Decreased perception of high frequency sound in severe obstructive sleep apnea.

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of upper airway obstruction during sleep, which is manifested by apnea or hypopnea. Decreased blood oxygen saturation, changes in heart rate, fluctuations in brain perfusion, changes in intracranial pressure, snoring and vibration are factors that may potentially affect hearing in patients with OSA. The aim of the present study was to test the hypothesis that hearing is affected in OSA. 43 males aged 34-74 years (mean 48.2) with suspected sleep-disordered breathing without other comorbidity or medication that may affect sleep or hearing were included. Nocturnal polysomnography, pure tone audiometry (PTA), transient evoked otoacoustic emissions (TEOAE) and brainstem auditory evoked potentials (BAEP) were evaluated. The severity of OSA was indicated by the number of apneas and hypopneas per hour of sleep (apnoe/hypopnoe index - AHI). OSA (AHI>/=5) was detected in 28 patients by polysomnography. Mild OSA (AHI 5-15) was confirmed in 11 patients, severe OSA (AHI>/=30) in 17 patients. Simple snoring (AHI<5) was diagnosed in 15 males. In patients suffering from severe OSA, tone audiometry demonstrated higher auditory threshold at frequencies of 4000 and 8000 Hz than in patients with AHI<15 (p<0.005). Auditory threshold values correlated with age in all groups. At a frequency of 8000 Hz, auditory threshold additionally correlated with BMI, AHI, oxygen desaturation index and decreased oxygen saturation. No differences were detected in TEOAE and BAEP between subjects with OSA and snoring. PTA and TEOAE decreased with increasing age. The present results show decreased perception of high frequency sound in severe OSA.