# Bicentric analysis of repeated retrosigmoid approach for recurrent vestibular schwannoma: facial nerve function and risk of second recurrence

## TL;DR

This study examines repeated surgery for recurrent acoustic neuroma, finding that shorter intervals between surgeries increase facial nerve risks, while more complete tumor removal reduces recurrence.

## Contribution

Identifies specific risk factors for facial nerve damage and tumor recurrence after repeated retrosigmoid surgery for recurrent vestibular schwannoma.

## Key findings

- 31.4% of patients experienced facial nerve deterioration within 3 months after repeated surgery.
- A shorter interval between surgeries (under 102 months) predicts higher facial nerve risk.
- An extent of resection above 62% during surgery significantly reduces the risk of second recurrence.

## Abstract

Surgical retreatment of recurrent vestibular schwannoma (VS) remains challenging, particularly in balancing tumor control with facial nerve (FN) preservation. This bicentric study aimed to evaluate facial nerve outcomes and risk factors for second recurrence following repeated retrosigmoid craniotomy.

We retrospectively analyzed 35 patients with sporadic VS who underwent repeated retrosigmoid surgery for recurrent VS between 2002 and 2024. Facial nerve function was assessed using the House-Brackmann (HB) grading. Predictors of postoperative FN deterioration at 3-months after repeated surgery and second recurrence were evaluated.

FN deterioration occurred in 11 patients (31.4%) at 3-months after repeated surgery. The time between primary and repeated surgery was significantly shorter in patients with postoperative FN deterioration (mean 42.4 vs. 81.2 months, p = 0.008). ROC analysis identified a cut-off of 102 months (AUC = 0.61; 95% CI: 0.42–0.79) for predicting facial nerve preservation. Regarding tumor control, a second recurrence was observed in 4 patients (11.4%). The volumetric extent of resection (EoR) during repeated surgery was significantly associated with second recurrence (p = 0.011). ROC analysis revealed a critical EoR cut-off of 62.0% (AUC = 0.96; 95% CI: 0.89–1.00), with 100% sensitivity and 92.9% specificity. Adjuvant radiotherapy after incomplete resection was not significantly associated with reduced re-recurrence (p = 0.77).

Repeated retrosigmoid surgery for recurrent VS offers favorable tumor control with acceptable facial nerve outcomes. More aggressive VSs with shorter intervals between surgeries may increase the risk of facial nerve deterioration. Local repeated surgery appears to be of importance regarding further tumor control.

The online version contains supplementary material available at 10.1007/s11060-026-05535-1.