Clinical factors associated with postoperative facial nerve palsy in meningiomas extending into the internal auditory canal.

OBJECTIVE: Meningiomas extending into the internal auditory canal (IAC) are located close to the facial-vestibulocochlear nerve complex and carry a risk of postoperative facial nerve palsy (FP). However, factors associated with postoperative FP in this subgroup remain unclear. This study aimed to identify preoperative factors associated with postoperative FP in patients with meningiomas extending into the IAC. METHODS: We retrospectively reviewed 26 consecutive patients who underwent surgery for posterior fossa meningiomas with tumor extension into the IAC at our institution between January 2017 and June 2025. Clinical, radiological, pathological, and surgical factors were analyzed to identify factors associated with postoperative FP. Postoperative FP was defined as newly developed FP within 24 hours after surgery or deterioration of preexisting FP. RESULTS: Postoperative FP occurred in 5 of 26 patients (19%). All cases were mild to moderate, and persistent FP was observed in only 1 patient (3.8%). Preoperative FP was significantly associated with postoperative FP (2/5 [40%] vs. 0/21 [0%], p = 0.031). Preoperative hearing impairment was also significantly more frequent in the FP group than in the non-FP group (4/5 [80%] vs. 5/21 [24%], p = 0.034). Tumor size, the tumor-IAC relationship, extent of IAC extension, and surgical approach were not associated with postoperative FP. CONCLUSIONS: In patients with meningiomas extending into the IAC, preoperative FP and preoperative hearing impairment were associated with postoperative FP. Preoperative functional impairment of the facial-vestibulocochlear nerve complex may help identify patients who require careful preoperative counseling and nerve-sparing surgical strategies.