Degeneration of cochlear neurons as seen in the spiral ganglion of man.

A light and electron microscopic study of the spiral ganglion cells of a normal individual, a patient with Meniere's syndrome, and a patient with long-standing unilateral profound deafness was done to evaluate patterns of neural degeneration in the human inner ear. Parametric data for the normal spiral ganglion are presented and compared with the pathologic ganglia. In the ear with Meniere's syndrome, the nuclear area and axonic diameter of spiral ganglion cells were significantly smaller than in the contralateral and the normal ear. This was interpreted as evidence of neuronal degeneration in Meniere's syndrome. In the spiral ganglion of the long-standing deaf ear, there appeared to be selective preservation of large cells with no dendritic processes, contrary to the pattern of degeneration seen in the spiral ganglion of the animal.