Prediction of oral appliance treatment outcome in obstructive sleep apnoea syndrome: a preliminary study

OBJECTIVE

Predictors of treatment outcome of oral appliances (OAs) in patients with obstructive sleep apnoea syndrome (OSAS) are not known. There is a pressing need for simple, clinically useful tools to predict treatment outcome. This study aimed to identify predictors of successful OA therapy for OSAS, including evaluation of pharyngeal morphology, which can be measured during routine examination by an otorhinolaryngologist.

METHODOLOGY

This was a prospective study of 26 OSAS patients treated with OAs. A favourable outcome was obtained in 14 patients (responders) but not in 12 patients (nonresponders). The baseline patient characteristics and polysomnography and rhinopharyngeal findings were analysed.

RESULTS

Body mass index (BMI) was significantly lower in responders versus nonresponders (23.6 ± 2.8 vs. 27.9 ± 4.7 kg/m2; p < 0.05). Pharyngeal morphology, age, sex and nasal resistance did not differ between the groups. Multiple regression analysis showed that BMI was a significant predictor of improvement in the apnoea/hypopnoea index after OA treatment (p < 0.05).

CONCLUSION

Here we demonstrated that BMI is a favourable predictor of OA treatment outcome in OSAS patients. Among the OSAS patients, responders had wider retroglossal spaces than nonresponders.

Differential diagnosis of obstructive sleep apnea syndrome patients and snorers using cephalograms

Severe snoring is thought by many to be an early stage of obstructive sleep apnea syndrome (OSAS), but the anatomical relation between snoring and OSAS, if any, has remained unclear. To compare the morphology of the airway between snorers and OSAS patients for possible similarities, we conducted a cephalometric analysis of Japanese OSAS patients (n=10), habitual snorers (n=10), and non-snoring controls (n=50). There was no significant difference in SNB (the angle formed by the sella, nasion and point B) between OSAS patients and the control subjects. Obstructive sleep apnea syndrome patients tended to have an anteriorly positioned maxilla, and an anteroposterior misalignment between the maxilla and mandible. There was also a tendency toward skeletal openbite. Both OSAS patients and snorers had large tongues and large soft palates, thus causing constriction of the airway with resultant smaller airway diameter and smaller airway surface area. Significant differences between OSAS patients and snorers were found in thickness and length of soft palate surface area, and thickness, length, and position of the hyoid bone. These results suggest that cephalographic measurements may be of considerable use in determining the seriousness of a patient's condition.