The Influence of Dissection Range of the Facial Nerve on Transient Postoperative Facial Palsy in Mandibular Condyle Fractures

Abstract

Purpose: This study examined the relation between dissection range of facial nerve branches and transient postoperative facial palsy caused by nerve traction for open treatment of mandibular condyle fractures using a preauricular approach. Materials and Methods: This retrospective study included 58 patients who underwent rigid fixation of condylar head and upper neck fractures. Patients were divided into 3 groups based on dissection range of the frontal and zygomatic branches. For group 1(n = 22), the dissection range was extended anteriorly and posteriorly from the condylar borders through the retroparotid approach. The transparotid approach was used in groups 2 (n = 19) and 3 (n = 17) in which nerve dissection was limited to the condylar borders and was extended only anteriorly, respectively. Using multivariate correlation and multiple regression analyses, differences in duration of nerve traction and angle difference by traction from the natural course of the nerve were analyzed according to dissection range, and the recovery period for facial palsy was evaluated. Results: The duration of nerve traction for group 2 was 77.53 minutes, which was longer than that for groups 1 (66.00 minutes) and 3 (65.41 minutes). The angle differences by traction were 62.42 degrees and 58.00 degrees for the frontal and zygomatic branches in group 2, respectively, which were considerably greater than those in groups 1 (23.32 degrees and 20.14 degrees) and 3 (37.24 degrees and 28.88 degrees). In consequence, group 2 showed the longest recovery, requiring 64.47 days for the frontal branch and 51.63 days for the zygomatic branch. The angle difference by traction had a greater influence on the recovery period than duration of nerve traction. Conclusions: Duration of nerve traction and angle difference by traction were quantitatively dependent on the dissection range of facial nerve branches and were related to the recovery period for transient facial palsy. (C) 2018 American Association of Oral and Maxillofacial Surgeons