Cochlear Synaptopathy in Humans. Review of the Evidence and Future Directions

Cochlear synapthopathy, is a condition where the damage is located at the level of the synapses between IHCs and type-I afferent auditory nerve fibres. The disrupted function of these synapses, either can or can’t be re-established, thus resulting in various signal coding deficits and hearing impairment. Cochlear synaptopathy can be widely present in ears with intact hair cell populations and relatively ‘normal’ audiograms, representing the major cause of “hidden” hearing loss. The present study reviews the major mechanisms involved in hidden hearing loss, emphasizing on future directions regarding appropriate diagnosis of cochlear synaptopathy in humans.