbid functionality. The success of nerve regeneration is predicated on multiple physiologic factors. This article sought to collate the literature on factors influencing nerve damage and repair, using the facial nerve as a paradigm. As such, facial reanimation will also be briefly discussed as it relates to the central theme. Design: A PubMed search was conducted to find articles published on nerve physiology and anatomy, as well as repair. Articles from 1947 to 2013 were studied; however, the preponderance of articles in the study was from the past 15 years to include recent advances. Results: The type and severity of nerve injury, as well as timing of intervention, influence the anatomical and functional outcomes of nerve repair. As there is no uniform solution for all reconstructive challenges, multiple factors must be considered when planning an intervention. Future advances suggest a potential role for engineered nerve conduits in providing a tool for nerve regrowth. Conclusion: Our review has detailed mechanisms of nerve injury, physiology, interventions in nerve repair, and future direction of this expanding field. This review provides a guide for the microsurgeon in factors involved in restorative success.