Outer hair cell cochlear dysfunction in obstructive sleep apnea patients

The relationship between Obstructive sleep apnea (OSA) and hearing dysfunction has not been comprehensively evaluated. Upper airway obstruction with OSA could lead to anatomical changes to the eustachian tube, thus impacting middle ear function. Additionally, recurrent oxygen desaturation during sleep may impact cochlea function. Continuous positive airway pressure (CPAP) is the standard treatment for OSA and may impact auditory function by aerating the eustachian tube.

To investigate peripheral hearing function in OSA patients and assess the impact of CPAP therapy on auditory function.

An observational study was conducted on 91 patients (15 no OSA, 31 mild, 14 moderate and 31 severe OSA) undergoing hearing assessment in the sleep laboratory. The study examined hearing function before sleep, middle ear function during sleep, and the effects of CPAP on hearing function.

Increasing OSA severities appears to be associated with diminished cochlear outer hair cell function, possibly due to hypoxia. However, as increasing AHI was associated with reduce cochlear outer hair cell function at 3000Hz while decrease in SpO₂ was associated with reduced function at 1000Hz and 4000Hz, further investigation is warranted. During sleep, middle ear pressure (MEP) increased in all patients, regardless of OSA severities. CPAP treatment further elevated MEP, proportional to the increase in CPAP pressure, but did not appear to affect other auditory regions.

Patients with OSA may exhibit reduced cochlear hair cell function. The treatment of CPAP increases MEP only. The impact of OSA on central auditory regions will need to be examined.