Nasopharyngoscopic evaluation of oral appliance therapy for obstructive sleep apnoea

This study aimed to explore the effect of mandibular advancement splints (MAS) on upper airway anatomy during wakefulness in obstructive sleep apnoea (OSA). Patients commencing treatment for OSA with MAS were recruited. Response to treatment was defined by a >= 50% reduction in the apnoea/hypopnoea index. Nasopharyngoscopy was performed in the supine position. Nasopharyngoscopy was performed in 18 responders and 17 nonresponders. Mandibular advancement caused an increase in the calibre of the velopharynx (mean +/- SEM +40 +/- 10%), with relatively minor changes occurring in the oropharynx and hypopharynx. An increase in cross-sectional area of the velopharynx with mandibular advancement occurred to a greater extent in responders than nonresponders (+56 +/- 16% versus +22 +/- 13%; p < 0.05). Upper airway collapse during the Muller manoeuvre, relative to the baseline cross-sectional area, was greater in nonresponders than responders in the velopharynx (-94 +/- 4% versus -69 +/- 9%; p < 0.01) and oropharynx (-37 +/- 6% versus -16 +/- 3%; p < 0.01). When the Muller manoeuvre was performed with mandibular advancement, airway collapse was greater in nonresponders than responders in the velopharynx (-80 +/- 11% versus +9 +/- 37%; p < 0.001), oropharynx (-36 +/- 6% versus -20 +/- 5%; p < 0.05) and hypopharynx (-64 +/- 6% versus -42 +/- 6%; p < 0.05). These results indicate that velopharyngeal calibre is modified by MAS treatment and this may be useful for predicting treatment response.