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

Abstract

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).

The effect of obstructive sleep apnea syndrome on the central auditory system

“…Alongside the clinical symptoms such as daytime sleepiness, morning headaches, and memory and concentration loss, OSAS increases the risk of cardiovascular system diseases such as coronary artery disease and hypertension and the risk of CNS disorders such as stroke as a result of deterioration of endocrine and metabolic systems (6,13,14).…”

“…Previously, different researchers conducted studies to investigate the effects of OSAS on the hearing system. In these studies ABR, OAE, and audiometry were used and it was shown that hearing loss can be especially profound in moderate to severe OSAS (6,15).…”

“…However, the location and cause of the auditory pathology in OSAS has not yet been fully elucidated. It is thought that hypoxia/reoxidation episodes that occur in the cochlea following hypoxic periods, which are seen in OSAS, and oxidative stress, endothelial dysfunction, and inflammatory events that are secondary to it may be damaging auditory pathways (6,16). Several studies have suggested that this oxidative stress may cause nerve damage in the hearing system (16)(17)(18).…”

“…The apnea attacks in OSAS can lead to acute ischemic changes in cerebral blood circulation and the cochlea (5,6). The inner ear, cochlea, and acoustic nerve are very sensitive to hypoxia since they receive blood supply from terminal arteries without collateral circulation (7)(8)(9).…”

The Anatomical Relationships of the Tongue with the Body System

“…An altered function of the tongue negatively affects the TMJ; consequently, a dysfunctional TMJ will negatively affect the trigeminocardiac reflexes, altering values such as heart rate (bradycardia) and blood pressure (hypotension) [42]. The morphology and the non-physiological position of the tongue negatively affect renal function, smell and hearing, and the cognitive area [43-45]. The causes are probably related to an incorrect breathing at night connected to tissue deoxygenation.…”