Changes in the calibre of the upper airway and the surrounding structures after maxillomandibular advancement for obstructive sleep apnoea.

Maxillomandibular advancement (MMA) is effective in the treatment of obstructive sleep apnoea. We aimed to assess changes in the calibre of the upper airway, facial skeleton, and surrounding structural position after MMA and their association with improvement in symptoms. Sixteen consecutive adults with moderate-to-severe apnoea were treated by primary MMA. Polysomnography and computed tomography (CT) of the head and neck were done before and at least 6 months after MMA. The calibre of the upper airway, the facial skeleton, and the surrounding structures were measured with image analysis software. After MMA, patients had a significant reduction in their apnoea-hypopnoea index (31.2 (18.8)number of events (n)/hour (h)). The mean (SD) volume of the airway increased significantly in the velopharynx (p<0.01), oropharynx (p=0.001), and hypopharynx (p<0.001) (by 2.3 (2.4), 2.1 (2.6), and 1.7 (1.1)cm(3), respectively) and the length of the airway was significantly decreased (by 3.1 (3.5)mm p<0.01). The soft palate (p<0.001), tongue (p<0.001), and hyoid (p=0.001) moved significantly anteriorly (by 4.4 (2.0), 7.5 (2.8), and 5.7 (5.0)mm, respectively), and these movements were related to the MMA (r=0.6-0.8). The improvement in the apnoea-hypopnoea index was associated with both maxillary advancement and anterior movements of the soft palate and hyoid (r=0.6-0.7). The results of this study suggest that MMA increases the volume in the upper airway and reduces its length. Improvement in obstructive sleep apnoea is associated with the extent of the anterior movements of the maxilla, soft palate, and hyoid.