Facial nerve dysfunction following parotidectomy: role of intraoperative facial nerve monitoring.

PURPOSE: Facial nerve dysfunction (FND) is a frequent and serious parotidectomy outcome. Intraoperative facial nerve monitoring (IFNM) is an increasingly used technique to identify the facial nerve (FN) and minimize its injury. This study aimed to evaluate the determinant factors in the presence and severity of FND after parotidectomy, including IFNM. STUDY DESIGN, SETTING AND METHODS: A total of 48 patients consecutively submitted to parotidectomy between 2005 and 2020 in a tertiary hospital were retrospectively analyzed. The House-Brackmann Scale (HBS) was used to assess the severity of FND. RESULTS: There was a mean age of 54.2 ± 17.8 years, 50% were male. Pleomorphic adenoma (41.7%) and Warthin's tumor (25.0%) were most common. From the 23 patients (47.9%) who developed some degree of FND (HBS score of 3.41 ± 1.53), 19 (82.6%) showed facial movement recovery, with a mean recovery time of 4.78 ± 2.53 months. IFNM was performed in 39.6% of the surgeries. The use of IFNM (p = 0.514), the type of surgery-partial or total parotidectomy-(p = 0.853) and the type of histology-benign or malignant lesion-(p = 0.852) did not significantly influence the presence of FND in the postoperative period. However, in the subgroup of patients who developed FND, the HBS value was significantly lower in cases of benign pathology (p = 0.002) and in patients who underwent IFNM (p = 0.017), denoting a significantly lower severity. CONCLUSION: In the present study, IFNM and the existence of a benign lesion have been shown to be associated with lower severity of FND.