Cochlear synaptopathy in acquired sensorineural hearing loss: Manifestations and mechanisms.
Level 5 - mechanism / opinion, no new human data
Narrative review of animal models and mechanistic pathways with no original human empirical data.
PubMed 28087419 · doi:10.1016/j.heares.2017.01.003
What was done
This paper reviews structural and functional manifestations as well as potential pathophysiological mechanisms of cochlear synaptopathy resulting from noise exposure, ototoxic drugs, and aging in ears with and without overt audiometric threshold shifts, drawing largely from animal model literature.
What was found
The abstract provides no quantitative data or specific numerical estimates. It reports conceptually that synaptic communication between sensory inner hair cells and subsets of cochlear nerve fibers can be permanently disrupted prior to detectable hair cell loss or clinical audiogram threshold elevation, altering auditory processing and potentially contributing to speech-in-noise deficits, tinnitus, and hyperacusis.
Why it matters
It synthesizes the mechanistic basis for hidden hearing loss, explaining how significant neurodegenerative damage and auditory perceptual deficits can occur despite normal standard clinical hearing tests.
Limits
The review relies primarily on preclinical animal models rather than direct human clinical trial data. The abstract does not report quantitative effect sizes, systematic search methodology, or human prevalence metrics.
Cited by
- supports A standard audiometric threshold test can show normal results even when up to 90% of auditory neurons have been lost.