![]() Some patients report symptoms of other non-auditory peripheral neuropathies, while neurologic dysfunction in other patients is revealed only upon clinical neurological examination. Patients with AN/AD may or may not have other neurological abnormalities, though many patients have either overt or subtle neuropathies outside of the auditory system. Of the above measures, OAEs and the ABR, when used together, offer insight into pre-neural as well as neural function in the auditory system and thus may form the most sensitive combination. Clinical tests that are specifically sensitive to auditory nerve dysfunction are middle ear muscle reflexes (ipsilateral and contralateral), ABR, masking level difference, efferent suppression of OAEs, and to a limited extent, word recognition with an ipsilateral competing noise or message. ![]() Outer hair cell function can be evaluated by measuring otoacoustic emissions (OAEs) and cochlear microphonics. Since AN/AD is characterized by normal outer hair cell function and abnormal function in the region of the inner hair cells and/or auditory nerve, the appropriate auditory tests are those sensitive to cochlear and auditory nerve function. Physiological testing is sensitive to this disorder and useful in correctly identifying AN/AD in patients. Patients with AN/AD display auditory characteristics consistent with normal outer hair cell function and dys-synchronous responses of the VIIIth (vestibulocochlear) nerve. (2000) present a case discussion of evidence for neural asynchrony. (1999) showed that patients with auditory neuropathy primarily demonstrate a timing deficit that is consistent with a lack of neural synchrony Kraus et al. Second, the term auditory neuropathy may lead clinicians to discount cochlear implants as a management option even though, as discussed below, cochlear implants have proven beneficial in auditory neuropathy patients. The possibility of a sensory rather than neural disorder is based on a number of factors including the lack of a Wave I in the electrocochleogram (ECochG) and the auditory brainstem response (ABR), absence of neuropathy in non-auditory systems, and human and animal temporal bones showing specific inner hair cell loss. First, the auditory nerve itself may not be directly affected in all cases. While AN/AD patients are seen in most clinical practices, understanding of the characteristics and variation related to AN/AD remains unclear.īerlin, Hood and Rose (2001) recommended the term auditory dys-synchrony based on two primary underlying reasons. A large body of literature has accumulated worldwide since that time and these patients are believed to comprise approximately 10% of all patients presenting with a severe-profound hearing loss based on auditory brainstem responses (ABR). Auditory Neuropathy/AuditoryDys-synchronyĪuditory neuropathy (AN), auditory neuropathy/dys-synchrony (AN/AD), and auditory neuropathy spectrum disorder (ANSD) are terms used to describe patients––including infants, children and adults––who display auditory characteristics consistent with normal function of portions of the inner ear (normal outer hair cell function) but poor responses from the auditory nerve and brainstem (reflecting pathology of the inner hair cells, synapses, and/or the vestibulocochlear nerve). AN/AD, based on 10 patients from our clinic and research lab as well as our colleagues, was first described in the modern literature by Starr, Picton, Sininger, Hood and Berlin in 1996 (Starr et al., 1996).
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