Introduction

Laryngomalacia (LM) is the most common cause of congenital stridor (noisy breathing) in infants, with an incidence of 1 in 2000 to 1 in 3000.¹ It is characterised by the “floppy” portions of the voice box collapsing inwards during inhalation and partially blocking the airway, most notably by the tissue above the vocal cords. The narrowed airways cause the distinctive squeaky sound found in infants with this condition. Some cases have exhibited feeding difficulties, apnea or hypoventilation.² 

Understanding the underlying pathology is essential for treating severe cases and for building parental trust by explaining that their child's condition usually resolves on its own and has a definable cause. In this article, we will explore this condition in detail, covering its causes, symptoms, and available treatment options.

Understanding normal airways

The larynx, located at the top of the body’s windpipe, is crucial in swallowing, breathing and voice production; its structure is supported by cartilage that prevents the airway from collapsing. In healthy infants, the larynx cartilage is sturdy enough to hold its shape during the breathing cycle. The upper airway structures remain open and can stay stable as the cartilage supports them.³ Coordinated muscle activity also aids with this action.

What are the distinguishing features of the airway structures in LM?

Abnormally soft vocal cords may cause tissues above the vocal cords to become misshapen. The epiglottis, in particular, may become curled into an omega shape, and the aryepiglottic folds may be shortened or tightened. The lack of support in the airway reduces its openness, which increases the likelihood of inward tissue collapse during inspiration.⁴

Causes of the “floppy” airway in LM

There is no singular cause of the “floppy” airway, and the reasons are largely unknown. However, a combination of factors can lead to this effect, namely:⁵

• Immature cartilage
• Neuromuscular immaturity
• Anatomic factors
• Gastroesophageal reflux disease (GERD)
• Genetic associations

Immature cartilage

This is the most common and primary cause of the “floppy” airway; some infants have more flexible, softer cartilage than others. Immature cartilage in the larynx is not rigid or strong enough to resist the inward air pressure during inhalation; hence, it can bend and collapse into the airway. This is not indicative of a disease; however, the immaturity of cartilage is a regular part of a child’s development. The issues with the soft cartilage often resolve by 12 to 24 months of age. As the infant grows, the cartilage typically becomes firmer, and symptoms reduce in severity.¹ However, due to the varying degrees of cartilage weakness, some children may have more noticeable symptoms.

Neuromuscular immaturity

This phenomenon refers to the lack of coordination between the brain, nerves, and muscles responsible for maintaining the airway in optimal functionality. When these systems are inadequate and inefficient, the muscles surrounding the larynx may not provide the necessary responsiveness or tone required, allowing tissues to collapse more easily. Reasons for this could be due to general developmental delay or part of the natural maturation process; in some cases, LM is more persistent if underlying neurological disorders are present. Studies have shown that infants with LM have different sensory and motor innervation of the larynx, particularly involving the superior laryngeal nerve. This nerve plays a crucial role in laryngeal tone and reflexes; dysfunction can result in delayed or inadequate reflexes, decreased muscle tone in the upper airway, and poor coordination of breathing and airway stabilisation.¹

Anatomic factors

Several anatomic variations can increase the disposition of a baby developing LM. For instance, as the cross-sectional area of the airway decreases, the “floppy” airway is more likely to develop. Structural differences, such as short aryepiglottic folds that help support the epiglottis, can cause it to pull inward and narrow the airway. Furthermore, the epiglottis may be misshapen or curled, which increases the likelihood of it folding backwards during inhalation. Some infants may also have extra mucosal tissue around the larynx, which increases the chances of dynamic collapse.⁶

Gastroesophageal reflux disease (GERD)

The association between LM and GERD has been studied extensively, with up to 80% of children with stridor also having some degree of gastroesophageal reflux. As a result, the acid exposure may cause further weakening of laryngeal tissues as well as oedema and inflammation. GERD can worsen existing airway collapse but also aggravate poor airway tone by stimulating laryngeal sensory nerve dysfunction, resulting in persistent hoarseness, discomfort and coughing.⁷ Treating GERD may reduce the severity of LM. Possible therapeutics include proton pump inhibitors and H2 blockers, depending on whether the symptoms are chronic or occasional.

Genetic associations

In very few cases, LM is associated with congenital syndromes such as Down syndrome or neuromuscular disorders such as cerebral palsy. The comorbidities of decreased muscle tone, poor neuromuscular coordination and anatomical anomalies may also increase the likelihood of a more severe form of LM, which might not resolve spontaneously as usually seen.⁸

Treatment options

Most cases of LM are mild, but symptoms may worsen with feeding or agitation. Babies may also exhibit cyanosis (a bluish discolouration of the hands and feet) and experience weight gain as a result. Symptoms are initially managed with parental reassurance and observation, though severe cases may require intervention. Parents should monitor feeding, breathing and weight of the baby, and stay aware of warning signs such as sleep apnea or distress. If symptoms worsen, supraglottoplasty may be used to correct LM-related obstruction by removing or reshaping excess larynx tissue.⁹

FAQs

What is LM in simple terms? 

LM is a condition in which the soft tissue above the voice box collapses during breathing, causing noisy, squeaky breathing (stridor) in infants.

Is LM dangerous? 

Usually not. Most cases are mild and improve as the baby grows; however, some cases are more severe and may require treatment.

What causes the airway to be “floppy”? 

This can be caused by numerous factors: immature cartilage, poor airway muscle or nerve coordination, anatomical abnormalities (e.g. curled epiglottis), and acid reflux irritating the airway.

When do symptoms usually appear? 

Symptoms typically appear within the first few weeks of life and are more noticeable when the baby is lying down, feeding, or crying.

Will the infant outgrow it? 

Yes, most babies outgrow LM by 12 to 24 months as their airway matures.

How is it diagnosed? 

With a flexible laryngoscopy, which is a thin camera inserted through the nose to view the larynx.

Can LM return after it goes away? 

No, once resolved, it typically does not recur; therefore, if symptoms reappear, other causes should be investigated.

Summary

LM is primarily caused by immature cartilage in the larynx, often worsened by neuromuscular incoordination, anatomic variations, and gastroesophageal reflux. In rare instances, it is part of a broader genetic or neurological syndrome. Understanding these factors helps guide clinical assessment and ensure that severe cases are promptly identified and treated. Fortunately, most infants improve with time and supportive care, with surgery reserved for only those with significant airway compromise or failure to thrive.