Tracheomalacia (TM) refers to diffuse or segmental tracheal weakness . Tracheobronchomalacia (TBM) exists when the weakness extends into one or both mainstem bronchi. Both conditions result in exaggerated luminal narrowing during expiration and widening during inspiration [2-5]. The airway narrowing can be extensive.
We refer to TM and TBM collectively as TM in this review, since the conditions manifest similarly and the terms are frequently used interchangeably in practice. We distinguish between the disorders only when necessary.
The classification, epidemiology, histopathology, natural history, symptoms, diagnosis, and treatment of TM are reviewed here. Tracheomalacia in children is discussed separately. (See "Congenital anomalies of the intrathoracic airways and tracheoesophageal fistula".)
Several classification systems exist for TM:
- TM can be classified according to the appearance of the trachea. Patients who have anteroposterior tracheal narrowing are said to have crescent (ie, scabbard shape) TM (figure 1), while patients who have lateral tracheal narrowing are said to have saber-sheath (ie, fissure shape) TM.
- TM can be classified according to its distribution, as either segmental or diffuse. This is particularly useful for guiding therapy.
- TM can be classified as congenital (ie, primary) or acquired (ie, secondary) (table 1) [6,7]. Acquired TM is more common than congenital TM in adults.