O048 Ultrasound evaluation of the pterygomandibular raphe in Obstructive Sleep Apnoea

Abstract Introduction The pterygomandibular raphe (PMR) is an aponeurotic junction in the lateral upper airway soft tissue that may be an anatomical marker to predict mandibular advancement splint (MAS) treatment success (Brown et al. 2021). We evaluated the feasibility of a novel ultrasound (US) protocol to assess these lateral soft tissues, particularly PMR. Methods 31 participants (n=19(61.3%) female) with and without obstructive sleep apnoea (OSA) underwent lateral upper airway ultrasound. Inclusion criteria were age 18-75 years and previous polysomnogram. Eight participants also underwent MRI. The anatomical landmarks of PMR were measured. Results Participants were middle aged (56.5±15.9 years), overweight or obese (BMI 29.4±6.4 kg/m2) and had moderate OSA (mean AHI 24.4±21.7 events/hour). PMR was detected in all subjects. Submandibular gland depth (4.8±1.2 mm), US-PMR depth (18.1±3.0 mm) and US-PMR width (2.4±0.4 mm) were measured (n=31), and tonsil depth was recorded (n=24, 19.5±3.8 mm). US-PMR width measurements of OSA (n=24, 2.5±0.3 mm) and non-OSA (n=7, 2.5±0.6 mm) subjects were not different (p>0.05). MRI-PMR width values were similar (OSA 3.1±0.9 vs. non-OSA 2.5±1.5 mm, p>0.05). The width of MRI-PMR (2.7±1.2 mm) compared to and US-PMR (2.8±0.5 mm) was not significantly different (p>0.05). Discussion This research highlights the potential of US as a useful tool to study lateral upper airway tissues, particularly the PMR. We plan to correlate these findings in a larger number of participants who have undergone both MRI and US to demonstrate the sensitivity, specificity and clinical utility of US.