DefinitionStridor is an abnormal, high-pitched, musical breathing sound caused by a blockage in the throat or voice box (larynx). It is usually heard when taking in a breath.See also: WheezingAlternative NamesBreathing sounds - abnormal; Extrathoracic airway obstructionConsiderationsChildren are at higher risk of airway blockage because they have narrower airways than adults. In young children, stridor is a sign of airway blockage and must be treated right away to prevent total airway obstruction.The airway can be blocked by an object, swelling of the tissues of the throat or upper airway, or spasm of the airway muscles or the vocal cords.Common CausesCommon causes of stridor include:Abscess on the tonsilsAirway injuryAllergic reactionCroupDiagnostic tests such as bronchoscopy or laryngosc