Introduction

Laryngomalacia is the most common cause of stridor in infants. The importance of early diagnosis cannot be overstated, as laryngomalacia can impact various facets of growth and development. To detect respiratory compromise, stridor and noisy breathing are essential symptoms to recognise, as they may indicate the degree of airway obstruction. The upper airway must be thoroughly evaluated in children suspected of having laryngomalacia to ensure an accurate diagnosis and effective treatment. 

Laryngomalacia is characterised by varying degrees of severity. A mild laryngomalacia can be treated with watchful waiting. Severe laryngomalacia, on the other hand, increases the body's work of breathing to the point where more calories are spent on breathing, resulting in poor growth in the infant.¹

Etiology 

Laryngomalacia has been linked to many causal theories, but the bottom line is that the soft, immature cartilages of the infant larynx collapse upon inspiration, causing noisy breathing (inspiratory stridor). A leading theory suggests that the laryngeal nerves are abnormally integrated, which causes altered laryngeal tone.² The proposed theory confirms pathological research indicating an enlarged supraglottic nerve diameter in patients with severe laryngomalacia.³ 

Other theories, such as the imbalance between supply and demand upon infant inhalation, require further studies.⁴ Furthermore, there has not been any evidence that gastroesophageal reflux causes laryngomalacia; however, nearly 60% of infants have concomitant acid reflux disease.⁵ As a result of reflux, the upper airway may be irritated and edematous, potentially worsening obstruction. Laryngomalacia occurs more frequently in infants with concurrent neuromuscular disease, characterised by global hypotonia that manifests in the airway muscles.⁶

Presentation 

Laryngomalacia is characterised by inspiratory stridor that generally exacerbates with feeding, crying, supine lying, and agitation. Within the first few weeks of life, the symptoms begin, peak at 6 to 8 months, and resolve by 12 to 24 months.⁷  Usually, the disease is diagnosed within the first 4 months of life.² 

In addition to inspiratory stridor, a classic symptom of laryngomalacia, regurgitation, vomiting, coughing, choking, and slow feeding are some of the most common associated symptoms. Due to laryngomalacia, infants may have difficulty coordinating the suck, swallow, breath sequence necessary for feeding.⁸ As a result of the increased metabolic demand associated with coordinating eating and breathing against the partially obstructed airway, weight loss and malnutrition may occur if the infant is not treated. Other symptoms, which are less common but still concerning, include tachypnea (rapid, shallow breathing), suprasternal and substernal retractions, cyanosis (blue hands and feet), and pectus excavatum. 

Moreover, a lack of recognition and proper management of chronic hypoxia, caused by airway obstruction, can lead to pulmonary hypertension.⁹ Therefore, there is a need to differentiate laryngomalacia from other causes of noisy breathing, as misdiagnoses include tracheomalacia, asthma, bronchiolitis, and reactive airway disease. Identifying specific breathing patterns and phases of the respiratory cycle is essential to accurate assessment and diagnosis. 

There are three types of noisy breathing: wheezing, stertor, and stridor. The cause of wheezing, typically expiratory, is pathology of the lower respiratory tract. In most cases, adenotonsillar hypertrophy is associated with stertor, a low-pitched inspiratory sound. The term stridor refers to high-pitched sounds that are usually caused by obstruction of the supraglottic or glottic membrane, obstruction of the trachea (e.g., tracheomalacia), or obstructions of both (e.g., viral croup). If stridor persists, an otolaryngologist should be consulted.⁹ 

Disease spectrum 

Mild laryngomalacia

In terms of severity, laryngomalacia can be categorized as mild, moderate, and severe. Stridor is not classified according to quantity, but rather according to the accompanying eating and obstructive symptoms. A mild illness is usually accompanied by inconsistent inspiratory stridors. Moderate disease is usually characterised by stridor and eating-related symptoms, and it usually improves with acid suppression treatments. In severe cases, surgery, usually supraglottoplasty, is required. 

A better understanding of symptoms and the unique factors affecting disease severity will enable otolaryngologists to determine which patients require further treatment.⁹ At the time of presentation to a health care provider, approximately 40% of infants will have mild laryngomalacia. There is inspiratory stridor as well as coughing, choking, and regurgitation associated with feeding. The suck swallow breath sequence is coordinated, and they feed comfortably. There is no link between airway obstruction and hypoxia. In general, they have an oxygen saturation of between 98 and 100 per cent at rest.¹⁰ Approximately 70% of patients who present with mild disease will have an uneventful course and resolve without requiring further treatment. The remaining 30% who present with worsening reflux symptoms that interfere with eating will be categorised as moderate disease. In addition to reflux-related symptoms, mild disease and SAO2s remaining at 96% are indicators of moderate disease progression.^10,2  

Moderate laryngomalacia

It is estimated that up to 40% of patients will have moderate laryngomalacia at the time of presentation. Their caregivers describe them as fussy and hard to feed, even though they present with the typical stridor. They often display feeding-related symptoms such as coughing, choking, regurgitation, and cyanosis. These feeding problems can lead to aspiration, weight loss, and laborious feeding if they are not recognised and managed. 

Several strategies exist to improve feeding symptoms, including pacing, thickening formula/breastmilk, and feeding upright. Here is a description of the mechanism behind acid suppression treatment. It has been reported that 72% of infants with this management strategy will have resolved their symptoms within 12 months. Moderate laryngomalacia does not cause hypoxia in infants, but they have a lower average resting SAO2 of 96%.^10,2 It is important to closely monitor infants since up to 28% develop severe disease and worsening symptoms despite feeding modifications and acid suppression therapy. A surgical intervention is required in these patients.⁸ A moderately ill infant with an average resting SAO2 of 91% is also more likely to require surgery, usually supraglottoplasty.^10,2   

Severe laryngomalacia

At the time of presentation to a health care provider, 20%of infants have severe laryngomalacia. They present with inspiratory stridor and other associated symptoms such as recurrent cyanosis (blue hands and feet), sleep apnea, difficulty eating, and aspiration. It is possible to develop pectus excavatum by retracting the suprasternal and subcostal muscles. 

Those with severe disease have an average resting SAO2 of 86%.^10,2 Chronic hypoxia can cause pulmonary hypertension and cor pulmonale if not recognised and managed. Surgery will likely be necessary for those with severe disease, as well as acid suppression treatment. Through an endoscope, the obstructing, collapsing tissue is removed through supraglottoplasty, the mainstay of surgical intervention. Tracheotomies are reserved for supraglottoplasty failures and those with multiple medical conditions.^10,2

Medical comorbidities

In severe cases of laryngomalacia, surgical intervention is reserved for patients exhibiting respiratory distress, stridor, and feeding difficulties. There are several absolute indications, including significant obstruction with marked retractions, pectus excavatum, cor pulmonale, pulmonary hypertension, and hypoxia. Among the relative indications are recurrent aspiration pneumonia, weight loss without overt failure to thrive, and feeding difficulties that do not respond to medical treatment. 

The surgical decision is made based on the infant's clinical trajectory. In supraglottoplasty, redundant arytenoid mucosa under anaesthesia is resected via endoscopic assessment. Approximately 94% of patients with anatomic obstructions have symptom resolution with a low complication rate following this procedure. Nevertheless, 19–45% of patients may require revision surgery or tracheostomy, particularly if comorbidities are present. A tracheostomy is reserved for airway obstructions that are refractory and life-threatening.^7,2

Summary 

An infant's inspiratory stridor is usually caused by laryngomalacia, or collapse of the supraglottic airway due to immature cartilage or neuromuscular dysfunction. Symptoms usually appear in the first few weeks of life, peak between six and eight months, and disappear by 24 months. Symptoms of stridor include worsening stridor while feeding, crying, or lying supine, as well as eating difficulties, regurgitation, and, in severe cases, cyanosis. Based on associated symptoms and oxygen saturation levels, diseases are classified as mild, moderate, or severe. 

The majority of mild cases resolve spontaneously, while moderate cases may require acid suppression and modification of the feeding regimen. There is often a need for surgical intervention in severe cases. These cases are typically associated with hypoxia (SpO2 86%) and an increased risk of pulmonary hypertension. A supraglottoplasty is the most common surgical procedure with a high success rate (~94%). If the condition persists or is life-threatening, revision surgery or a tracheostomy may be needed. To prevent complications and ensure a healthy development, it is essential to diagnose the problem accurately and begin treatment as early as possible.

FAQs

What causes laryngomalacia, and how is it diagnosed?

A supraglottic airway collapse causes it, which can be diagnosed by clinical features and laryngoscopic examination.

How is laryngomalacia classified and managed?

Mild, moderate, and severe cases are classified and managed appropriately.

When is surgery indicated, and what are the outcomes?

The surgery is performed in severe cases and is successful in most infants with few complications.