Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature.

Thomson in 1892 made this observation: "The infant who appears normal in all other respects is noticed shortly after birth to have noisy breathing. The noise consists of a croaking sound accompanying inspiration, which rises to a high pitched crow when a longer or more vigorous breath is taken. The stridor increases in loudness during the first few months, gradually lessens and disappears during the course of the second year." This description is still very appropriate today.

Thompson coined the term "congenital laryngeal stridor" for this entity however it was actually first described by Rillet and Barthez who were the first to recognize and this group of infants with self-limited stridor. In 1885 Lees described a congenital malformation of the larynx in which the epiglottis curled inward. Thompson and his colleague Turner performed experiments demonstrating passive prolapse of the larynx. Holinger introduced the term "laryngomalacia" in 1960. Belmont and Grundfast in their landmark article (see bibliography) promoted a return to the term "congenital laryngeal stridor" but this is felt to be a poor term since it is not the only cause of neonatal stridor.

When evaluating the infant with respiratory symptom one must first determine whether the problem is one of ventilation or of oxygenation. Stridor suggests a ventilatory disorder. The Bernoulli principle states that the pressure gradient across a given segment of air flow in a hollow structure is related to the diameter or cross-sectional area of that structure. Upper airway patency depends on active muscle contraction. Pressure sensors in the larynx sense negative airway pressures and stimulate active dilation of the larynx in preparation for inspiration. Because of the intrinsic structure of the larynx, at any given glottic aperture the resistance to airflow is greater in inspiration than in expiration. When the airway is narrowed, stridor results from the rapid, turbulent air flow through that narrowed segment.

The differential diagnosis for chronic or persistent neonatal stridor is vast and encompasses lesions throughout the airway tract. The history and physical can help to identify the site of the lesion because the specific symptomatology is often related to the site of obstruction. Congenital anomalies account for 87% of these lesions. Overall, laryngomalacia accounts for 60% of cases of chronic laryngeal stridor. Other diagnoses that should be entertained include: craniofacial anomalies, choanal atresia, encephalocele, turbinate hypertrophy, laryngomalacia, vocal cord paralysis (unilateral & bilateral), congenital or acquired subglottic stenosis, laryngeal webs, cysts or clefts, papillomatosis, GER (gastroesophageal reflux), tracheomalacia, vascular ring, mediastinal masses and, last but not least, foreign bodies.

It is especially important to know the differential diagnosis for stridor in the neonate because 17.5% (12- 27%) of patients with stridor and respiratory symptoms have two or more unrelated airway lesions. Gonzales performed a retrospective analysis of infants undergoing DL&B for stridor or airway distress. His team found 27% of patients with laryngomalacia had synchronous airway lesions and half of these were below the vocal folds. The finding of cyanosis was significantly associated with a significant synchronous lesion and the lesion may not be apparent on flexible laryngoscopy. In addition, multiple authors have written about the concurrent finding of GER in some of these patients. GER has been documented in up to 80% of patients with laryngomalacia. Evaluation and treatment of this should be considered in symptomatic patients. Failure of surgical correction has been attributed to uncontrolled reflux in two studies.

Following the history and physical exam, the next step in evaluation of an child with congenital stridor is flexible laryngoscopy to provide an assessment of the laryngeal anatomy and a dynamic view of laryngeal function and vocal cord motion. Operative direct laryngoscopy and bronchoscopy may also be indicated. This should always be done utilizing spontaneous ventilation, with the laryngoscope blade in the vallecula. This minimizes distortion and provides a better evaluation of the dynamic larynx. One should also use the telescope for magnification, otherwise one is at risk for missing abnormalities. In the appropriate situations other diagnostic test are indicated: AP & Lateral neck radiographs can be especially helpful in identifying epiglottitis, tracheitis and subglottic stenosis and a chest radiograph can help assess for foreign body aspiration, cardiac and pulmonary disorders. Esophageal barium swallow or fluoroscopy may also be helpful in the evaluation.

The stridor in laryngomalacia is caused by obstruction at the level of the supraglottic when epiglottic and arytenoid tissues prolapse into the rima glottidis with inspiration. Not much is known about the exact cause. There are two schools of thought. Those favoring a structural etiology stipulate that the anatomic findings of a tubular epiglottis, shortened A-E folds and large arytenoids in these patients cause a narrowing of the supraglottic and the resultant higher airway pressures forces collapse of these tissues into the glottic opening. This theory is supported by histologic exams which demonstrate normal cartilage in autopsy specimens. Others believe that a neurogenic etiology is responsible for this disorder. Neuromuscular immaturity, hypofunction or incoordination is believed to cause flaccidity of the supraglottic structures. Supporters of this theory point to studies which show an association of other neurologic disorders including central apnea, hypothermia and GER in some patients. In addition, experimental evidence has demonstrated medial prolapse of the larynx in denervated larynges in animals and in addition there are many reported cases of acquired laryngomalacia following closed head injury.

Laryngomalacia is generally considered to be a congenital lesion of infants, however a mechanistically similar identity has been described in adults following head injury, laryngeal trauma or surgery and in patients with neuromuscular disorders. The classic presentation of laryngomalacia is onset of inspiratory stridor early after birth; infants usually have a normal cry, are more symptomatic in the supine position and may have more difficulties with feeding. Usually laryngomalacia is congenital but it may be acquired by brain injury, laryngeal trauma surgery or may be associated with neuromuscular disorders. In addition it has been described following T&A for sleep apnea and has also been reported to be inherited in rare cases.

Although usually a benign disorder, complications of do occur. Feeding difficulties, obstructive sleep apnea, bradycardias, cor pulmonale, failure to thrive and pectus excavatum (due to persistent retractions) can all be seen in severe cases. These patients require more frequent hospitalization and intubation with URI than average child. The natural history in most patients is for spontaneous recovery, however because of frank airway obstruction or other complications 10-15% of babies require surgical intervention to improve their airway. Intellectual compromise has not been statistically associated with this disorder as was previously thought.

Tracheostomy has been the standard treatment for upper airway obstruction for over a century. With the development of laryngoscopy and endoscopic techniques more sit specific treatments could be developed. In the early twentieth century a snare used to amputate a portion of the epiglottis. Following this, hypmandibulopexy airway utilized in an attempt to improve the airway by suspending the hyoepiglottic ligament to the mandible. Contemporary surgeons began looking for alternative treatments for this entity. In general these methods addressed the three anatomic abnormalities exhibited by these patients: the floppy epiglottis, the redundant arytenoid tissue and the shortened aryepiglottic folds. Various forms of aryepiglottic fold excision, laser division and microsurgical trimming was performed. Currently popular is the CO2 laser supraglottoplasty technique in which the aryepiglottic folds are divided and the redundant arytenoid tissue is vaporized.

A four-month-old Hispanic male infant presented to the Texas Children's Hospital with respiratory distress, wheezing, fever, and slow weight gain. His past medical history was significant for recurrent upper respiratory tract infections and a prior history of hospitalization for pneumonia at six weeks of age. On evaluation he was found to have a right lower lobe pneumonia and was admitted for IV antibiotics. On physical examination he was noted to exhibit inspiratory stridor that did not resolve as he cleared his pulmonary infection. He was evaluated by the Otolaryngology service and flexible laryngoscopy demonstrated a tubular epiglottis, redundant mucosa over the arytenoids, and prolapse of the supraglottic with inspiration, all diagnostic for laryngomalacia.

Because of his significant respiratory symptomatology he underwent an airway evaluation under spontaneous ventilation anesthesia. Laryngomalacia was confirmed and he was also found to have mild tracheomalacia associated with an extrinsic vascular compression consistent with a vascular anomaly. CO2 laser supraglottoplasty was performed to manage the laryngomalacia. He was evaluated by the Cardiovascular and Cardiology services and a double aortic arch was confirmed. Immediately postoperatively he did well; however, two weeks later he was again admitted to the hospital with increased stridor and respiratory distress. This hospital visit he underwent revision supraglottoplasty, cardiac catheterization, and division of his vascular ring. Since that time he has done well with minimal symptomatology except for a visit at eight months of age for stridor associated with an upper respiratory infection.

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