Facial Nerve Palsy following Mandibular Setback: A Case Report and Review of the Literature

Abstract

Introduction: Mandibular prognathism is a common dentofacial deformity that is often treated with orthognathic surgery (jaw straightening or corrective jaw surgery). The two most common types of operations to correct mandibular prognathism are the mandibular bilateral sagittal split osteotomy (BSSO) and/or the intraoral vertical ramus osteotomy (IVRO). Although there are other surgeries that exist to correct this type of deformity, the BSSO and IVRO are the most commonly used treatment options. The advantages and disadvantages to each of these procedures are generally well documented in the literature. However, facial nerve palsy is an infrequent and less commonly reported complication of these two types of surgeries. We provide a case report of one such instance of total unilateral facial nerve palsy following mandibular BSSO. Materials and Methods: A 20-year-old man with mandibular prognathism underwent mandibular setback surgery via a bilateral mandibular sagittal split osteotomy. His surgery was complicated by a right-sided mandibular buccal plate fracture intraoperatively and a severe unilateral right-sided cranial nerve VII palsy postoperatively. Results: While still admitted to the hospital, the patient was noted to have a right-sided palsy of all branches of the facial nerve. This facial nerve palsy continued to persist on an outpatient basis, although the patient ultimately had full resolution of his right-sided facial nerve palsy at 10 months postoperatively. Conclusions: The complication of facial nerve palsy may be devastating to a patient, especially when the procedure is deemed elective. Although the exact mechanism is unknown, facial nerve palsy secondary to mandibular surgery is most likely related to the close proximity of the field of operation to the anatomy of the facial nerve. This assumption is supported by the lack of documented cases of facial nerve palsy from maxillary orthognathic surgery. Although rare, the authors feel that the risk of facial nerve injury should be discussed with the patient when mandibular surgery is planned.

Facial nerve palsy after orthognathic surgery caused by a hemoclip

“…Recently, Shimada et al [4] reported cases of facial nerve palsy after bilateral sagittal split ramus osteotomy, most of which developed within 3 days after surgery. Several factors can cause facial nerve damage during or after reduction mandibuloplasty, including the compression of nerves by retractors, postoperative edema or hematoma, pressure packing in the retromandibular region, and unusual fractures of the mandible or styloid process [4][5][6][7][8][9]. However, this case suggests that, to avoid facial nerve injury, blinded hemoclips should not be used.…”

Finite element analysis between Hunsuck/Epker and novel modification of Low Z plasty technique of mandibular sagittal split osteotomy

“…2,3 The Hunsuck-Epker (HE) approach requires dissecting muscle attachments and invading into the oral soft tissue up to the lingula area. 2 However, the HE technique has been reported to cause facial nerve disturbance 4,5,6 and increase the potential risk of compromised airways after a mandibular setback procedure on a severe skeletal Class III deformity. 7 Low Z technique was introduced in 2016 8 and recently developed into a novel modification of the 1 Low Z plasty (NM-Low Z) technique 9 at our hospital.…”