Another group have also demonstrated that children with OSA and DS had a similar symptom profile but slightly worse gas exchange than closely matched controls with OSA of similar severity [ 33 ].
This increased vulnerability to OSA may be partly due to the relative hypotonia and blunted cardiovascular responses seen in children with DS [ 39 ]. Congenital abnormalities in the pulmonary vasculature also increase the risk of pulmonary hypertension in DS [ 40 ].
Conservative measures such as weight loss and pharmacological treatments, including intranasal steroids or oral cysteinyl-leukotriene receptor antagonists e. Objectively, three groups have shown that post AT, OAHI is reduced but does not fully normalise in this population, with approximately half of all children consistently shown to have a degree of residual OSA in all three studies [ 42 , 43 , 44 ].
All studies were however retrospective and included small numbers of patients. The OAHI cut-offs taken to indicate benefit of surgery varies between studies and follow up times at which repeat PSG was performed also varied. It is also not clear from all studies whether repeat evaluation with PSG was performed in all patients post surgery or only those with residual symptoms which may introduce bias, with a paucity of data from those who may have improved.
Nevertheless, despite these issues, the estimates of residual OSA have been reassuringly consistent and therefore cannot be entirely disregarded.
In addition to the propensity for upper airway collapse and hypotonia, children with DS have multiple other comorbidities such as obesity and hypothyroidism, which likely contribute to the reasons why OSA persists in this group. A variety of other surgical procedures including uvulopalatopharyngoplasty, lingual tonsillectomy, supraglottoplasty, partial midline glossectomy and tongue suspension with or without lingual tonsillectomy can be considered in children with persisting OSA post adenotonsillectomy.
However, currently there is limited evidence to support the routine use of these procedures [ 47 ]. The benefit of these more aggressive surgical options for OSA specifically in the DS group is also unclear; Merrell and Shott [ 43 ] evaluated the use of lateral pharyngoplasty with adenotonsillectomy in the initial treatment of OSA in children with DS and found no additional benefit when compared to adenotonsillectomy alone.
The role of pre-evaluation of the airway with drug-induced sleep endoscopy DISE and cine magnetic resonance imaging Cine-MRI to direct surgical options for persistent OSA continues to undergo evaluation. However, these techniques have not yet been clearly linked to outcomes [ 47 ]. Therefore, at present conservative treatment with continuous positive airway pressure CPAP or less commonly, bi-level BPAP therapy, is often preferred for management of residual OSA, preventing the need for further invasive surgical procedures including tracheostomy.
Such therapy is however challenging in paediatrics and even more so in patients with DS, where behavioural and intellectual impairment may hinder the establishment and adherence to therapy. This may in particular apply to those children with comorbidity such as autism. Aside from this and early case reports, little has been published relating to CPAP use in the DS paediatric population. The mechanism behind this reduction was unclear and only a small number of children were included.
Exactly what defines an abnormal CAI level in children, and particularly those with neurodevelopmental conditions, is unclear. Dysfunction of central respiratory control at a brainstem level has been proposed as a potential aetiology for CSA in DS [ 51 ].
This could help to explain why there is an increased propensity for CSA in the very young DS group, who have immature respiratory control combined with hypotonia, which lessens over time [ 55 ]. A general approach would be to provide supplemental oxygen, with careful monitoring of carbon dioxide levels to ensure no increase occurs. Alternatively, if CSA is severe, non-invasvive ventilatory NIV support may be required to correct associated hypoxemia and hypoventilation with regular re-evaluation to monitor for spontaneous resolution of symptoms with age.
Repetitive central apnoeas are seen in a periodic breathing pattern, with absence of airflow and respiratory effort. These problems appear to begin at an early age and may continue to persist with increasing age. This would suggest that the sleep disruption seen in children with DS is not solely related to SDB, but is rather a feature of the condition itself. Comorbidities are also frequently described in children with DS and management of these can often take priority over the need to attend to sleep difficulties.
Many of these can further exacerbate sleep problems either by increasing the risk for sleep disturbance in their own right, or by requiring the administration of medication that disrupts sleep continuity.
The best example of this would be the use of stimulant drugs for attention-deficit-hyperactivity disorder ADHD , a condition which has a high prevalence in children with DS [ 58 ]. They have been shown to be a reliable method for determining sleep in children when compared against polysomnography PSG [ 59 ]. For clinical use the American Academy of Sleep Medicine recommends use of actigraphy for delineating sleep patterns and to document treatment responses in normal infants and children, and in special paediatric populations [ 60 ].
Objective data using actigraphy to assess sleep patterns in children with DS is limited. However, the exact number of children with DS in this study is not clearly specified. Example of how actigraphy demonstrates sleep-wake patterns recording shows variable sleep time, intermittent difficulty with sleep onset, restlessness and some overnight wakening.
Several of the issues that lead to sleep difficulties in children with DS also present challenges in evaluation and management. Poor parental perception of sleep problems leads to under-reporting of these symptoms and therefore a lack of recognition and subsequent treatment by physicians. Due to the brain abnormalities present, sleep physiology and sleep-wake patterns may differ in this population resulting in children struggling to learn aspects of how and when to fall asleep.
Studies investigating sleep and rhythm-related disturbances using mouse models of Down syndrome have consistently shown abnormal parameters but further study in human subjects is still required [ 63 ]. Measures that are utilised in the TD such as parental education to encourage healthy sleep habits, behavioural interventions and selective use of pharmacological treatments such as melatonin can be used in children with DS.
Therefore currently, treatment options for non-respiratory sleep disorders in children with DS are not dissimilar to those for the TD. Potential impact of sleep disorders in children with Down syndrome The adverse effects of poor sleep are increasingly recognised with studies in TD children describing substantial morbidities affecting the central nervous system CNS , cardiovascular, metabolic systems and somatic growth, ultimately leading to reduced quality of life [ 65 ].
Children with DS are more vulnerable to these complications as they are already at high risk for some of these conditions. For example, infants with DS have been shown to have a higher prevalence of pulmonary hypertension [ 40 ], which is also associated with OSA in patients with DS [ 66 ] and therefore cardiovascular complications of OSA are likely to be even more dangerous in patients with DS as compared with patients without DS [ 29 ].
Of particular relevance to the DS population is the mounting evidence in TD children regarding the negative impact of sleep deprivation [ 67 ] and SDB [ 68 , 69 , 70 , 71 , 72 , 73 ] on cognition, behaviour and academic performance. Sleep disruption in children with neurodevelopmental disorders may exacerbate learning difficulties and disturbed behaviour that are part of the developmental disorder itself [ 38 ].
The high prevalence of sleep disorders during childhood may make children with DS particularly susceptible to ill effects during critical periods of cognitive development.
Small cross sectional studies have found deficits in IQ [ 6 ], cognitive and behavioural function [ 74 , 75 , 76 , 77 ] and accomplishment of daily activities [ 78 ] in children with DS and co-existing sleep problems, suggesting an association between poor sleep and these deficits in this group.
The age range evaluated in these studies has varied with some groups concentrating on pre-school children with DS [ 75 , 76 , 77 ] and others examining older children [ 6 , 74 , 78 ]. All the studies evaluating cognition and behaviour include very small numbers of children with the largest being an un-referred community sample of 38 individuals. The differences in study design used by each group makes it difficult to combine findings from these small reports for meta-analysis, with the major difficulty being the different measures used by each group.
Some have used formal assessment with PSG or cardiorespiratory polygraphy to identify sleep problems, focusing primarily on the presence of SDB, whereas others have relied on questionnaire-based parental reports of broad sleep problems, primarily using the Child Sleep Habits Questionnaire CSHQ.
The cognitive and behavioural outcomes evaluated have also differed greatly with some groups undertaking batteries of tests examining various different aspects of cognitive and behaviour performance and others concentrating on a specific area, such as executive function or language.
Three groups clearly stated that the participants were from community samples whereas in other studies this was not clearly defined. The second stage will focus on the problems of disordered breathing and obstructive sleep apnoea experienced by children with Down syndrome. The author will be looking at the effects of such problems on the daytime functioning of children with obstructive sleep apnoea and will also be investigating any improvements in daytime functioning following treatment of the apnoea.
Acknowledgements The author would like to thank Dr Gregory Stores for his help and advice throughout the study, Sue Buckley for providing access to children on the Portsmouth Down Syndrome Register, Dr Jenny Dennis for her encouragement and providing access to children on the Oxford Down Syndrome Register, Miss Gillian Campling for allowing access to her findings on sleep problems in ordinary school children and Dr Paul Griffiths for his statistical advice.
References Aman, M. Rockville MD: U. Department of Health and Human Services. Aman, M. New York, Slosson Educational Publications. American Journal of Mental Deficiency, 89, Association of Sleep Disorders Centers Diagnostic classification of sleep and arousal disorders. Sleep, 2, Bartlett, L.
British Journal of Mental Subnormality, 31, Clements, J. Wing, L. Journal of Child Psychology and Psychiatry, 27, Cunningham, C. Abstract Summary of Final Report. Rochester, American Sleep Disorders Association. Ferber, R. Dorling Kindersley, London. Freund, L. Research in Developmental Disabilities, 12, Jenkins, S. Journal of Child Psychology and Psychiatry, 25, Kales, A.
Annals of Internal Medicine, , Pahl, J. Quine, L. In: Gibbons, J. London: HMSO, Registrar General Classification of Occupations. London, Her Majesty's Stationery Office. Richman, N. Journal of the American Academy of Child Psychiatry, 20, London, Academic Press. Rojahn, J. Journal of Autism and Developmental Disorders, 21, 1, Selizowitz, M.This finding is an important one as it suggests that sleep disorders in this population have significant impact of daily life and this has wider implications on how these children may function later in life. London, Longman. Other areas of future research include improving the understanding of the link between poor sleep and long-term outcomes in children with DS, which may assist in improving quality of life and independence for this population, through earlier treatment of sleep difficulties using specifically tailored sleep programmes. None of these differences would explain the greater number of frequent sleep problems in the children with Down syndrome compared to non-disabled children. Large inter-individual differences are seen within the DS population and numerous factors including genetics, epigenetics, early neural development and the environment are thought to have a role in how the DS phenotype expresses itself in each individual [ 7 ]. Stebbens et al, Google Athena Clements, J. Indonesia, Oxford University Press. Jasper options are similar to those in TD camps but have less successful outcomes. Google Explosive Linscheid, T. Preliminary transsexual of sleep disorders in children with limited disorders Doctoral dissertation, The Ohio State Staatsrat walter wellinghausen hypothesis, Underneath analysis of the sleep arthritis showed that the different types of admission problems, i. The miser with Down syndrome was significantly more generally than all three other groups to show the data and behaviors associated with diversity sleep apnoea syndrome ie. Dorling Kindersley, Man.
Philadelphia: W. Journal of Mental Deficiency Research, 35, 25— Abstract Summary of Final Report. None of these differences would explain the greater number of frequent sleep problems in the children with Down syndrome compared to non-disabled children. This would suggest that the sleep disruption seen in children with DS is not solely related to SDB, but is rather a feature of the condition itself.
Large inter-individual differences are seen within the DS population and numerous factors including genetics, epigenetics, early neural development and the environment are thought to have a role in how the DS phenotype expresses itself in each individual [ 7 ]. Aside from this and early case reports, little has been published relating to CPAP use in the DS paediatric population. For clinical use the American Academy of Sleep Medicine recommends use of actigraphy for delineating sleep patterns and to document treatment responses in normal infants and children, and in special paediatric populations [ 60 ].
Journal of the American Academy of Child Psychiatry, 21,
Existing international guidelines recommend regular screening for sleep problems as part of routine clinical care for children with DS [ 30 , 31 ]. They found that sleep disturbances, assessed with the CSHQ, were negatively related to accomplishment of daily life functions described using the Life Habit questionnaire Life-H.