<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A congenital or acquired abnormality of the wall of the trachea. In congenital cases, there is lack of rigidity in the cartilage of the tracheal wall. In acquired cases, the cartilage of the tracheal wall is degenerated, secondary to tracheostomy or prolonged presence of a breathing tube, or as a complication of a tracheoesophageal fistula surgical repair. Symptoms include stridor, noisy breathing, and upper respiratory infections.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>