Laryngomalacia also called “discoordinate pharyngo-laryngomalacia” is the most common congenital lesion of the larynx (60-70%) and is the most common cause of congenital stridor in neonates and infants.
The condition is characterized by partial or complete obstruction of supraglottic laryngeal structures on inspiration because of excess mucosa, abnormal and/or reduced laryngeal tone.
The term laryngomalacia was coined by Jackson and Jackson in 1942.
Epidemiology & Etiology
The exact etiology of laryngomalacia is unknown. Three theories are proposed to explain the pathogenesis.
- Anatomic theory: The cause of laryngomalacia is abnormal shape and structure of larynx. Manning et al found that a mean ratio of aryepiglottic fold/glottic length of patients with severe laryngomalacia was significantly lower than controls without laryngomalacia.
- Cartilaginous theory: the delay in maturation of supporting laryngeal cartilages, causes an inward collapse of supraglottic structures on inspiration.
- Neurologic theory: This is the most recent one and most accepted one. Neurosensory dysfunction leads to a lack of neuromuscular support to pharyngolarynx resulting in weak laryngeal tone is considered to be the etiology. This theory of altered nerve function was supported by the studies of Munson et al, who observed that nerve perimeter and surface area of superior laryngeal nerve branches within supra-arytenoid tissue of children with laryngomalacia are greater compared with age-matched autopsy tissues.
The typical clinical presentation is noisy breathing (stridor) at or shortly after birth (2-4 weeks), most commonly in premature babies.
The stridor is a high pitched, fluttering inspiratory one, which worsens when the infant is in a supine position, during feeding, is active or upset and disappears on sleeping.
The severity of stridor increases as the child becomes active for the first 9 months and then gradually diminishes, disappearing at the age of 2. On average, stridor resolves by 8 months of age. Very rarely stridor may persist into late childhood.
Feeding difficulties will be another complaint, because of the disruption in a delicate balance between suck-swallow sequence and respiration.
Gastroesophageal reflux disease (GERD) is strongly associated with laryngomalacia because of the high negative intrathoracic pressure and also may be due to defective lower esophageal sphincter tone. Symptoms of GERD like aspiration, coughing, choking, regurgitation with feeds, slow oral intake etc may be present.
Other causes of stridor must be considered when evaluating a child with these symptoms.
These include vallecular cyst, epiglottitis, tracheomalacia, vascular anomalies, subglottic stenosis /cyst/hemangioma, vocal cord paralysis, laryngeal web, papillomatosis, etc.
One of the most useful ways to differentiate between causes of stridor is to identify in which phase of respiration the sound is heard. Different causes of airway obstruction causes stridor during different phases of respiration. In laryngomalacia, the stridor will be typically in the inspiratory phase of respiration.
Proper history should be obtained with a focus on antenatal, natal and postnatal events as well as current symptoms. Prenatal complications, gestational age at birth, birth weight, history of endotracheal intubation, ICU admissions etc should be noted.
Special attention should be given on the child’s weight gain, feeding problems, feeding time, reflux symptoms and any history of pneumonia
Complete physical and clinical examination should be done including general appearance, vitals, the weight of the child, presence of stridor, work of breathing – the presence of suprasternal retractions or abdominal muscle usage should be done. Auscultation of lung fields should be done and the character of stridor should be identified. Presence of any chest wall abnormalities like pectus excavatum should be noted.
A Flexible fiberoptic naso-pharyngo-laryngoscopy (NPL) can be done to confirm the diagnosis and is enough in most patients. NPL is found to have 88% reliability for the diagnosis of laryngomalacia. The anatomic abnormalities observed during NPL scopy in laryngomalacia are:
- Long, tightly curled, soft epiglottis which is omega (Ω) shaped.
- Tall, bulky and anteroposteriorly short aryepiglottic fold, tightly tethered to the epiglottis.
- Tall, narrow and deep supraglottic inter arytenoid cleft.
- Supraglottic collapse – the long epiglottis, redundant mucosa and submucosa of aryepiglottic folds prolapses medially into airway obscuring evaluation of subglottis.
Examination of larynx, trachea, and bronchi under Anesthesia (EUA laryngo-tracheo-bronchoscopy) under spontaneous breathing can be done when the child is having severe stridor, absence of any abnormality on NPL, failure to thrive, symptoms of aspiration or any atypical features. In 20% cases, other associated airway abnormality may present and in 5% cases, it may be clinically significant.
A digital X-ray / computed tomogram chest can be obtained, to rule out any associated airway anomalies.
Other tests like modified barium swallow or functional endoscopic evaluation of swallowing may be considered, particularly if the concern of aspiration exists.
An esophagoscopy is also recommended to exclude any associated reflux disease.
Classification of laryngomalacia
Many classification systems are proposed for laryngomalacia, but no single system has been universally accepted. Modified Holinger Classification is the most commonly accepted system for laryngomalacia.
|Type 1||The inward collapse of aryepiglottic folds on inspiration|
|Type II||Curled tubular epiglottis with short aryepiglottic folds, which collapse circumferentially on inspiration|
|Type III||An overhanging epiglottis, that collapses posteriorly, obstructing laryngeal inlet on inspiration.|
If surgical intervention is needed, the classification of anatomic site collapse can help in directing the surgical approach.
In 90% of cases, no intervention is needed, but the parents need to be reassured and advised to have periodic weight monitoring and follow up. Feeding modifications including pacing, thickening of feeds and upright positioning while feeding should be advised.
Though there is a lack of evidence for the role of anti-reflux medications in laryngomalacia, it is recommended to have acid suppression therapy especially in children with feeding difficulties and GERD symptoms. Proton pump inhibitors and H2 blocker therapy can be considered in such children.
In children with severe symptoms (10% cases) – with substantial sternal and intercostal retraction, pectus excavatum, failure to thrive, persistent stridor after 18-24 months, feeding anomalies, gastric reflux enhanced by increased negative intrathoracic pressure, obstructive sleep apnea, associated comorbidities (eg: cyanotic heart diseases, cor pulmonale, pulmonary hypertension) – restoration of airway by surgery is needed.
The most common surgical procedure done is aryepiglottoplasty / supraglottoplasty. In this procedure, depending on the severity of airway collapse, the aryepiglottic folds are released from edges of the epiglottis, redundant mucosa and submucosal tissues are excised with part or all of the cuneiform cartilages. Care should be taken to preserve the bridge of mucosa, between arytenoids to prevent interarytenoid scarring.
90% of children will get immediate relief from stridor following surgery. It is also found to reduce gastric reflux also.
Complications were observed in 4% of children. These include laryngeal edema, granulation tissue formation, supraglottic stenosis, etc.
Lower success rates are seen in premature infants, children with congenital syndromes and with neurologic anomalies. In those children with persistent stridor even after surgery, other underlying hypotonic neurological disorders should be suspected.
Noninvasive ventilation (NIV) may be indicated in some infants with comorbid conditions or failing to respond to surgical management.
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