Stridor

What is stridor? Stridor is the sound produced by turbulent flow of air through a narrowed segment of the respiratory tract. It is a sign of airway obstruction in a child. It typically originates from the larynx (voice box) or trachea (windpipe). The larynx functions as a passage for breathing, an organ of communication, and as a protective valve to prevent foreign objects including food and water from entering the lungs. Infections or abnormalites of the larynx can produce symptoms and signs of airflow obstruction, altered phonation, and/or feeding difficulty.

What are the causes of stridor? Congenital anomalies of the larynx, trachea, and bronchial tree, infectious conditions of the respiratory tract, vocal cord paralysis, trauma, and neoplasms (tumors) of the airway can all produce stridor.

How is stridor evaluated? Stridor is most appropriately evaluated by an otolaryngologist (ENT surgeon), who have special training and equipment for such evaluations. After obtaining a detailed history, the doctor will usually pass a thin flexible tube which houses a light and a telescope through the child’s nose or mouth and examine the interior of the upper aerodigestive tract (picture). Then, depending on the findings, the physician will either arrive at a definitive diagnosis, or request an imaging study (XRays or scans) to confirm it. At times, it may be required to further evaluate the whole airway of the child in detail under a general anesthetic to confirm initial findings and rule out lesions elsewhere in the respiratory tract. A pediatric gastroenterologist and/or a pulmonologist may also be consulted to help plan appropriate management.

Should all stridor be evaluated? Stridor is a sign of some type of problem, and is not a diagnosis itself. It could be due to floppy laryngeal structures (called laryngolmalacia), which usually disappears as the child grows, or the initial manifestation of a life-threatening event. Proper management is possible only after a diagnosis has been established.

What is the most common cause of stridor in an infant? Laryngomalacia is the most frequent cause of stridor in infants. It is a result of flaccidity of laryngeal structures and tissues causing them to collapse into the airway. The incidence of laryngomalacia as a cause of stridor in children has been reported as being between 50% and 75%.