<unk>  refers to abnormal narrowing of the central air passageways. This can occur at the level of the larynx, trachea, carina or main bronchi. In a small number of patients narrowing may be present in more than one anatomical location.
Laryngotracheal stenosis
Tracheobronchomalacia
Laryngomalacia
Subglottic stenosis
Tracheal deviation
Tracheoinnominate fistula
Tracheomalacia
Glossoptosis