Facial nerve dysfunction after parotidectomy: the role of local factors.

OBJECTIVES/HYPOTHESIS: The objective was to analyze the incidence and factors associated with facial nerve dysfunction after conservative parotidectomy with facial nerve dissection. STUDY DESIGN: A retrospective unicentric study in a tertiary care center with prospective record of studied factors. METHODS: Over a 10-year period, 131 patients with normal facial nerve function underwent a superficial or total conservative parotidectomy with nerve dissection performed by one surgeon for primary benign or malignant tumors. Facial nerve function was assessed on the first postoperative day and at 1 month and 6 months after the parotidectomy. Extent of surgery, histopathological findings, tumor size, close contact of tumor with facial nerve, and sex and age of the patient were reviewed. These variables were studied in a chi2 statistical univariate and stratified analysis to determine their association with postoperative facial nerve dysfunction. RESULTS: Incidence of postoperative facial nerve dysfunction was 42.7% on the first postoperative day, 30.7% at 1 month after the parotidectomy, and 0% at 6 months after the parotidectomy. The most common dysfunction was paresis in a single nerve branch (48.2%), in particular, the marginal mandibular branch. Total parotidectomy was associated with a significantly higher incidence of facial nerve dysfunction during the first postoperative period (60.5% at day 1 and 44.7% at month 1) than superficial parotidectomy (18.2% at day 1 and 10.9% at month 1) (P < .001). In patients with total parotidectomy, close contact of the tumor with the facial nerve was found to have statistical causal relation with facial nerve weakness. In patients with superficial parotidectomy, inflammatory conditions were found as factors that increased postoperative facial nerve dysfunction. CONCLUSION: In the study series of conservative parotidectomies with facial nerve dissection, only extent of surgery and particular local conditions of nerve dissection, especially the close contact of tumor with facial nerve and inflammatory conditions, were found to be associated with postoperative facial nerve dysfunction.