Cochlear synaptopathy and hidden hearing loss: a scoping review.

Area of Science:

• Audiology
• Neuroscience
• Otoacoustic Emissions

Background:

• Hidden hearing loss (HHL) and cochlear synaptopathy (CS) represent emerging concepts in auditory dysfunction.
• Understanding the precise pathophysiological definitions is crucial for accurate diagnosis and research.

Purpose of the Study:

• To systematically review and identify the pathophysiological definitions used in studies investigating cochlear synaptopathy (CS) and hidden hearing loss (HHL).

Main Methods:

• A comprehensive literature search was conducted across EMBASE, PubMed, CINAHL, and Web of Science.
• Keywords included "Auditory Synaptopathy," "Neuronal Synaptopathy," "Hidden Hearing Loss," combined with "etiology," "causality," or "diagnosis."
• Studies involving human subjects and utilizing behavioral and/or electrophysiological methods were included.

Main Results:

• Out of 49 included articles, 61.2% adopted the cochlear synaptopathy (CS) terminology, while 34.7% used both CS and HHL terms.
• The most frequently investigated conditions associated with CS/HHL were noise exposure and tinnitus.
• Only 4.1% of studies exclusively used the hidden hearing loss (HHL) terminology.

Conclusions:

• The cochlear synaptopathy (CS) terminology is predominantly employed in current research.
• CS definitions consistently refer to the pathophysiological process of deafferentiation between cochlear nerve fibers and inner hair cells.
• This highlights a consensus on the underlying mechanism of CS/HHL.