The Varieties of Auditory Neuropathy

Abstract

Auditory neuropathy (AN) was initially described as impairment of auditory neural function, with preserved cochlear hair cell function. In this report, 67 patients with audiological and neurophysiological criteria for hearing loss due to auditory neuropathy are described. Reviewing this large body of patients, AN appears to consist of a number of varieties, with different etiologies and sites affected. All varieties share a relatively spared receptor function, and an impaired neural response, with diminished ability to follow fast temporal changes in the stimulus, but different varieties in this general scheme can be distinguished. Analyses of the clinical features indicate that auditory neuropathies vary in several measures including age of onset, presence of peripheral neuropathy, etiology, and behavioral and physiological measures of auditory function. The sites affected along the peripheral auditory pathway may include dysfunction of the outer hair cells, the synapse between hair cell and auditory nerve, and the auditory nerve fibers, with myelin as well as axonal impairments contributing to the disorder.

Neural and receptor cochlear potentials obtained by transtympanic electrocochleography in auditory neuropathy

“…The level of significance was set at p < 0.05 for all tests. Table 1 contains clinical, audiological, and neurological data from the eight AN patients ordered according to etiology which is diverse in AN (Starr et al, 2000). The disorder was genetic in three (#1-3), degenerative in one (#4), immunological in three (#5-7), and congenital in one (#8).…”

Connexin29 Is Highly Expressed in Cochlear Schwann Cells, and It Is Required for the Normal Development and Function of the Auditory Nerve of Mice

“…The preservation of otoacoustic emissions suggests that outer hair cells function normally. Therefore, the sites of cellular disorders are either in the inner hair cells, SG neurons, central auditory centers, or a combination of these sites (Starr et al, 2000). Genetic, as well as toxic and metabolic factors (e.g., anoxia, hyperbilirubinemia), are suspected contributing factors to auditory neuropathy.…”

Selective Inner Hair Cell Loss in Prematurity: A Temporal Bone Study of Infants from a Neonatal Intensive Care Unit

“…Comparison of results from these two tests has revealed that a subset of sensorineural hearing impairments arise despite apparently normal function of the outer hair cells, as implied by intact OAE responses despite absent or greatly attenuated ABRs. This clinical condition has been termed auditory neuropathy (AN;Starr et al 1996Starr et al , 2000, even though it could logically arise from either damage/degeneration of the cochlear nerve or selective damage/degeneration of the inner hair cells, which provide the exclusive synaptic drive to 95% of the cochlear nerve fibers (Spoendlin 1972). Depending on the size and nature of the population sampled, estimates of the prevalence of AN range anywhere from 5% to 15% of those with sensorineural hearing loss (Rance et al 1999;D'Agostino and Austin 2004).…”