Fully endoscopic retrosigmoid keyhole approach versus traditional microscopic microsurgery for small-to-medium vestibular schwannomas: a retrospective matched-cohort study.

BACKGROUND

The surgical management of vestibular schwannoma (VS) has shifted focus from mortality reduction to functional preservation and quality of life. While the traditional microscopic retrosigmoid approach is the gold standard, it suffers from line-of-sight limitations, particularly when visualizing the fundus of the internal acoustic canal (IAC). The fully endoscopic sigmoid sinus keyhole approach (FEE) offers superior visualization and reduced invasiveness; however, current literature lacks rigorous, matched-cohort studies comparing its efficacy and safety against the established microscopic technique.

OBJECTIVE

This study aimed to detail the surgical technique of the fully endoscopic sigmoid sinus keyhole approach and to objectively compare its perioperative outcomes, tumor resection rates, facial and cochlear nerve preservation, and complication rates with those of the traditional microscopic approach (MS) in patients with small-to-medium vestibular schwannomas.

METHODS

A single-center, retrospective matched-cohort study was conducted involving patients treated between June 2023 and June 2025. Thirty-four patients who underwent FEE for Koos Grade I-III vestibular schwannomas were matched 1:1 with 34 control patients undergoing the microscopic approach (MS) based on tumor size, age, and preoperative facial function. Clinical data, including operative time, estimated blood loss, bone window size, extent of resection, House-Brackmann (H-B) grades, hearing preservation, and postoperative complications, were analyzed.

RESULTS

The FEE group demonstrated a significantly smaller bone window area (2.5 ± 0.5 cm² vs. 7.8 ± 1.2 cm², P < 0.001) and significantly lower postoperative headache scores (VAS) compared to the MS group. There were no statistically significant differences between the two groups regarding operative time, blood loss, or hospital stay. Gross total resection rates were comparable (94.1% in FEE vs. 91.2% in MS). Postoperative facial nerve function preservation (H-B Grade I-II) at 1 year was 91.2% in the FEE group and 88.2% in the MS group (P > 0.05). Complication rates, including cerebrospinal fluid leakage and intracranial infection, were similar between groups.

CONCLUSION

The fully endoscopic sigmoid sinus keyhole approach is a safe and effective minimally invasive technique for the resection of small-to-medium vestibular schwannomas. It achieves gross total resection rates and functional preservation rates comparable to the traditional microscopic approach while offering the distinct advantages of a smaller craniotomy and reduced postoperative headache. This technique represents a viable alternative for optimizing early patient recovery and quality of life.