The Effect Of Craniofacial Morphology And Anatomy Of Upper Airway On The Severity Of Obstructive Sleep Apnea

Objective:This study is to value the effects of craniofacial morphology and upper airway anatomy on the severity of obstructive sleep apnea.Methods:A total of 81 patients who were diagnosed with OSA at NHC Key Laboratory of Otorhinolaryngology of Shandong University were randomly selected and enrolled in the research from June 2017 to September 2018,including 75 males and 6 females.According to AHI,the patients were divided into 2 groups:light to moderate group(5<AHI<29.9)and severe group(30<AHI).At the same time,physical examination including the medical history of each subject was performed;and imaging examination(X-ray digital lateral cephalograph radiogragh(LCR)and cone beam CT)was performed in the Department of Radiology at Stomatological Hospital of Shandong University,and Cephalometric Roentgenogram Measurement(CRM)was performed on the obtained LCR by the same examiner;the obtained cone beam CT(CBCT)data was imported into the three-dimensional reconstruction software Dolphin for upper airway reconstruction,and the upper airway and hyoid bone position and soft palate were observed.Finally,the upper airway anatomical structure and the anatomical features of the soft and hard tissues of the craniofacial morphology were compared between 2 groups.Results:l.Correlation Analysis:(1)AHI had a highly negative correlation with LSpO2 and was significantly positively correlated with BMI.(2)MCA,and its transverse diameter and length of soft palate were negatively correlated with AHI(P<0.01),but there was no significant correlation between nasopharyngeal volume pharyngeal volume,total airway volume and AHI.The pharyngeal volume andMCA werepositively correlated with LSpO2.The transverse diameter of MCA had a minus relationship with BMI,and the length of soft palate had a positive relationship with BMI.Correlation between BMI and other upper airway parameters was not observed.(3)There was a positive correlation between the vertical position of hyoid(Hyo-V)and AHI,while other parameters describing maxillofacial morphology were not found to have a relationship with AHI.There was a negative correlation between S-Ar-Go and BMI.The study did not find any relationship between maxillofacial morphology and LSpO2.(4)Go-Pog and Ar-Pog which are representing the length and position of the mandible,had a positive correlation with the total upper airway volume.The length of maxilla(CoA),the length and position of the mandible(CoGn,Go-Pog)had a positive correlation with the nasopharyngeal volume(r>0.3);there was a positive correlation between Go-Pog and MCA;S-Go representing the position of the mandible had a negative correlation with MCA's?transverse diameter;except for S-Ar-Go,the length of cranial base(Ba-N,Ba-S),cranial base angle(N-S-Ar),maxillary length and position(CoA,A-IH),mandible length and position(Go-Pog,Ar-Pog,Pg-H,and Ar-Go-N)had a positive relationship wiht MCA's anteroposterior diameter;maxillary length and sagittal position(CoA,A-H)were positively correlated with thickness of soft palate;mandible length and position(CoGn,S-Go),sagittal position of hyoid bone(Hyo-H)was positively correlated with the inclination of soft palate;the vertical position(Hyo-V)had a positive correlation with the length of soft palate.2.Significance Test of Difference:(1)Both BMI and LSpO2 were significantly different in OSA with different severity.(2)There were statistically significant difference of the total upper airway volume,nasopharyngeal volume,MCA and its transverse dimater,length of soft palate,and vertical position of the hyoid bone between the two groups(P<0.05);The volume,area and diameter of the airway showed significantly smaller in severe group than those of the mild to moderate group.Patients with severe OSA had a larger soft palate,and a lower hyoid bone.(3)The mean volume of pharyngeal volume,MCA and its transverse diameter were significantly lower in obese patients with OSA(P<0.05).Conclusions:1.The upper airway anatomy was affected by the craniofacial morphology.OSA patients with shorter dimension of the maxillary and mandibular length,or maxillo-mandibular retrognathia had a decreased upper airway volume,MCA and its transverse diameter.When the mandible was rotated clockwise,both the oropharynx volume and sagittal diameter were small.2.The upper airway anatomy had an effect on the severity of OSA.Severe OSA patient had a smaller total airway volume,a smaller MCA of the upper airway,and a smaller transverse diameter.The MCA of the upper airway could be used as a predictor of OSA and its severity.3.The study did not find a clear influence of craniofacial morphology on the severity of OSA.Patients with severe OSA was more likely to have a lower hyoid bone,and a larger soft palate.4.The study confirmed that BMI had a greater impact on the severity of OSA,but differences in craniofacial morphology was not observed in OSA patients with different BMI.