Analysis On The Plane And Mechanism Of Tongue Originated Obstruction In OSAHS With Hypertrophic Tongue

Objective: To investigate the plane and its related mechanism of tongue originated obstuction in obstructive sleep apnea hypopnea syndrome(OSAHS)patients with hypertrophic tongue utilizing pharyngeal magnetic resonance imaging(MRI)in combination with upper airway pressure monitoring.It is to propose a targeted treatment plan to improve the effectiveness of the operation.Methods: Nineteen OSAHS patients with hypertrophic tongue and 19 healthy from2017 to 2019 in First Affiliated Hospital of Fujian Medical University were enrolled in this study.Every case was examined by pharyngeal MRI and polysomnography(PSG).The minimum space of the retropalatal space,the minimum space of the retrolingual space,soft palate thickness and the minimum space from the dorsal tongue to the soft palate were measured on the midsagittal plane image.Upper airway pressure monitoring was measured only in OSAHS group.The differences of results between groups were statistically analyzed.Results: 1.Both upper airway pressure monitoring and pharyngeal MRI indicated that the obstruction plane present in patients with OSAHS was mainly velopharyngeal plane.2.The minimum space of the retropalatal space,the radio of the minimum space of the retropalatal space to the minimum space of the retropalatal space:the mean value in OSAHS group(0.36[0.21,0.42],0.26[0.22,0.47])were significant smaller than that of control group(0.53[0.46,0.71],0.62[0.39,0.68]),and the difference was significan(P<0.05).3.The minimum space of the retrolingual space:the mean value in OSAHS group(1.12[0.76,1.37])and control group(1.07[0.80,1.32])were no significant difference in two groups(P>0.05).4.Within two groups,the minimum space of the retropalatal space was both smaller than the minimum space of the retrolingual space,and the difference was significant(P<0.05).5.The minimum space of the retropalatal space:the value in both groups was close to 0,showing no significant difference(P>0.05).6.Soft palate thickness:the mean value in OSAHS group(0.98[0.88,1.12])and control group(0.91[0.84,1.03])were no significant difference in two groups(P>0.05).Conclusions: 1.The velopharyngeal plane was the most common site to develop obstruction in OSAHS patients with hypertrophic tongue,but not the glossopharyngeal plane.2.Its related mechanism may be the backward movement of the soft palate caused by the high arch and the fall of the middle part of hypertrophic tongue.3.It may be a normal physiological phenomenon that retropalatal space is smaller than retrolingual space,which may also be one of the reasons why OSAHS patients are prone to be obstruction in velopharyngeal plane.4.The contact between the back of the tongue and the soft palate may be also a normal physiological phenomenon,but retropalatal space does not narrow in normal people,which may be one of the important mechanisms of "nose breathing" rather than "mouth breathing" during supine sleep in the normal.