The auditory system in methyl mercurial intoxication: a neuropathological investigation on 14 autopsy cases in Niigata, Japan.

The auditory system in 14 autopsy cases of methyl mercurial intoxication in Niigata was examined neuropathologically. In addition to degeneration of the transverse temporal gyrus, there was also either significant loss of small myelinated fibers or decrease of large neurons in the cochlear nerve, ventral cochlear nucleus and inferior colliculus. The degree of decrease was higher in acute patients than in the chronic, and was not correlative to the severity of cerebrovascular sclerosis. The hearing impairment in methyl mercurial intoxication may be induced by the combined degeneration of the neurons or nerve fibers of these structures in both acute and chronic patients.