Facial Nerve and Hearing Outcomes after Vestibular Schwannoma Resection Utilizing the Subperineurial Dissection Technique Versus Extracapsular Dissection Technique

Background: Preservation of facial nerve (FN) function and hearing remain principal goals in microsurgical resection of vestibular schwannoma (VS). The subperineurial dissection plane, as described in recent anatomical studies, may offer superior FN and hearing outcomes compared to traditional extracapsular dissection by safeguarding critical perineurial barriers. This study compares FN and hearing outcomes between these two techniques. Methods: A retrospective review was performed on patients who underwent VS resection over a 13-year period at a tertiary academic center. Dissection plane (subperineurial or extracapsular) was extracted from operative notes. All surgical approaches were included for FN analysis; only patients who underwent retrosigmoid or middle fossa approaches were included in hearing analyses (measured by pure tone average [PTA] and speech reception threshold [SRT]). Good FN function was defined as House-Brackmann (HB) I–III at 12 months or last follow-up. Hearing preservation was assessed by difference (Δ) in PTA and SRT pre- to post-operatively. Statistical comparisons used Wilcoxon rank-sum (continuous) and Fisher’s exact (categorical) tests. Results: Results of surgical technique was analyzed in 109 patients (subperineurial, n=32; extracapsular, n=77). Good FN function outcomes (HB I-III at 12 months postoperatively) were seen in 30 (96.8%) patients who underwent subperineurial dissection (n=31). Good FN function outcomes (HB I-III at 12 months postoperatively) were seen in 49 (77.8%) patients who underwent subperineurial dissection (n=63) (p=0.010). PTA shows significantly better PTA postoperatively in patients who underwent subperineurial tumor dissection (ΔPTA = 7 dB), as compared to those who underwent exracapsular dissection (ΔPTA = 36), (p