Transient facial nerve palsy following intraoral vertical ramus osteotomy for mandibular setback.

Intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) are two most frequently techniques for treatment of mandibular prognathism. The most common perioperative nervous complications is the injury of inferior alveolar nerve injury leading to postoperative neurosensory disturbance. Seldom, a troublesome postoperative complication is facial palsy. We reported a 43-year-old male who suffered from a postoperative transient facial palsy following IVRO for mandibular setback.

A healthy 43-year-old man underwent bilateral IVRO to correct mandibular prognathism. Under hypotensive anesthesia, a mucosal incision was performed over the ascending ramus of the mandible, extending down anteriorly lateral to the external oblique ridge near the first molar region. For releasing buccal flap tension, temporalis tendon was stripped from the anterior and lateral aspect of the coronoid process. However, it is hard to placement of Bauer sigmoid notch retractor because of the unusually high position of the bilateral sigmoid notches near the zygomatic arches (Fig. 1). During operation, it took a lot of effort to lift the tissue by the Bauer sigmoid notch retractor. It was also not easy to visualize sigmoid notch, and thus superior osteotomy was performed with considerable difficulty. However, the inferior osteotomy of ramus, the separation of both segments, and the 10 mm of mandibular setback were done smoothly. Thirty-two hours following the operation, the patient showed a weakness of facial muscle expression, especially inability to close the right eyelid and mild drooping of right mouth corner. Facial palsy was diagnosed by the neurologist. Treatments of steroids and vitamin B12 were given to the patient for 14 days and a gradual recovery of the right facial expression were found. Six weeks after the operation, facial muscle function was completely restored without residual asymmetry.

Figure 1

Unusually high position of bilateral sigmoid notches (arrows) near the zygomatic arch.

The verbal communication and facial expression are both important functions of the facial nerve. The quality of life is extremely affected after impairment of facial nerve. Facial palsy is a rare and serious complication after mandibular osteotomy for treatment of facial deformity.1, 2, 3 It usually occurs on one side of the face, rarely on both sides of the face affected. de Vries et al. reported that the incidence of facial nerve injury is determined to be 0.26%. Jones and Van Sickels reviewed the facial nerve injuries after intraoral SSROs and proposed the three mechanisms in causing the facial nerve injury: 1) compression of the facial nerve by placement of retractors behind the posterior ramus, 2) fracture of the styloid process with posterior displacement and 3) direct pressure as a result of distal segment setback. Moreover, the postoperative hematoma formation may also play an important role in causing facial nerve injury.

In our case, the possible cause was that facial nerve was compressed by the Bauer sigmoid notch retractor. The higher sigmoid notch is the risk factor for IVRO technique. To avoid the occurrence of postoperative facial palsy, SSRO instead of IVRO was recommended in this situation. Treatment of postoperative facial palsy was based on the severity of symptoms. Steroid is common medication to reduce edema and inflammation in a short time period., Physical therapy is an alternative treatment to stimulate the facial nerve recovery to a normal function.,

Conflicts of interest

We have no conflicts of interest.