Subglottic stenosis can present as stridor that is frequently biphasic (on both inspiration and expiration). However, the stridor is usually more prominent on inspiration. With increasing respiratory effort, the stridor becomes louder. Very small infants may not be able to breathe with enough force to generate a sound. Subglottic stenosis may also be associated with a barky cough similar to that noted with croup. Respiratory infections can cause subglottic edema, exacerbating the clinical manifestations of subglottic stenosis.
Definitive diagnosis requires endoscopic evaluation, either by flexible or rigid bronchoscopy.
Mild subglottic stenosis can be managed conservatively and may improve sufficiently with airway growth alone. More severe cases require surgical intervention. Depending on the nature of the lesion, endoscopic laser treatment may be effective. Other surgical options include tracheoplasty and cricoid split procedures. A tracheostomy tube may be required to bypass the subglottic space until the airway is patent enough to allow adequate airflow.
Upper airway mass lesions are relatively uncommon. The most common laryngeal tumor in childhood is the hemangioma, which usually presents before 6 months of age. (See Chapter 194.) Subglottic lesions produce asymmetrical narrowing of the subglottic space on AP radiographs of the larynx, but definitive diagnosis requires endoscopy. If the obstruction is severe, then a tracheostomy tube may be needed until the lesion spontaneously involutes or improves with therapy.
Laryngeal webs are the result of failed recanalization of the glottic airway in utero, whereas laryngeal cysts typically occur as a consequence of airway trauma (intubation). Both can produce biphasic stridor and are best identified by bronchoscopy. Foreign body should be considered in any infant or child capable of ingesting small objects who develops acute onset of stridor.
Juvenile laryngeal papillomatosis is a rare condition of benign tumors caused by human papillomavirus (HPV-6 and HPV-11) acquired at birth from maternal genital warts. Clinical manifestations usually start in infancy and include biphasic stridor and hoarse voice/cry. The lesions are most commonly located in the larynx, but they can spread distally into the trachea, large bronchi, and even to the lung parenchyma. Treatment options, which are limited and rarely curative, include laser therapy and interferon. Tracheostomy may be required to ensure an adequate airway, but should be avoided if possible as reports suggest a related seeding of the distal airways with tumor.
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Vocal cord paralysis is an important cause of laryngeal dysfunction. Paralysis may be unilateral or bilateral and is more often caused by damage to the recurrent laryngeal nerve than by a central lesion. The left recurrent laryngeal nerve passes around the aortic arch and is more susceptible to damage than the right laryngeal nerve. Peripheral nerve injury may be caused by trauma (neck traction during delivery of infants or thoracic surgical procedures) and mediastinal lesions. Central causes include Arnold-Chiari malformation (meningomyelocele), hydrocephalus, and intracranial hemorrhage.
Vocal cord paralysis presents as biphasic stridor and alterations in voice and cry, including a weak cry (in infants), hoarseness, and aphonia. Children with vocal cord paralysis are at risk for aspiration, often manifested as coughing/choking with drinking and coarse airway sounds audibly and by auscultation.