Laryngomalacia

OVERVIEW: What every practitioner needs to know

Are you sure your patient has laryngomalacia? What are the typical findings for this disease?

Upper airway obstruction in the neonatal period is not uncommon but it is usually mild and self-limiting. Simple measures are usually sufficient in managing mild airway symptoms, but further evaluation and management become necessary when signs and symptoms persist.

Noisy breathing, usually either stridor or sturtor, is the primary presenting sign and symptom of upper airway obstruction in the neonatal period.

Feeding difficulty and subsequent poor weight gain is the second most common symptom of upper airway obstruction. There are two reasons for this: the first is that the calories expended on the labor respiration are excessive; the second is that the feeding coordination necessary for a proper suck-swallow-breathe cycle is disrupted, causing the infant to choose either feeding or breathing; they always choose breathing.

Noisy Breathing

Noisy breathing is caused by turbulent air flow. Air flow in the larger upper airways is generally laminar in nature. Obstructions or disturbances in laminar air flow causes turbulence, and turbulence is perceived in the history and physical examination as airway noise. Airway noise usually consists of sturtor, when turbulence occurs in the nasal cavity or nasopharynx, or stridor, when turbulence occurs in the hypopharynx, larynx, subglottis, or trachea.

The site and severity of airway obstruction can often be determined from physical examination. Careful auscultation of the airway – including chest, lower neck, upper neck, and adjacent to the nose and oral cavity – is necessary. Sturtor is more coarse upper airway sound demonstrated best near the nose and mouth. Since neonates are obligate nasal breathers, sturtor is usually present at rest and during feeding but absent or decreased during crying.

Stridor is best demonstrated over the upper chest and lower neck. Stridor may be inspiratory, expiratory, or biphasic. Stridor may be present during any or all activity levels – rest, feeding, or crying – and this may give clues to the cause and severity. Inspiratory stridor generally indicates an extrathoracic process such as laryngomalacia or subglottic stenosis. Expiratory stridor usually indicates an intrathoracic process such as tracheal compression, tracheomalacia, or complete tracheal rings. Biphasic stridor is present in more severe or progressive obstructions and indicates that prompt intervention is necessary.

Other signs and symptoms

Other signs and symptoms are frequent and are a result of the obstruction and increased work of breathing that is present. The severity of these signs and symptoms is an indication of the severity of the obstruction:

Retractions

Nasal flaring

Poor feeding

Inadequate weight gain or failure to thrive

Increased spitting up, gastroesophageal reflux (GER), or overt gastroesophageal reflux disease (GERD)

Cyanosis or cyanotic spells

Apparent life-threatening events

Desaturation events

Apnea bradycardia events

Laryngomalacia is the most common cause of stridor in the neonatal period. Stridor usually is not present at birth, but onset is usually within the first 1-2 weeks of life. Increased muscle mass, strength, and respiratory effort during the first weeks of life is thought to be the genesis of the early onset that is not present at birth. So consistent is this occurrence, stridor at birth is considered inconsistent with laryngomalacia and more likely to indicate vocal fold paralysis or subglottic stenosis. An increase in GER and subsequent upper airway edema may also be cause for delayed onset.

GER is almost always a contributing factor in laryngomalacia, but most agree it is secondary and not causative. Therefore treatment of GER is felt by most to play an important role in primary or secondary management.

What other disease/condition shares some of these symptoms?

Nasal or nasopharyngeal obstruction:

Idiopathic neonatal nasal congestion

Anterior nasal stenosis or piriform aperture stenosis

Unilateral or bilateral nasal choanal stenosis or atresia

Nasal or nasopharyngeal masses

Congenital dacrocystocele

Oropharyngeal obstruction:

Tongue base collapse secondary to decreased muscle tone

Micrognathia or retrognathia with relative macroglossia causing tongue base collapse

Macroglossia (primary)

Hypopharyngeal obstruction:

Vallecular cyst

Laryngomalacia

Glottic obstruction:

Unilateral or bilateral vocal fold paralysis

Laryngeal web or cleft

Postintubation edema and/or granulation

Laryngeal edema secondary to inflammation (GERD)

Subglottic obstruction:

Congenital or acquired subglottic stenosis

Subglottic cyst

Postintubation edema and/or granulation

Subglottic edema secondary to inflammation (GERD)

Tracheal obstruction:

Tracheomalacia

Complete tracheal rings

Extrinsic compression

Mediastinal masses

Vascular compression for innominate artery or other congenital cardiovascular anomalies

Vascular rings and slings

What caused this disease to develop at this time?

There are no known or universally accepted predisposing factors for the development of laryngomalacia. It is widely believed that GER or GERD plays a role in the development and/or progression of the disease.

There is increasing evidence that certain populations are at increased risk for having laryngomalacia, but the reason for this increased incidence is unknown. Very young children with obstructive sleep apnea, neurologically affected children, children with Trisomy 21, and children with other syndromes all appear to be at increased risk for larygomalacia.

Laryngomalacia was originally thought to be a result of immature cartilage formation in the supraglottic structures of the epiglottis, arytenoid, and cuneiform cartilages. Histologic studies failed to confirm this theory. Electromyographic, histologic, and neurologic studies have failed to support the theory that muscular or neuromuscular immaturity is the cause of laryngomalacia. Most recent evidence supports that congenital foreshortening of the aryepiglottic folds is the most consistent finding on examination.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Laboratory studies are generally unnecessary in mild laryngomalacia. In more severe cases, capillary blood gas measurement or serum bicarbonate measurement may be helpful in determining if acute or chronic hypoventilation is present. A complete blood count may be helpful to determine if undiagnosed anemia is present and contributory.

Diagnosis of Laryngomalacia and/or Other Upper Airway Obstruction

The diagnosis of laryngomalacia may be highly suspected by history and physical examination. The watchful waiting or empirical treatment of GER may be based on this diagnosis. Confirmation and the decision for treatment is best made by awake flexible fiberoptic nasolaryngoscopy. Alternative or secondary diagnoses may be made during this examination, making it a highly effective tool in the evaluation of the neonate’s upper airway. The procedure is safe, effective, and minimally invasive. Although used extensively by otolaryngologists, primary care providers and other specialists can learn and effectively perform this minor procedure with proper training.

Before performing this procedure, topical anesthesia and decongestion of the nasal mucosa is achieved with spray. A small flexible fiberoptic scope is passed through the nasal cavity and through the nasopharynx and is situated above the glottis. Visualization of the glottis is then performed during respiration and/or crying. Prolapse of the supraglottic structures during inspiration, associated with the characteristic inspiratory stridor, is diagnostic of laryngomalacia. The severity of the physical findings are classified as:

Mild – Prolapse of the arytenoid and cuneiform cartilages and/or overlying mucosa during inspiration

Moderate – Prolapse of the arytenoids and aryepiglottic folds during inspiration

Severe – Prolapse of the arytenoids, aryepiglottic folds, and epiglottis during inspiration

If the diagnosis of laryngomalacia is not confirmed during the nasolaryngoscopy, many of the previously mentioned diagnoses can be made or suspected.

Would imaging studies be helpful? If so, which ones?

Computed tomography (CT) of the nose and nasopharynx is the most helpful imaging modality for nasal obstruction. Axial images may demonstrate anterior or piriform aperture stenosis, choanal atresia, congenital dacrocystocele, or nasal obstruction due to congenital or neoplastic masses.

Congenital or neoplastic masses in the neonate may require magnetic resonance imaging (MRI) to further delineate the nature or extent of the mass.

Chest radiography should be obtained if intrathoracic causes of airway obstruction are suspected.

Barium swallow, echocardiographic evaluation of the heart and mediastinal vasculature, CT, and/or magnetic resonance imaging (MRI) of the chest may be necessary, depending on signs, symptoms, and findings of other diagnostic testing.

If you are able to confirm that the patient has laryngomalacia, what treatment should be initiated?

Most frequently, laryngomalacia requires no treatment. Close monitoring of stridor, and most importantly, feeding and weight gain are critical. A feeding diary, to document volumes and frequency, and weekly weight checks should be instituted.

Conservative measures to decrease GER should be instituted. These may include upright feeding posture, frequent burping to decrease air ingestion, upright positioning for 30-60 minutes after feeding, and thickening of formula/breast milk.

If significant GERD is thought to be contributory, an empirical trial of gastric acid suppression (H2 blocker or proton pump inhibitor) may be instituted.

Awake flexible fiberoptic laryngoscopy should be performed if the above measures are not effective. Consultation with an otolaryngologist should be carried out.

Once the diagnosis of laryngomalacia is confirmed by visualization of the supraglottic structures, any and all conservative measures not previously attempted should be instituted. At this point, some otolaryngologists may recommend complete operative microlaryngoscopy and rigid bronchoscopy. Some studies indicate a 15%-20% incidence of secondary upper airway abnormalities in children with moderate to severe laryngomalacia.

At this point barium swallow imaging and gastroenterology evaluation should be considered. Aspiration, either overt or silent, may be demonstrated by barium swallow. Gastroenterology evaluation may include pH probe, impedance probe, and upper endoscopy.

Supraglottoplasty: If secondary airway anomalies are not present and previous treatment options are exhausted, surgical treatment should be considered based on the severity of signs and symptoms. In most cases, supraglottoplasty is performed in conjunction with full endoscopic evaluation of the upper airway.

Supraglottoplasty consists of division of the aryepiglottic folds under direct endoscopic or microscopic visualization. In addition, varied amounts of mucosa may be trimmed from the aryepiglottic folds, over the arytenoid and/or cuneiform cartilages, or from the lateral edges of the epiglottis. Excessive mucosal division or excision may lead to aspiration, so care must be taken during the procedure. Repeated procedures may be necessary for further tissue incision/excision, but previously excised tissue cannot be replaced.

Secondary airway lesions may require surgical treatment. In a few cases with or without secondary lesions, tracheostomy may be required to manage severe upper airway obstruction. When obstruction is present from multiple causes at multiple levels, tracheostomy may often be the best course.

What are the adverse effects associated with each treatment option?

No treatment other than parental reassurance may be necessary. Watchful waiting, close follow-up with a feeding diary, and weekly weight checks have no adverse effects and should be considered first line for mild laryngomalacia with stridor when there is no evidence of obstruction, oxygen desaturation, cyanosis, feeding problems, or weight gain issues. Although these neonates may be very noisy and stridorous, parental reassurance is all that is necessary. This can represent a significant clinical challenge, but further treatment may not be necessary.

Conservative measures such as positioning and feeding changes rarely have adverse effects and should be considered before pharmacologic or surgical options are pursued.

Gastric acid suppression is thought to have few adverse effects, but gastrointestinal upset and motility issues are most common.

Supraglottoplasty carries a not insignificant risk of postoperative aspiration. Aspiration should be considered when persistent or severe coughing/choking episodes are associated with feeding or spitting up. A barium swallow test should be performed in all children with suspected aspiration. Thickening of feedings (with barium swallow confirmation of its effectiveness) should be the first line of therapy for mild postoperative aspiration.

When significant or severe aspiration follows supraglottoplasty, temporary nasogastric tube feeding should be instituted. Persistent aspiration may require gastrostomy tube placement. When the above is accompanied by GERD, Nissan fundoplication should be considered.

What are the possible outcomes of this disease?

Laryngomalacia is largely self-limited and infrequently requires any treatment other than parental reassurance. It is estimated that fewer than 10% of patients require medical or surgical intervention. The majority of patients experience spontaneous resolution of stridor by 12-18 months. This likely corresponds with normal development and a more sustained upright waking posture. Standing and the subsequent decrease in normal physiologic GER is also thought to play a role. Treatment beyond 12-18 months is rare and primarily associated with other congenital anomalies or developmental delays.

What is the evidence?

Gandhi, S, Thekedar, P, Mishra, P. “Role of transoral CO2 laser surgery for severe pediatric laryngomalacia”. Eur Arch Otorhinolaryngol. vol. 268. 2011. pp. 1479-83.

Rastatter, JC, Schroeder, JW, Hoff, SR. “Aspiration before and after supraglottoplasty regardless of technique”. Int J Otolaryngol. vol. 2010. 2010.

Thevasagayam, M, Rodger, K, Cave, D. “Prevalence of laryngomalacia in children presenting with sleep-disordered breathing”. Layrngoscople. vol. 120. 2010. pp. 1662-6.

Richter, GT, Thompson, DM. “The surgical management of laryngomalacia”. Otolaryngol Clin North Am. vol. 41. 2008. pp. 837-64.

Durvasula, VS, Lawson, BR, Bower, CM, Richter, GT. “Supraglottoplasty outcomes in neurologically affected and syndromic children”. JAMA Otolaryngology-Head & Neck Surgery. vol. 140. 2014. pp. 704-11.

Tanphaichitr, A, Tanphaichitr, P, Apiwattanasawee, P, Brockbank, J, Rutter, MJ, Simakajornboon, N. “Prevalence and risk factors for central sleep apnea in infants with laryngomalacia”. Otolaryngology – Head & Neck Surgery. vol. 150. 2014. pp. 677-83.

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