Factors predicting post-operative facial nerve function following Retromastoid Vestibular Schwannoma Surgery

Abstract

Introduction:
Facial nerve preservation is a critical outcome measure in vestibular schwannoma surgery. This study aimed to identify factors predicting postoperative facial nerve function following retromastoid microsurgical resection.

Methods:
An analytical study was conducted in 30 patients with unilateral Vestibular Schwannoma undergoing retromastoid resection at Department of Neurosurgery, Bir Hospital, Nepal. Patient’s clinical data, intraoperative details, and FN function status were recorded. Univariate and multivariate analysis by SPSS 20.0 statistical software were performed to evaluate the factors predicting facial function prognosis and its recovery.

Results:

The study included 30 patients (mean age 40.7 years, 56.7% male) with unilateral vestibular schwannomas undergoing retromastoid resection. Most tumors were large (mean size 3.73 cm; 53.3% >4 cm, 70% Koos grade 4). Immediate postoperative facial nerve dysfunction (House Brackmann III-VI) was observed in 76.7% of cases, improving significantly to 83.3% House Brackmann I-II by 6 months. Tumor consistency strongly influenced outcomes: firm/hard tumors had poorer immediate (p=0.001) and delayed (p=0.002) Facial Nerve function compared to soft/cystic tumors. Intraoperative neuromonitoring (used in 20% of cases) improved immediate Facial Nerve outcomes (p=0.001) but showed no long-term benefit (p=0.373). Age ≥30 years predicted worse immediate Facial Nerve function (p=0.012), though this disparity resolved by 6 months (p=0.839). Preoperative Facial Nerve dysfunction correlated with persistent poor outcomes (p=0.0001). Tumor size, extent of resection, and hearing status did not significantly affect Facial Nerve prognosis. One mortality (3.3%) occurred due to postoperative hematoma and hydrocephalus.

Conclusion:
This study highlights the importance of tumor consistency, preoperative nerve status, and surgical technique in predicting facial nerve outcomes. Findings may guide preoperative counseling and surgical planning.