Abstract
The effects of inner ear abnormality on audibility have been explored since the early 20th century when sound detection measures were first used to define and quantify 'hearing loss'. The development in the 1970s of objective measures of cochlear hair cell function (cochlear microphonics, otoacoustic emissions, summating potentials) and auditory nerve/brainstem activity (auditory brainstem responses) have made it possible to distinguish both synaptic and auditory nerve disorders from sensory receptor loss. This distinction is critically important when considering aetiology and management. In this review we address the clinical and pathophysiological features of auditory neuropathy that distinguish site(s) of dysfunction. We describe the diagnostic criteria for: (i) presynaptic disorders affecting inner hair cells and ribbon synapses; (ii) postsynaptic disorders affecting unmyelinated auditory nerve dendrites; (iii) postsynaptic disorders affecting auditory ganglion cells and their myelinated axons and dendrites; and (iv) central neural pathway disorders affecting the auditory brainstem. We review data and principles to identify treatment options for affected patients and explore their benefits as a function of site of lesion.
Highlights
Neurologists have been well aware of ‘hearing’ impairments affecting the auditory nerve due to infections, neoplasms and hereditary neuropathies (e.g. Friedreich ataxia and Charcot–Marie–Tooth disease) (Spoendlin 1974; Hallpike et al, 1980; Nadol et al, 2001)
We describe the diagnostic criteria for: (i) presynaptic disorders affecting inner hair cells and ribbon synapses; (ii) postsynaptic disorders affecting unmyelinated auditory nerve dendrites; (iii) postsynaptic disorders affecting auditory ganglion cells and their myelinated axons and dendrites; and (iv) central neural pathway disorders affecting the auditory brainstem
In this review we address the clinical and pathophysiological features of auditory neuropathy using audiological, psychoacoustical and electrophysiological measures that distinguish between site(s) of abnormal function along the auditory nerve
Summary
Neurologists have been well aware of ‘hearing’ impairments affecting the auditory nerve due to infections (e.g. lues), neoplasms (e.g. acoustic neuroma, brainstem meningiomas) and hereditary neuropathies (e.g. Friedreich ataxia and Charcot–Marie–Tooth disease) (Spoendlin 1974; Hallpike et al, 1980; Nadol et al, 2001). The typical pattern of objective measures includes: normal summating potentials reflecting normal inner hair cell functions, abnormal compound action potentials reflecting reduced and/or varying time of activation of auditory nerve terminals and absent or abnormal ABRs (Santarelli et al, 2008, 2015a).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
