Postparotidectomy facial nerve paralysis: possible etiologic factors and results with routine facial nerve monitoring.

OBJECTIVE: Analyze the incidence and factors responsible for postparotidectomy facial nerve paralysis when the surgery is performed with the routine use of facial nerve monitoring.

STUDY DESIGN: A prospective, nonrandomized study.

METHODS: Seventy consecutive patients underwent parotidectomy with intraoperative facial nerve monitoring. Two devices were used: a custom mechanical transducer and a commercial electromyograph-based apparatus. All patients were analyzed, including those with cancer and those with deliberate or accidental sectioning of facial nerve branches. The outcome variables were the motor facial nerve function according to the House-Brackmann grading scale (HB) at 1 week (temporary paralysis) and 6 to 12 months (definitive paralysis). Facial nerve grading was performed blindly from reviewing videotapes.

RESULTS: The overall incidence of facial paralysis (HB>1) was 27% for temporary and 4% for permanent deficits. Most of the deficits were partial, most often concerning the marginal mandibular branch. Temporary deficits with HB scores of greater than 2 were only present in patients with parotid cancer or infection. Permanent deficits were present in three patients, including one patient with facial nerve sacrifice. Factors significantly associated with an increased incidence of temporary facial paralysis include the extent of parotidectomy, the intraoperative sectioning of facial nerve branches, the histopathology and the size of the lesion, and the duration of the operation.

CONCLUSIONS: Despite a stringent accounting of postoperative facial nerve deficits, these data compare favorably to the literature with or without the use of monitoring. An overall incidence of 27% for temporary facial paralysis and 4% for permanent facial paralysis was found. Although the lack of a control group precludes definitive conclusions on the role of electromyograph-based facial nerve monitoring in routine parotidectomy, the authors found its use very helpful.