Utility of Cephalometry and Acoustic Pharyngometry for the Assessment of Moderate to Severe Obstructive Sleep Apnea Before Treatment in Childhood

Purpose: The ERS Statement dealing with childhood obstructive sleep apnea (OSA) declared that cephalometry and acoustic pharyngometry may be useful exams for the management of OSA. The objective of our cross-sectional study was to evaluate the correlations between the severity of OSA, namely obstructive apnea-hypopnea index (OAHI), and indices obtained from both acoustic pharyngometry and cephalometry in children referred for OSA treatment. Methods: Children referred for treatment of their moderate to severe OSA (AHI ≥ 5/hour) underwent acoustic pharyngometry in sitting and supine positions (measurement of pharyngeal volume and calculation of estimated pharyngeal compliance) and cephalometry (measurement of Frankfort Mandibular plane Angle: FMA and Frankfort Mandibular Incisal Angle: FMIA, hyoid bone distance to mandibular plane). Results: Two hundred and five consecutive children were enrolled (mean age ± SD: 11.2 ± 3.7 years, 73 females, type 1 OSA "enlarged tonsils”: 55 children, type 2 "obese”: 80, type 3 "syndromes”: 70). In a multiple regression analysis, only FMA and hyoid bone distance remained independently linked to OAHI (adjusted r 2 of the model: 0.12, p< 0.001, weak explanatory power). The FMA angle allowed differentiating normodivergence (21°< FMA < 29°: 41% of the children), hyperdivergence (FMA ≥ 29°: 32%), and hypodivergence (≤ 21: 27%). The participants with hyperdivergence were younger, less obese, and had a longer lower face (adenoid facies). In a multiple regression analysis, only height and FMIA remained independently linked to pharyngeal volume (adjusted r 2 of the model: 0.32, p< 0.001, moderate explanatory power). Conclusion: Childhood OSA can be associated with hypodivergence. Its severity is linked to craniofacial morphology, and cephalometry provides additional endotypic information in selected children.