Fully Endoscopic Retrosigmoid Vestibular Nerve Section

Introduction: Long-term control of vertigo in patients with Meniere’s disease requires ablation of vestibular function in the affected ear. Intratympanic injections of vestibuloabaltive drugs offer an effective route of treatment, but this treatment carries a risk of recurrence (10–20%) and a risk of increased hearing loss. Vestibular nerve section has long been the gold standard of hearing preservation vestibuloablative treatments. This presentation details in advances in endoscopic techniques that offer a novel, minimally-invasive method of sectioning the vestibular nerve. These techniques may change the decision analysis for those requiring ablation who wish to avoid possible hearing side effects risk of recurrence and for those patients who have failed intratympanic gentamicin treatment. We describe a fully endoscopic retrosigmoid approach and report pain and symptom control outcomes.

Methods: Retrospective case series and review of technique. The endoscopic procedure consists of a small (1.5 cm × 1.5 cm) retrosigmoid craniectomy with a <1cm dural opening. Following incision of the dura, a 2.7mm outer diameter, zero-degree endoscope is introduced. The cerebellpontine angle is visualized and the eighth cranial nerve identified as it leaves the brainstem. The common vestibular nerve is separated from the cochlear nerve, and it is divided proximal to the fundus of the internal auditory canal. The facial nerve and auditory brainstem responses are monitored throughout the procedure. The dura is closed and the craniectomy is closed with a titanium burr hole cap. Operative and hospital outcomes are reviewed. Subjects completed visual analog pain scales to describe both their immediate and extended post-operative pain. A novel Meniere’s disease specific quality of life survey was also included to evaluate for symptom control.

Results: Six subjects were included for analysis. Operative times and length of stay in the hospital are reported for all subjects. Post-operative dizziness and hearing outcomes are discussed in addition to immediate postoperative and delayed pain scores.

Discussion/Conclusion: With relatively short operative times and length of stay in the hospital, good hearing and vertigo outcomes, and limited pain; fully endoscopic retrosigmoid approach to vestibular nerve section represents a viable option for patients who have failed more conservative measures or who are concerned about hearing loss with chemical vestibular ablation. Dissection and sectioning with only the endoscope for visualization allows for reduction in the craniotomy size and subsequently reduced postoperative pain. It also provides excellent visualization of the anatomy of the cerebellopontine angle.