A morphological and morphometric study of the peripheral process of the human vestibular nerve following posterior cranial fossa neurectomy

Three vestibular nerve specimens removed at transmeatal neurectomy were stu died in order to understand better retrograde degeneration and regeneration after vestibular neurectomy in the posterior cranial fossa. In two cases t his procedure followed retrolabyrinthine retrosigmoid posterior fossa vesti bular neurectomy. The subjects, three patients with Meniere's disease, were compared with one another and two autopsy controls with no known otologica l problem. The specimens were obtained at the distal end of the internal au ditory canal and transversely sectioned. Many collapsed Schwann cell baseme nt membranes were observed. The ratio of small-diameter nerve fibres increa sed significantly after neurectomy. Onion bulb formation around myelinated nerve fibres with small diameters and Schwann cell proliferation around the soma of vestibular ganglion cells reflected remyelination. We conclude tha t peripheral processes of vestibular nerve fibres can undergo retrograde de generation and subsequent regeneration after transection of the central pro cess.