الفهرس 
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Abstract
Stridor is a loud, harsh, and high-pitched respiratory sound. It is usually heard on inspiration due to partial obstruction of the airway (usually extra-thoracic—that is, in the trachea, larynx, or pharynx). Stridor can occur on expiration in severe upper airway obstruction but usually indicates tracheal or bronchial obstruction (intra-thoracic). Biphasic stridor suggests subglottic or tracheal obstruction. Difficulties at the level of the larynx are commonly associated with stridor or noisy breathing. Some congenital anomalies present immediately with airway distress while others are asymptomatic or discovered later in infancy or childhood as feeding and growing difficulties. Supraglottic anomalies including laryngomalacia, bifid epiglottis, saccular cyst, and laryngeal cleft affect the airway at the level of the epiglottis through the ventricle, which sits immediately superior to the vocal folds. Laryngomalacia is the most common cause of stridor in newborns, affecting 45–75% of all infants with congenital stridor. Most infants with laryngomalacia will have mild symptoms and a benign disease course that resolves by the age of 12 to 24 months; however, it is important to recognize that not all cases of laryngomalacia have a benign course.