Revisiting the Selective Vestibular Neurotomy for Intractable Ménière’s Disease in the Era of Endoscopy and Intraoperative Advanced Neuromonitoring

Background Vestibular neurectomy is considered a quite effective salvage procedure to control intractable vertigo associated with Meniere’s disease while preserving hearing and facial nerve function. However, it is still a potentially very dangerous procedure in terms of mortality and morbidity for, at the end, a benign disease. Popularized by Dandy, with a short bracket with House and Brackmann, this surgical treatment does not seem to have gained wide popularity in the otoneurosurgical community for the technical difficulties in selective identification and sectioning of vestibular nerve while sparing the cochlear and facial nerves. This is why the present gold standard for the treatment of severe vertigo associated to Meniere’s disease is transtympanic gentamicin injection and, regarding the surgical treatment, the extradural endolymphatic sac decompression surgery. With the present preliminary experience, we explored the possibility, thanks to the higher magnification offered by the endoscopic technique and the advanced intraoperative neuromonitoring, to maximize the selective section of the vestibular nerve fibers minimizing, at the same time, surgical complications.

Methods Seven patients with disabling, intractable vertigo associated with Ménière’s disease treated by a combined microendoscopic selective vestibular neurotomy were evaluated. All patients come from a failure of a previous extradural surgical decompression of the endolymphatic sac. Demographics, clinical signs and symptoms, quality of life, thresholds of hearing, and adverse events were documented at baseline, 1 week, 1, 3, 6, 9, and 12 months after surgery.

Results At the maximum present follow-up of 1 year, vertigo disappeared in six of seven patients and improved in the last one. In all cases, intraoperative neurophysiological monitoring and direct stimulation of nervous fibers allowed the selective identification of the facial and cochlear nerve. Furthermore, thanks to the better and higher magnification and visualization provided by endoscopic technique, we were able, after the careful inspection of the cranial nerve VIII, to appreciate a slight difference in color between the superior half (the vestibular nerve being relatively grayer) and the inferior half (the cochlear nerve being relatively whiter), which sometimes helped in demarcating the small sulcus between the two components. Moreover, after the initial partial section of the vestibular nerve by irrigating the field with saline solution, this difference becomes much more demarcated hence better guiding the definitive nerve section. In almost all cases, a fine vessel (arteriole) coursing along the demarcation line between the vestibular and cochlear components was identified by endoscopy while was hardly visible even at the highest magnification microscopic view. No major complications occurred, one case presented skin infection.

Conclusion In our preliminary experience, the modern endoscopic technique and the intraoperative advanced neuromonitoring seem to be able to allow a precise, complete, and very selective vestibular neurotomy, preserving at the same time, the cochlear and facial nerve functions. We believe that the surprisingly quite high success rate is due to the completeness of the vestibular nerve deafferentation of almost all its fibers. The main concern is the duration over the time being the follow-up still quite short.