Hidden hearing loss: current perspectives and potential therapies

Hidden hearing loss (HHL), an auditory dysfunction that has gained much recent attention, has the hallmarks of speech discrimination and intelligibility deficits with normal or near-normal hearing thresholds. The pathological mechanisms of HHL are complicated and are not yet fully understood. HHL can be resulted from disorders of the central nervous system such as auditory cortex, and/or pathological changes of inner ear. Thus far, 2 pathological phenomena, synaptopathy and auditory nerve demyelination, have been reported as underlying causes of otogenic HHL. Here, we review the clinical and physiological characteristics of HHL as well as the molecular pathological mechanisms of otogenic HHL and aim to allude to potential therapy targets for clinical applications in the future. Key words: auditory; cochlear hair cells; demyelination; hearing loss; hidden hearing loss; Schwann cells; spiral ganglion neurons; synapse; synaptopathy