Altered inspiratory airway dilation patterns with mandibular advancement splints may help predict treatment outcomes

Introduction : Mandibular advancement increases the lateral dimensions of the nasopharynx via a direct connection between the lateral upper airway and the ramus of the mandible (Brown et al. Sleep 2013; 36:397–404). The aim of this study was to investigate whether a tendinous lateral connection influences the mechanical properties of the lateral walls, airway dimensions and treatment response. Methods : Detailed pharyngeal MRI of 105 people with obstructive sleep apnoea were examined to identify the presence of a tendinous connection between the mandible and the lateral airway. Length of the tendinous tract and airway dimensions were measured in the neutral and advanced positions using a temporary device. Participants were supplied with a custom- fitted Mandibular advancement splint (MAS) and treatment response was assessed after acclimatization. Results : 63% of participants had a tendinous lateral connection. The amount of possible mandibular advancement was greater in the non- tendon group (4.6 ± 1.4 mm absent vs. 4.0 ± 1.2 mm present, p = 0.04) with midline antero- posterior airway dimension also greater (1.6 ± 1.7 mm non- tendon vs. 0.6 ± 2.3 mm, p = 0.04). The non- tendon group were more likely to have a complete response to MAS (treatment AHI < 10 events/hr, 44% vs. 32%) but were less likely to complete acclimatization (69% vs. 88%, χ2 (3) = 10.578, p = 0.014). Conclusion : A tendinous lateral tract was associated with smaller achievable amount of mandibular advancement. People without detectable tendon were more likely to have a complete response to MAS treatment, but were less likely to tolerate MAS for reasons that are incompletely understood.