The morphology of the vestibular nerve in a patient with normal vestibular function and in patients with Ménière's disease.

The morphology of the vestibular nerve was studied in three fresh nerve specimens obtained by surgery from two patients with Ménière's disease and one patient with tinnitus after an attack of sudden deafness. The number of nerve fibres appeared light microscopically normal. The vestibular ganglion cells of the Ménière-specimens showed, as a characteristic finding advanced vesiculation of the cytoplasm. This change was confirmed by electron microscopy and the vacuoles appeared to consist of widened endoplasmic reticulum cisternae. Numerous primary lysosomes and lipofuscin granules were observed in all vestibular ganglion cells but their number appeared increased in the specimens from Ménière-patients. Some of the vestibular ganglion cells of these patients showed a filamentous appearance and the number of glycogen granules seemed reduced in all of them. All vestibular ganglion cells observed were unmyelinated. The degenerative changes observed might explain the typical elevation of the threshold for vestibular stimulation in Ménière's disease.