Audiologic profile of OSAS and simple snoring patients: the effect of chronic nocturnal intermittent hypoxia on auditory function

The objective of this work was to study the effect of nocturnal intermittent hypoxia on auditory function of simple snoring patients and subjects affected by OSAS; we compared the audiologic profile with the severity of OSAS to detect early signs of cochlear damage. One hundred-sixty patients underwent overnight polysomnography, micro-otoscopy, multi-frequency audiometry, acufenometry, TEOAE recording and d-ROMs test. All subjects were divided in four groups, based on presence/absence of AHI (simple snoring without OSAS, mild OSAS, moderate OSAS, severe OSAS). Sixty (37.5 %) patients were not affected by OSAS, 58 (36.25 %) presented a mild OSAS, 18 (11.25 %) a moderate OSAS and 24 (15 %) a severe OSAS; the 57.14 % of moderate to severe OSAS suffered from tinnitus with respect to the 31.03 % of mild OSAS (P = 0.024). A higher percentage (41.66 %) of hearing loss was found among individuals with moderate to severe degree of OSAS (P < 0.0001). All groups were characterized by a mean hearing threshold <25 dB HL for 0.25–3 kHz frequencies and a progressive decrease in hearing sensitivity, particularly for 6–16 kHz frequencies (P < 0.05). The analysis of otoacoustic emissions SNR mean values evidenced a significant difference between simple snoring and severe OSAS individuals for 3 and 4 kHz frequencies (P < 0.05). d-ROM levels resulted higher in patients with severe OSAS with respect to simple snoring subjects (P = 0.004). Our data underline the key role of chronic nocturnal intermittent hypoxia in the development of an early cochlear damage and a more marked high-frequency hearing loss in case of severe OSAS (P < 0.05).