Laryngomalacia (LM) Flashcards
Define Laryngomalacia (LM).
Congenital abnormality of the larynx cartilage that predisposes to dynamic supraglottic collapse during the inspiratory phase of respiration, resulting in intermittent upper airway obstruction and stridor.
What are differential diagnoses for LM?
- Vocal cord palsy (present from birth)
- Subglottic stenosis (stridor biphasic rather than inspiratory)
- Laryngeal web/cleft/cyst
- Subglottic haemiangioma
Explain the aetiology for LM.
LM occurs due to a predisposition to dynamic supraglottic collapse that occurs during the inspiratory phase of respiration. The underlying factors have not yet been fully determined and there are several possible mechanisms, which may co-exist in some patients.
- Anatomical abnormalities, including short aryepiglottic folds and a curled ‘omega-shaped’ epiglottis, may contribute to the dynamic supraglottic narrowing.
- Neural pathways may be immature with resulting neuromuscular incoordination or hypotonia of the supralaryngeal airway.
- GORD has also been implicated and occurs in up to 80% of cases of LM. Further work is required before the aetiology is fully understood. It has been proposed that the mucosal inflammation and oedema that results from GORD may narrow the supraglottic airway, with the increased obstruction thus contributing to the LM.
What are risk factors for LM?
- GORD (50 – 80%)
- Neurological abnormalities (<20%)
- Male (M 2:1 F)
- Laryngeal anatomy abnormal
- Genetic syndromic disorders (Down’s)
Summarise the epidemiology of LM.
LM is the most common source of stridor in infants and the commonest congenital laryngeal anomaly. LM occurs in twice as many males as females and presents in the first few weeks of life with resolution within 12 to 24 months. Between 17% and 47% of patients with severe LM have been reported to have additional associated conditions or syndromes.
How does LM present?
Disease severity does not correlate with the intensity or frequency of stridor, but with the presence of associated symptoms. Several formal classification systems have been proposed, although none is in widespread use.
Onset often within 2 weeks of life. The noise becomes apparent within 2 weeks of birth and may increase in intensity/frequency until 6 to 8 months of age. It gradually resolves of its own accord, usually before 2 years of age.
What are common signs and symptoms of LM?
Stridor
Airway obstructive features
Recessions, tracheal tug, etc. (not usually present from birth which helps to differentiate from vocal cord palsy etc.)
Normal cry
What are uncommon signs and symptoms of LM?
Weight loss or FTT
Hypothonia
Dysmorphia
What is the clinical classification of mild LM?
With audible stridor and endoscopic features of LM, but no respiratory distress and no evidence of failure to thrive (i.e., a steady growth on weight centile charts).
What is the clinical classification of moderate LM?
With stridor, increased work of breathing, progressive feeding difficulties, and either weight loss or inadequate gain.
What is the clinical classification of severe LM?
With significant shortness of breath and airway obstruction, failure to thrive, dysphagia, apnoeas, hypoxia or hypercapnia, pulmonary hypertension, cor pulmonale, obstructive sleep apnoea, severe chest deformity (pectus excavatum), and delayed neuropsychomotor development.
What are appropriate investigations for LM?
Flexible laryngoscopy: Should be performed in all patients to assess laryngeal anatomy and related comorbidity (e.g., mucosal inflammation as evidence of GORD).
Topical anaesthesia is applied to the nasal mucosa so the upper airway and larynx may be examined while the child is fully awake. This allows assessment of vocal cord movement. However, flexible laryngoscopy does not provide for a reliable assessment of the subglottis or more distal airway.
Rigid laryngoscopy: Rigid laryngobronchoscopy can both confirm the findings of flexible laryngoscopy and reliably exclude co-existing airway lesions (e.g., tracheomalacia, subglottic stenosis, or vocal cord palsy). The incidence of second lesions has been reported to be between 12% and 64%.
What is the management for LM?
Most cases: Conservative approach
Severe stridor: Endoscopic surgery; Some cases may require tracheostomy.
What are complications associated with LM?
GORD, life-threatening airways obstruction, FTT, aspiration, pulmonary hypertension from hypoxaemia
What is the prognosis for LM?
Usually excellent with benign course and resolve at 12 - 24 months.
