MRI of the pharynx and treatment efficacy of a mandibular advancement device in obstructive sleep apnoea syndrome

In obstructive sleep apnoea syndrome (OSAS), prosthetic mandibular advancement devices (MAD) seem to be a promising treatment alternative to conventional continuous positive airway pressure therapy. Unfortunately, while they are effective in some patients, they are ineffective in others or may even worsen OSAS. At present, it is not known whether predictors can be defined which allow for estimation of the potential effect of oral appliances on the severity of OSAS. Clinical and polysomnographical efficacy of a MAD was evaluated in 15 patients with OSAS. In addition, ultrafast magnetic resonance imaging (MRI) of the pharynx was performed in 13 of these patients at rest during transnasal shallow respiration and during performance of the Muller manoeuvre, both with and without the MAD, and the site of closure was determined. The MAD reduced the mean apnoea/hypopnoea index (AHI) from 19.8+/-14.5 to 7.2+/-7.4(.)h(-1). Seven subjects (53.8%) had at least a 50% reduction in AHI to a value <10(.)h(-1) with the MAD, whereas the MAD was ineffective in six patients. Five of the seven treatment responders had no significant pharyngeal obstruction during the manoeuvre with the device, while all of them had pharyngeal obstruction when not equipped with the device. Four of the sit patients with treatment failure had a single velopharyngeal obstruction and two a combined obstruction of the velo- and glosso-pharynx during the Muller manoeuvre while nearing the device. The results of this study suggest that airway patency during the Muller manoeuvre while wearing a mandibular advancement device may be predictive of the success of obstructive sleep apnoea syndrome treatment with a mandibular advancement device.