Obstructive sleep apnoea in children. Diagnostic challenges and cognitive correlates, a focus on Down Syndrome

Obstructive sleep apnoea (OSA) affects up to 4% of otherwise healthy children. It is common in the pre-school and primary school years when the tonsils and adenoids enlarge, making the upper airway vulnerable to collapse during sleep as the pharyngeal dilator muscles relax. This intermittent airway collapse may go unnoticed by parents and clinical signs, when the child is awake, are unreliable predictors of OSA. Data is presented that confirms the unreliability of ENT evaluation of OSA in a large group of typically-developing children. For this reason, children need to be monitored during sleep using objective measures. There is debate about the best way to measure OSA. International standards recommend polysomnography in a sleep laboratory, but access is limited in the UK. Polygraphy studies that do not include neurophysiological measures of sleep are a common alternative. Children with Down syndrome are at risk of OSA due to their cranio-facial anatomy and hypotonia. Few studies have reported the prevalence of OSA in young children with Down syndrome. None have reported cognitive measures in pre-schoolers. Data in 188 children under 6 years, evaluated with polygraphy, indicate a high prevalence (14%) of moderate to severe OSA at this age. Furthermore, executive function behaviour impairments are apparent with mild OSA. Screening for OSA is warranted but UK practice is variable. Pulse oximetry offers a simple screening approach and oximetry predictor variables are proposed that are robust in a clinical validation sample. A screening questionnaire requires further evaluation. In the typically-developing child, severity of OSA correlates poorly with degree of cognitive impairment. It is possible that important mediators of cognitive impairment have been overlooked. Data is presented on hearing loss, which is commonly co-morbid with adenotonsillar hypertrophy, as a novel potential mediator of cognitive impairment in OSA. Finally, novel data is presented that shows failure of sleep-dependent learning in children with Down syndrome. Whether this relates to OSA requires further study. Children with Down syndrome are vulnerable to OSA and already suffer cognitive impairment. Implementation of screening guidelines is recommended. Future research should clarify the appropriate treatment of OSA in these children to avoid cognitive decline