On the other hand, it may be that the AN syndrome is just so imprecise that there is little clinical attention devoted to it and it deserves to remain obscure. Tools to diagnose auditory neuropathy ( otoacousticĮmissions or OAE) is generally little known to any specialty physicians First, the syndrome itself is little known. It is possible (but not very likely) that the medical profession underdiagnoses auditory Otherwise, it would be very puzzling how a disorder of the 8th nerve could selectively damage the auditory portion or vestibular portion as the two parts of the nerve are extremely close and one would think that the same process that damages one would also damage the other. In other words, the vestibular findings of AN may have been largely overlooked. The recently reported "CANVAS" syndrome (cerebellar ataxia, neuropathy, vestibular areflexia) would be a reasonable candidate for this as well. Similarly, there probably is an analogous "vestibular neuropathy" syndrome,Ĭharacterized by absent vestibular evoked potentials ( VEMP tests), and peculiarities in the ENG or rotatory chair test. Of course, these were likely very severe situations. Nash (2014) reported vestibulopathy in 42% of children getting cochlear implants for AN. Sujeet et al (2014) reported that absent VEMP and reduced caloric responses were common in AN patients. This group, lacking the wiring for hearing, would be expected to do very poorly concerning acquisition of hearing.Īuditory neuropathy, when it is truly due to nerve damage, may also affect vestibular function Some reports find cochlear aplasia - a small cochlear nerve or bony aperture for the cochlear nerve (Jeong et al, 2013). See the figure above for Rance/Starr's opinion regarding of the site of lesion. It has been suggested that there are two forms of AN- a "presynaptic" type involving damage to the auditory nerve, and a "postsynaptic" version reflecting damage at the synapse of the cochlear nerve with the cochlear nucleus (Rance and Starr, 2015). We will stick to the term auditory neuropathy herein (AN). (not a good name), auditory neural synchrony disorder, auditory neuropathy, and most recently as auditory neuropathy spectrum disorder. Hearing thresholds and OAE (although with some reduction), this disorder has been referred A related acronym, ANSD - auditory neuropathy spectrum disorder - is a less well defined version of AN.Īs paradoxical findings because of a discrepancy between absent ABR and present Overlap syndrome between otology and neurology, as it causes symptoms of interest to otologists (hearing loss), but is caused by a disease of interest to neurologists (nerve damage). Portion of the eighth nerve (6 on the picture to the left), which is located between the inner ear (cochlea-D)Īnd the brainstem. Schematic from Rance and Starr (2015) defining putative sites for testing pattern defined as "auditory neuropathy"Īn auditory neuropathy (AN) is roughly defined anatomically as a hearing loss caused by damage or aplasia of the auditory The lesion in auditory neuropathy is the nerve (6)
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