Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter VIII.10. Congenital Airway Problems
Winona K. Lee, MD
June 2002

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This is a 4 week old male who has been brought to your office with a one week history of "noisy breathing." His parents note that his noisy breathing is worse when they lay him down or with crying. It is most noticeable when he takes a breath in. There has been no history of fever, coughing, runny nose, change in his cry, apnea, or feeding difficulties. He has been gaining weight appropriately. Prenatal course was uneventful and he was delivered at 38 weeks gestation by spontaneous vaginal delivery without complications. Family History is unremarkable.

Exam: VS T 37.0, P 120, RR 48, oxygen saturation 98% in room air. Weight and height are at the 50%ile. He is alert, active, in no acute distress. There is audible inspiratory stridor noted in the supine position, which is improved with extension of his neck. His anterior fontanel is soft and flat. His eyes and ears are normal. No nasal flaring is visible and his nares appear patent. His throat shows no erythema or lesions. His lips are moist and pink. There are no retractions or pectus abnormalities. His lungs are clear to auscultation throughout once the stridor clears with airway repositioning (no wheezes or rales). Aeration is good. He has noisy referred upper airway sounds when he is supine with his neck flexed. His heart is regular without murmurs. His color, perfusion, capillary refill and pulses are good.

He is referred to ENT for a flexible fiberoptic laryngoscopy, which confirms the diagnosis of mild laryngomalacia. His status is monitored clinically. He continues to feed well and gain weight appropriately. All his symptoms resolve by 18 months of age.


Laryngomalacia

Laryngomalacia is the most common congenital anomaly of the larynx. It represents 60% of all congenital laryngeal anomalies (1). Males are affected twice as often as females. It is generally self-limiting, however, severe cases of laryngomalacia can lead to failure to thrive and life-threatening apnea (2).

The exact etiology is unclear, however, theories include maldevelopment of the cartilaginous structures of the airway and immature neuromuscular control. The epiglottis is derived from the 3rd and 4th brachial arches. An overgrowth of the 3rd arch results in an elongated and laterally extended epiglottis (1). Neuromuscular immaturity may contribute to the prolapse of the arytenoids observed in laryngomalacia; however; there is no increase in the incidence of laryngomalacia in premature infants with classic hypotonicity (1).

Symptoms of laryngomalacia are typically absent at birth, arising at 2 to 4 weeks of age. Common symptoms include inspiratory stridor, which is worsened with supine position and with agitation or excitement (3). Feeding difficulties, exacerbated by gastroesophageal reflux, may occur due to the increased negative intrathoracic pressure created by a partially obstructed airway (2). Patients have a normal cry and rarely present with respiratory distress or cyanosis. Rare complications include chest deformities, obstructive apnea, and failure to thrive (1).

The classic history will guide one to the diagnosis of laryngomalacia; however, diagnosis is confirmed by flexible laryngoscopy while the patient is awake (3). Laryngoscopy typically reveals an elongated and laterally extended (omega shaped) epiglottis that falls posteriorly on itself on inspiration. Visualization also reveals inward collapse of the aryepiglottic folds (cuneiform cartilages) on inspiration and bulky arytenoids that prolapse on inspiration (1).

Management is expectant with simple reassurance for parents. Patients are observed for adequate growth. Symptoms of gastroesophageal reflux should be monitored since this can aggravate symptoms and can be improved with anti-reflux precautions. In patients with failure to thrive or obstructive apnea, surgical interventions such as epiglottoplasty (dividing the aryepiglottic folds and trimming the epiglottis) may be required (2).

Vocal Cord Paralysis (also known as Vocal Fold Paralysis)

The second most common congenital anomaly of the larynx is vocal cord paralysis, accounting for 20% of laryngeal lesions. The paralysis can be unilateral or bilateral. In general, bilateral paralysis is usually due to a central nervous system problem, while unilateral paralysis is typically caused by an injury to the peripheral nervous system (2). Specific causes of vocal cord paralysis include meningomyelocele with Arnold-Chiari malformation, hydrocephalus, birth trauma, and surgical trauma (4).

Infants with vocal cord paralysis may present at birth or within the first few weeks of life. Symptoms include a weak or breathy cry, noted typically in unilateral vocal cord paralysis. Patients may also present with inspiratory or biphasic stridor, aspiration or feeding difficulties, and occasionally respiratory compromise (3).

The diagnosis of vocal cord paralysis can be made at the bedside with direct visualization of the vocal cords using a laryngoscope (direct laryngoscopy), but is confirmed by rigid endoscopy under anesthesia while the patient is breathing spontaneously. Alternatively, flexible laryngoscopy while the patient is awake to assess vocal cord mobility can be used. Imaging may be utilized to rule out associated CNS lesions (4).

Initial management includes stabilization of the airway and support for feeding and nutrition (3). In most cases of unilateral vocal cord paralysis, no intervention is needed since compensation by the opposite vocal cord occurs over time and most cases resolve within the first few weeks of life. In bilateral vocal cord paralysis, tracheostomy is generally required to stabilize the airway. Bilateral vocal cord paralysis secondary to a neurological problem often improves once the neurological problem is addressed. In cases of idiopathic bilateral vocal cord paralysis, symptoms may spontaneously resolve by age of 2. If not, it is unlikely to do so. Surgical methods have had moderate success in improving the airway and promoting decannulation (removal of tracheostomy) by age 4 to 5 years (2).

Congenital Subglottic Stenosis

Congenital subglottic stenosis is the third most common congenital anomaly of the larynx. It accounts for 15% of all cases. Males are affected twice as often as females (5). Congenital subglottic stenosis is usually associated with a small or malformed cricoid cartilage with or without thickening of the underlying submucous layer.

Patients with subglottic stenosis may be asymptomatic until an upper respiratory infection causes further narrowing of the airway. The patient may present with biphasic stridor and a barking cough may be noted. Many patients are diagnosed with recurrent croup prior to a final diagnosis of subglottic stenosis. With severe subglottic stenosis, patients will present with dyspnea and marked suprasternal and subcostal retractions. The patient's cry remains unaffected (2).

A history of recurrent croup may support the diagnosis of congenital subglottic stenosis. Subglottic narrowing may be noted on plain lateral and AP x-rays and the diagnosis is made with rigid bronchoscopy. The length and diameter of the stenosis is measured and congenital subglottic stenosis is diagnosed when the lumen diameter is less than 4 mm in a term infant or less than 3 mm in a preterm infant (1).

In the majority of patients with subglottic stenosis, respiratory problems resolve with growth of the child. However, endotracheal intubation and tracheostomy may be needed in patients with significant airway compromise. Decannulation by age 3 to 4 years is usually possible when the subglottic space widens. Laryngeal reconstruction to enlarge the lumen of the stenotic airway has proven successful in severe cases of congenital subglottic stenosis (4).

Tracheomalacia

In tracheomalacia, the trachea lacks firmness, causing the anterior and posterior walls to come together during respiration, decreasing the tracheal lumen. Tracheomalacia occurs in 2 forms: primary and secondary. Primary tracheomalacia is rare and is caused by a congenital deformity of the supporting tracheal rings. Secondary tracheomalacia is due to external compression from lesions such as vascular anomalies (e.g., vascular ring), tumors or hemangiomas. It can also result from surgical intervention such as tracheoesophageal fistula repair (5).

Patients with tracheomalacia can present with inspiratory or expiratory stridor, wheezing, and a barking cough. Dramatic "dying spells", in which the patient undergoes reflex apnea progressing to cardiac arrest, can also occur. Patients can also present with recurrent pneumonitis secondary to chronic obstruction and difficulty clearing bronchial secretions (5).

Direct endoscopy is the only reliable method to diagnosis tracheomalacia. Both types of tracheomalacia are typically self-limited, but in severe cases a tracheostomy may be needed to stent the trachea during development. In the secondary form, correction of the underlying lesion to alleviate external compression is associated with a good outcome (3).

Congenital airway anomalies must be considered when evaluating stridor of infancy. The key is to separate life-threatening conditions from those which are self-limited. With a thorough history and physical examination, one can establish the initial diagnosis, make the appropriate referral to the ENT specialist, and support the infant until a diagnosis is confirmed.


Questions

1. What is the most common cause of laryngeal anomalies in infants?

2. Classically, the stridor in laryngomalacia is:
a) inspiratory . . . . b) expiratory . . . . c) biphasic

3. The secondary form of tracheomalacia is usually due to:
. . . . . a. a congenital deformity of the supporting tracheal rings.
. . . . . b. an extrinsic compression such as a vascular anomaly.
. . . . . c. surgical intervention such as tracheoesophageal fistula repair.
. . . . . d. b and c.
. . . . . e. all of the above.

4. Anatomically, congenital subglottic stenosis is usually associated with what other airway malformation?

5. As the second most common laryngeal anomaly, vocal cord paralysis accounts for what percentage of laryngeal lesions?

6. A child with a diagnosis of recurrent croup may suggest which airway anomaly?

7. Most cases of laryngomalacia resolve by what age?
. . . . . a. 6-12 months old
. . . . . b. 12-18 months old
. . . . . c. 18-24 months old
. . . . . d. 24-36 months old

8. In general, bilateral vocal cord paralysis can be attributed to a _____nervous system problem, while unilateral vocal cord paralysis is usually caused by an injury to the ___nervous system.


References

1. Tewfik TL, Sobol SE. Congenital Malformations, Larynx. eMedicine Journal 2002;3(2).

2. Cotton RT, Prescott CAJ. Chapter 30 - Congenital Anomalies of the Larynx. In: Cotton RT, Meyer III CM (eds). Practical Pediatric Otolaryngology. 1999, Philadelphia: Lippincott-Raven, pp. 497-514.

3. Hughes CA, Dunham ME. Chapter 47 - Congenital Anomalies of the Larynx and Trachea. In: Wetmore RF, Muntz HR, McGill TJ (eds). Pediatric Otolaryngology: Principles and Practice Pathways. 2000, New York: Thieme, pp. 775-786.

4. Chapter 28 - Paediatric airway disease. In: Burton M (ed). Hall and Colman's Diseases of the Ear, Nose, and Throat, fifteenth edition. 2000, New York: Churchill Livingstone, pp. 187-195.

5. Zalzal GH, Cottton RT. Chapter 107 - Glottic and Subglottic Stenosis. In: Cummings CW (ed). Otolaryngology - Head and Neck Surgery, second edition. 1993, Chicago: Mosby Year Book, pp. 1981- 2000.


Answers to questions

1. Laryngomalacia

2. a. inspiratory

3. d. b and c

4. small or malformed cricoid cartilage

5. 20%

6. congenital subglottic stenosis

7. c. 18 to 24 months old

8. central, peripheral


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