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KMID : 0858620080120010001
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Korean Journal of Audiology
2008 Volume.12 No. 1 p.1 ~ p.9
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Auditory Neuropathy
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Kim Lee-Suk
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Abstract
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Auditory neuropathy (AN) is a hearing disorder caused by desynchronous neural discharge of auditory nerve, which is characterized by an absent or severely abnormal auditory brainstem response (ABR), with preservation of cochlear microphonics or otoacoustic emissions (OAE). This finding suggests that outer hair cell is normal but function of inner hair cell or auditory nerve is impaired. The patients with AN show normal to profound hearing loss for pure tone and impaired speech discrimination out of proportion to pure tone loss. Conventional amplification is of little benefit because neural synchrony is not restored by amplification with hearing aid. Frequency-modulation system to enhance signal-to-noise ratio and facilitate lip reading has only modest success. Recently, cochlear implantation has been reported to be successful for rehabilitation of patients with AN, although there has been some exception with poor outcomes. Most patients who received cochlear implantation showed significant improvements in speech perception abilities, and good results in electrical compound action potential and electrical auditory brainstem response were obtained, indicating that synchronous neural discharges can be restored by electrical stimulation introduced by the cochlear implants. Some very young children with AN demonstrate spontaneous hearing improvement or appearance of a normal ABR, and develop speech and language normally without any intervention. Therefore cochlear implantation should be considered after the persistent AN without spontaneous recovery is confirmed through repeated assessment for auditory capacity, speech development and electrophysiological measures including ABR and OAE.
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KEYWORD
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Auditory neuropathy, Auditory brainstem response, Otoacoustic emission, Cochlear implantation
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