Evaluation of middle ear pressure and eustachian tube functions in patients with obstructive sleep apnea syndrome

Objective: Recently, the researches about obstructive sleep apnea syndrome (OSAS) is increasing due to its incidence, related diseases and clinical outcomes. The electrophysiological studies that examined the etiopathogenesis of OSAS have already demonstrated an activation loss in pharyngeal dilatator muscle group, especially genioglossus and tensor veli palatini muscles. Therefore, airway obstruction due to loss of muscular tonus in pharyngeal muscles is likely to affect the eustachian tube functions in patients with obstructive sleep apnea syndrome during sleep. Moreover, loss of tensor veli palatini muscle tonus, a unique muscle that has an active role in opening eustachian tube, has been demonstrated in patients with OSAS; thereby, eustachian tube dysfunction and alterations in middle ear pressure may occur. In case of these perturbations, eustachian tube dysfunction are expected to be present more frequently in patients with OSAS than patients without OSAS. Based on these evidences, eustachian tube functions, middle ear ventilation and pressures were evaluated in patients with OSAS in this thesis. The aim of this thesis is to investigate the presence of eustachian tube dysfunction (ETD) and determine the potential relationship between severity of disease andfrequency of ETD and alterations in middle ear pressures in patients with OSAS. Materials and Methods: A hundred and seven patients who volunteered for the study were included into the study. All patients were examined carefully by ENT specialist and also assessed in the Department of Epilepsy and Sleep Disorders. Polysomnography was performed and phases of sleep results were scored manually. Patients were divided into 4 groups according to their polysomnography scores: Group 1: patients without OSAS (AHI [Apnea-hypopnea index]<5, non-OSAS group), Group 2: patients with mild OSAS (AHI=5-15), Group 3: patients with moderate OSAS (AHI=15-30), Group 4: patients with severe OSAS (AHI>30). Then, Automatic Williams Test (ETF1 test), a special technique that is helpful for the detection the ETD, and tympanometric measurements were applied to all patients. Results: Seventy three (68.2%) patients were male and 34 (31.8%) patients were female; and the average age of all cases was 46.47 ± 12.77. The averages of middle ear pressures in Group 1, 2 and 3 were almost similar to each other. However, the average of middle ear pressure in patients with severe OSAS was lower than other groups (p=0.002). According to the ETF1 results; ETD was detected in 25 (36.6%) patients with severe OSAS, 5 (23.8%) patients with moderate OSAS, 6 (33.3%) patients with mild OSAS, 5 (18.5%) patients without OSAS. There was no statistically significant difference between the OSAS groups (mild, moderate, severe) and non-OSAS group (patients without OSAS) according to the frequency of the ETD (x2F=p=0.126ns p>0.05). Eustachian tube dysfunction was more frequently detected in patients with severe OSAS, when compared with the other groups; however, no statistically significant difference was determined between groups (x2F=p=0.091ns p>0.05). Conclusion: This study obviously demonstrated a significantly lower middle ear pressure in patients with severe OSAS which may suggest a dysfunction of eustachian tube which plays a central role in the regulation of the middle ear pressure. Negative impact on eustachian tube functions was shown in cases who had loss of tensor veli palatini muscle tonus in studies evaluating the soft palate muscles tonus in OSAS patients and defect in the regulation of the middle ear pressure may constitute a potential mechanism in physiopathology. Further studies are required to examine the accuracy of this mechanism.