The relationships between cephalometric parameters and severity of obstructive sleep apnea

Objective: To verify the relationships between cephalometric parameters and apnea hypopnea index (AHI) in snoring patients in Chiang Mai University Hospital.

Methods: Fifty patients who attend ENT snoring clinic, Faculty of Medicine, Chiang Mai University Hospital during 1 October, 2007 to 31 October, 2008 were enrolled. All subsequently underwent overnight polysomnography by SOMNOCHECK(®) V2.04 and lateral cephalometric radiographs.

Results: Of the 50 patients, 78% were men (n=39) and 22% were women (n=11). Ages ranged from 31 to 65 years. Average apnea hypopnea index (AHI)=18.4 ± 18.2 events/h. Body mass index (BMI)=27.2 ± 3.3 kg/m². The mean sella-nasion-subspinale (SNA)=84.1 ± 4.3°. Sella-nasion-supramental (SNB)=81.8 ± 3.4°. Posterior airway space (PAS)=14.9 ± 4.3mm. Distance between mandibular plane and hyoid (MP-H)=27.7 ± 5.6 mm. Distance between posterior nasal spine and tip of soft palate (PNS-P)=42.5 ± 5.4mm. Using Pearson's correlation analysis of BMI, the cephalometric parameters from all subjects with AHI revealed BMI, PAS and MP-H had significant correlation with AHI; p=0.009, p=0.003, and p=0.005, respectively. BMI, MP-H, and PAS were correlated with AHI. The multiple regression model for the effects of BMI, PAS, and MP-H on AHI is AHI=2.090(BMI)-1.953(PAS)+1.1333(MP-H)-40.54.

Conclusion: The model seems to be useful as a screening tool to assess the severity of obstructive sleep apnea in snoring patients.