The Anatomic Landmark Approach to Extratemporal Facial Nerve Repair in Facial Trauma

Objective In this study, we aimed to examine the topical anatomic landmarks of the facial nerve (facial nerve areas) and their application in cases of extratemporal facial nerve injury in maxillofacial trauma. Materials and methods We analyzed 25 maxillofacial trauma patients with facial paralysis who underwent facial nerve reanimation surgery at the Ho Chi Minh City National Hospital of Odonto-Stomatology. The characteristics of each trauma case, including the mechanism of injury, the length of the facial injury, and the location/position of injury, were recorded. The association of the injured nerves with the trauma characteristics and the external landmarks of the facial danger zones was analyzed. Results The buccal branches had the highest rate of paralysis (22/25 cases), followed by zygomatic branches (15/25), frontal branches (11/25), marginal branches (6/25), and the main trunk (1/25). There were four areas related to the external facial nerve landmarks (facial nerve areas) that helped us find the affected nerves: wounds in Area 1 resulted in frontal branch paralysis in five out of eight cases (62.5%); wounds in Area 2 resulted in zygomatic branch paralysis in 8/13 cases (61.5%) and buccal branch paralysis in 12/12 cases (100%); wounds in Area 3 resulted in marginal branch paralysis in 5/10 cases (50%); and wounds in Area 4 alone resulted in main trunk paralysis in one out of four cases or at least two main branches in three out of four cases. Conclusion Extratemporal facial paralysis after facial trauma can be complex and highly variable, leading to difficulty in finding and repairing facial nerves. Thorough clinical examination and evaluation of trauma characteristics can aid in the identification of facial paralysis and repair. Mapping facial wounds using the four anatomic surface landmarks (Areas 1-4 as outlined in this research) helped us anticipate which branches might be traumatized and estimate the position of the distal and proximal endings to repair the nerves in all cases.