Differential impact of Crouzon and Apert syndromes on upper airways morphology: implications for Obstructive Sleep Apnoea

Children with syndromic craniosynostoses face high risk of obstructive sleep apnoea (OSA), but the underlying mechanisms remain unclear. This study investigated how Crouzon and Apert syndromes affect airway morphology and contribute to OSA, controlling for age and posture. We also examined the covariation between the upper airways and the craniofacial region (skeleton and soft tissues). We analysed 37 patients with syndromic craniosynostoses, and 53 control children aged from 0 to 49 months old. A set of 52 landmarks was placed on the 3D models of the upper airways and collected, when available, the apnoea-hypopnoea index (AHI). Our geometric morphometric analyses demonstrated that age, mouth openness and craniocervical posture significantly influenced airway shape, emphasizing the need for standardised imaging. After controlling these factors, we highlighted oropharynx changes in patients with Crouzon syndrome, while Apert syndrome altered the nasopharynx. No direct link between airway shape and OSA was found. Upper airways growth and its morphological covariation with the craniofacial region were not impacted by the diagnosis of syndromic craniosynostosis. Finally, these findings highlight syndrome-specific airway differences, FGFR mutations impacting both bone and surrounding soft tissues. This study provides valuable insights for more precise respiratory diagnoses and personalised treatment plans.