(0708) Predictors of Facial Nerve Involvement and Outcomes in Combined Temporal Bone and Parotid Surgery

Introduction: In advanced parotid and skin cancer of the external ear or ear canal, parotid surgery is combined with otologic procedures to achieve complete oncologic resection, clear facial nerve (FN) margin, improve access, and/or allow for nerve grafting. The objective of this study was to review our institution’s experience with combined parotidectomy and otologic surgery for oncologic resection and identify risk factors and predictors of FN involvement.

Methods: We performed a retrospective chart review of patients who underwent combined parotidectomy and otologic surgery (mastoidectomy or lateral temporal bone resection (LTBR)) over a 20-year period.

Results: In total, 53 patients were identified who underwent combined parotidectomy and otologic surgery. Of them, 26 patients underwent FN preservation, and 27 underwent FN sacrifice. Of the 27 patients who had FN sacrifice, 25 had an intraoperative positive nerve biopsy, and 4 did not have clear margins at the end of the case. There were higher rates of FN sacrifice among patients with preoperative House Brackmann (HB) Scores of 2 or higher (89.5%) as compared to patients with preoperative HB scores of 1 (22.6%). However, normal preoperative HB score was noted in 29.2% of patients who underwent FN sacrifice. Patients with facial weakness preoperatively had higher probabilities of cancer recurrence (p = 0.034). Preoperative HB scores were predictive of FN sacrifice and involvement (AUC = 0.829 and 0.913, respectively) whereas preoperative imaging was not an effective predictor of FN sacrifice or involvement (AUC = 0.665 and 0.571, respectively).

Conclusions: Preoperative FN exam was the main predictor of facial nerve sacrifice and facial nerve involvement following combined parotidectomy and otologic surgery. Preop imaging investigating FN involvement as well as temporal bone erosion did not predict intraoperative FN involvement. Results indicate the importance of a documented preoperative physical exam in patients undergoing combined parotid and otologic surgery.