Chest

Chest

Volume 124, Issue 1, July 2003, Pages 212-218
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Clinical Investigations
Sleep and Breathing
Cephalometric Analysis in Obese and Nonobese Patients With Obstructive Sleep Apnea Syndrome

https://doi.org/10.1378/chest.124.1.212Get rights and content

Study objectives

The aims of this study were to comprehensively evaluate the cephalometric features of patients with obstructive sleep apnea syndrome (OSAS), and to elucidate the relationship between cephalometric variables and severity of the apnea-hypopnea index (AHI).

Patients

The study population consisted of 62 male patients with OSAS, classified into 33 obese patients (body mass index [BMI] ≥ 27) and 29 nonobese patients (BMI < 27), and 13 male simple snorers (AHI < 5 events per hour).

Method and measurements

Diagnostic polysomnography and measurements of 22 cephalometric variables were carried out for all patients and simple snorers.

Results

Patients with OSAS in both subgroups showed several significant cephalometric features compared with simple snorers: (1) inferiorly positioned hyoid bone, (2) enlarged soft palate, and (3) reduced upper airway width at soft palate. More extensive and severe soft-tissue enlargements including anteriorly positioned hyoid bone and a longer tongue were found in the obese patients. In the nonobese patients, the anteroposterior distances of the bony nasopharynx and oropharynx were significantly smaller than those of simple snorers and obese patients. Stepwise regression analysis showed that anterior displacement of the hyoid bone and retroposition of the mandible were the dominant overall determinants for AHI in patients with OSAS, and that narrowing of the bony oropharynx and inferior displacement of the hyoid bone were dominant determinants for AHI in nonobese patients. A significant regression model for AHI using cephalometric variables could not be obtained for the obese patients, but the BMI proved to be the most significant determinant.

Conclusion

Characteristics of the craniofacial bony structure such as narrowing of the nasopharynx and oropharynx and enlargement of the soft tissue in the upper airway may be important risk factors for the development of OSAS in nonobese patients. In obese patients, the deposition of adipose tissue in the upper airway may aggravate the severity of OSAS.

Section snippets

Study Population

Sixty-two Japanese male patients with OSAS, consecutively referred to Shinshu University Hospital between April 2000 and December 2001, who recorded AHI ≥ 10 events per hour during an overnight polysomnographic study and who complained of habitual snoring and daytime sleepiness, were recruited for this study. They were classified into two subgroups according to BMI: obese OSAS (BMI ≥ 27, n = 33) and nonobese OSAS (BMI < 27, n = 29).11 Thirteen healthy male simple snorers without daytime

Results

The characteristics of the subjects are presented in Table 1. The obese patients with OSAS were younger and showed more severe AHI and oxygen desaturation compared with nonobese patients with OSAS. All cephalometric variables could be measured in most patients; however, we could not find the hyoid bone on a cephalogram of one obese patient, nor obtain an exact measurement of AW1 for four obese patients and three nonobese patients because of enlarged tonsils. When compared with BMI-matched

Discussion

The segments of upper airway narrowing in the evolution of OSAS have attracted much attention. Since narrowing may be present in various segments of upper airway, knowledge of its location is central to an understanding of the pathogenesis of OSAS.2311 In this study, a comparison with simple snorers showed that obese and nonobese patients with OSAS were commonly characterized by the following craniofacial anatomical features: a longer soft palate, upper airway narrowing at the soft palate, and

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    Copyright © 2003 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.