Effectiveness of intraoperative facial nerve monitoring and risk factors related to postoperative facial nerve paralysis in patients with benign parotid tumors: A 20-year study with 902 patients.

OBJECTIVE: We examined the incidence, risk factors, and recovery time for postoperative facial nerve paralysis in patients with benign parotid tumors and also investigated the usefulness of intraoperative facial nerve monitoring (FNM).

METHODS: Subjects were 902 patients with benign parotid tumors. Univariate and multivariate analyses were conducted for risk factors of postoperative facial nerve paralysis. We investigated the relationship between intraoperative FNM and postoperative facial nerve paralysis, and the recovery time for postoperative facial nerve paralysis according to tumor site.

RESULTS: Postoperative facial nerve paralysis occurred in 179 (19.8%) of 902 patients. Among them, 15.1%, 15.8%, and 37.5% had tumors in the superficial lobe, lower pole, and deep lobe, respectively. Paralysis risk factors were deep tumors, large tumors, long operation times, extensive bleeding, and non-use of FNM. Multivariate analysis determined female patients, deep tumors, and long operation times as significant risk factors, and female patients and deep tumors had an odds ratio of nearly 2. Use of intraoperative FNM resulted in a significantly lower incidence of facial nerve paralysis and was particularly useful in patients with superficial lobe tumors. Time to recovery from facial nerve paralysis was 6 months in 88% of the patients.

CONCLUSION: The incidence of paralysis should be kept as low as possible to enhance the postoperative quality of life of patients. The use of intraoperative FNM significantly lowered the incidence of paralysis in female patients with superficial tumors.