Factors Affecting Final Facial Nerve Outcome in Vestibular Schwannoma Surgery

Objective: To determine factors affecting long-term facial nerve outcome of vestibular schwannoma surgery.

Study Design: Retrospective cohort study.

Setting: Tertiary referral center.

Patients: A total of 652 patients with sporadic unilateral vestibular schwannomas were surgically treated.

Outcome Measures: Outcome was assessed using the House-Brackmann (HB) classification at 2 years. Univariate and multivariate analyses were performed to determine the effect of sex, age, tumor size, operative approach, and year of surgery on outcome. Nervus intermedius aberrant regeneration was determined at 3 and 24 months.

Results: Outcomes over the last 6 years for tumors less than 1.5 cm were 95% normal, 100% were satisfactory (HB I–III), and 0% were unsatisfactory (HB IV-VI). For tumors 1.5–2.4 cm in size, 83% were normal, 99% satisfactory, and 1% unsatisfactory. In tumors 2.5–3.4 cm, 68% were normal, 96% satisfactory, and 4% unsatisfactory. For tumors 3.5–4.4 cm, 52% had normal outcome, 80% were satisfactory, and 20% were unsatisfactory. For tumors larger than 4.5 cm, 50% were normal, 72% were satisfactory, and 28% were unsatisfactory.

Tumor size and year of operation were significant predictors of facial nerve outcome. The surgical learning curve was steepest in the first 50 patients. Aberrant regeneration, producing hemifacial spasm, metallic taste, and crocodile tears, has been analyzed and the results presented.

Conclusions: Outcome depends not only on various clinical determinants but also intraoperative technical factors and monitoring. The surgical learning curve may be reduced by proleptic appointments and by “surgical dovetailing” with inexperienced surgeons working alongside more experienced senior colleagues.