Quantitative study of Scarpa's ganglion and vestibular sense organs in endolymphatic hydrops.

The density of vestibular hair cells and the number of neurons in Scarpa's ganglion were estimated for 11 temporal bones with endolymphatic hydrops. The ten subjects from which these bones were taken all exhibited decreased caloric response (when tested), fluctuating hearing loss, and episodic vertigo. The degeneration of vestibular sense organs was found within the "normal" range for all except one case, which showed total degeneration of the posterior crista ampullaris. Ganglion cell counts in all cases were low. In three of the ten subjects, counts fell below the lowest values seen in a sample of "normal" ears. These three subjects exhibited fluctuating hearing loss and episodic vertigo for more than six years prior to death. In cases of unilateral endolymphatic hydrops there was no significant difference between counts in the affected and unaffected ear. Thus, the apparent ganglion cell degeneration may be due to ear disease other than endolymphatic hydrops.