Antiviral Prophylaxis and Delayed Facial Nerve Palsy After Schwannoma Surgery

Key Takeaways

• Delayed facial nerve palsy was observed as at least a 2-grade House-Brackmann worsening between postoperative days 5 and 30.
• In the 301-patient cohort, the event occurred in 5%, did not differ significantly by valacyclovir exposure, and was most strongly linked to early House-Brackmann grade III-IV weakness.
• Across pooled data, background incidence was 12.8%, antiviral prophylaxis was associated with lower risk, and most patients recovered to House-Brackmann I-II in a typically self-limited course.

In pooled comparative analyses that included the institutional cohort, antiviral prophylaxis was associated with a relative risk of 0.73 for delayed facial nerve palsy after vestibular schwannoma resection. The analysis combined a single-surgeon retrospective cohort with a systematic review and meta-analysis and focused on a postoperative complication that can emerge after initially stable facial function, rather than on immediate postoperative weakness alone. Together, the data outlined the definition, institutional experience, and pooled comparative findings.

The institutional cohort included 301 vestibular schwannoma resections performed from October 2014 through October 2024. A standardized valacyclovir protocol of 1000 mg three times daily for 7 days, starting 3 days preoperatively, was introduced in June 2015. Delayed facial nerve palsy was defined as at least a 2-grade House-Brackmann worsening between postoperative days 5 and 30. PubMed and Embase were searched in February 2025 under PRISMA guidance, with the analysis centered on that postoperative interval.

Within the single-surgeon cohort, delayed facial nerve palsy occurred in 5% of patients. Rates did not differ significantly between valacyclovir and no-valacyclovir groups, at 6% and 3%, respectively, with P = .42. Early postoperative House-Brackmann grade III-IV emerged as the strongest predictor of later delayed palsy, with an odds ratio of 6.07 and P = .01. In that cohort, early postoperative facial weakness, rather than prophylaxis exposure, showed the clearest association with later delayed palsy.

The systematic review and meta-analysis included 28 studies with 6,835 patients, and adding the cohort brought the total to 7,136. Across those data, the background incidence of delayed facial nerve palsy was 12.8%. Five studies, including the cohort, contributed comparative prophylaxis data and produced a pooled relative risk of 0.73 with antiviral prophylaxis, with a 95% CI of 0.60-0.88 and a number needed to treat of 16. This association was seen in pooled comparative data, not as a significant effect within the cohort alone.

Recovery was generally favorable, with more than 80% of patients returning to House-Brackmann grades I-II regardless of treatment. Delayed facial nerve palsy was characterized as unpredictable but typically self-limited. The authors said pooled data suggest antiviral prophylaxis may meaningfully reduce incidence, while larger prospective studies are still needed for confirmation.