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Distinct patterns of respiratory difficulty in young children with achondroplasia: a clinical, sleep, and lung
R C Tasker1, I Dundas, A Laverty
1Paediatric Intensive Care Unit, Great Ormond Street Hospital for Children, London, UK.
Insights
Infants with achondroplasia experience respiratory issues due to distinct anatomical causes, leading to varied outcomes from sleep apnea to cardiorespiratory failure.
Area of Science:
- Pediatric Pulmonology
- Genetics
- Sleep Medicine
Background:
- Achondroplasia frequently causes respiratory difficulties in infants.
- Cardiorespiratory and sleep dysfunction are significant concerns in affected infants.
Purpose of the Study:
- To document lung growth patterns in infants with achondroplasia.
- To identify the causes of cardiorespiratory and sleep dysfunction in these infants.
Main Methods:
- Seventeen infants with achondroplasia and early-onset respiratory symptoms were prospectively studied.
- Clinical evaluations, sleep studies, and lung function tests were performed.
Main Results:
- Three distinct groups emerged based on symptom severity and underlying causes.
- Group 1: mild symptoms, obstructive sleep apnea. Group 2: obstructive sleep apnea, hydrocephalus, small foramen magnum. Group 3: severe symptoms, cor pulmonale, cardiorespiratory failure, obstructive sleep apnea, reflux, and stenosis of cranial foramina.
- Lung function initially showed no restriction, but worsened with growth, indicating increased airway resistance and reduced compliance.
Conclusions:
- Distinct phenotypes of achondroplasia-related respiratory dysfunction were identified, linked to specific anatomical abnormalities.
- Group 1: midfacial hypoplasia. Group 2: jugular foramen stenosis. Group 3: hypoglossal canal stenosis.
- These findings suggest localized alterations in chondrocranial development contribute to the varied clinical presentations.
Aim:
Achondroplasia can result in respiratory difficulty in early infancy. The aim of this study was to document lung growth during infancy, together with the cause of any cardiorespiratory and sleep dysfunction.
Patients And Methods:
Seventeen prospectively ascertained infants (14 boys and three girls) with respiratory symptoms starting before 1 year of age underwent clinical, sleep, and lung function studies.
Results:
Three distinct groups were identified. Group 1 (n = 6) were the least symptomatic and only had obstructive sleep apnoea. Group 2 (n = 6) had obstructive sleep apnoea of muscular aetiology and, neurologically, hydrocephalus and a small foramen magnum were common. Group 3 (n = 5), the most severely affected group, all developed cor pulmonale, with three deaths occurring as a result of terminal cardiorespiratory failure. All five had obstructive sleep apnoea with a muscular aetiology (a small foramen magnum predominated) with severe or moderately severe gastro-oesophageal reflux. Initially, lung function studies found no evidence of restriction or reduced lung volumes standardised according to weight. However, with growth these infants had worsening function, with raised airway resistance and severe reductions in respiratory compliance.
Conclusions:
These groups appear to be distinct phenotypes with distinct anatomical aetiologies: "relative" adenotonsillar hypertrophy, resulting from a degree of midfacial hypoplasia (group 1); muscular upper airway obstruction along with progressive hydrocephalus, resulting from jugular foramen stenosis (group 2); and muscular upper airway obstruction, but without hydrocephalus, resulting from hypoglossal canal stenosis with or without foramen magnum compression and no jugular foramen stenosis (group 3). The aetiology of these abnormalities is consistent with localised alteration of chondrocranial development: rostral, intermediary and caudal in groups 1, 2, and 3, respectively.