Cochlear synaptopathy and hidden hearing loss: a scoping review

Purpose: To identify the pathophysiological definitions adopted by studies investigating "cochlear synaptopathy" (CS) and "hidden hearing loss" (HHL). Research strategies: The combination of keywords "Auditory Synaptopathy" or "Neuronal Synaptopathy" or "Hidden Hearing Loss" with "etiology" or "causality" or "diagnosis" was used in the databases EMBASE, Pubmed (MEDLINE), CINAHL (EBSCO), and Web of Science. Selection criteria: Studies that investigated CS or HHL in humans using behavioral and/or electrophysiological procedures were included. Data analysis: Data analysis and extraction were performed with regard to terminology, definitions, and population. Results: 49 articles were included. Of these, 61.2% used the CS terminology, 34.7% used both terms, and 4.1% used HHL. The most-studied conditions were exposure to noise and tinnitus. Conclusion: CS terminology was used in most studies, referring to the pathophysiological process of deafferentiation between the cochlear nerve fibers and inner hair cells.