"Auditory neuropathy": physiologic and pathologic evidence calls for more diagnostic specificity

Area of Science:

• Audiology and Otolaryngology
• Neuroscience
• Medical Diagnostics

Background:

• The term "auditory neuropathy" is increasingly used for children with speech understanding deficits disproportionate to audiogram findings.
• This diagnosis is characterized by recordable otoacoustic emissions/cochlear microphonics and absent/atypical auditory brainstem responses.
• Current usage lacks a clear anatomical basis, leading to diagnostic ambiguity.

Purpose of the Study:

• To critically review the anatomical basis and diagnostic appropriateness of the term "auditory neuropathy."
• To differentiate between peripheral auditory nerve pathologies and central auditory pathway disorders.
• To advocate for more comprehensive audiological evaluations to precisely locate auditory system pathologies.

Main Methods:

• Review of auditory pathway anatomy and definitions of neuropathy (demyelinating, axonal, mixed).
• Analysis of published reports on patients diagnosed with "auditory neuropathy" regarding heterogeneity and investigation depth.
• Electrophysiological review of peripheral neuropathies and deficits in auditory system components.

Main Results:

• The term "auditory neuropathy" is anatomically inaccurate for pathologies outside the spiral ganglion cells or 8th nerve.
• Pathologies affecting the central auditory pathway (brainstem/brain) should not be labeled auditory neuropathy.
• Patients diagnosed with "auditory neuropathy" are highly heterogeneous, with many lacking detailed investigations.

Conclusions:

• A plea for comprehensive audiological evaluations to pinpoint the locus of auditory pathologies.
• Recommend limiting "auditory neuropathy" to pathologies of the spiral ganglion cells or 8th nerve.
• Suggest "neural hearing loss" as a term for pathologies affecting higher auditory pathway levels (brainstem to cortex).