Laryngomalacia (Congenital Flaccid Larynx)

Epidemiology

Laryngomalacia (LM) is the most common congenital laryngeal abnormality and accounts for 60% of laryngeal problems in the newborn. It is the most common cause of stridor in infants. The condition usually presents within the first few weeks of life. LM is frequently associated with other coexistent abnormalities of the larynx. There is no reported gender predeliction for LM.

Clinical Findings

Patients with LM present with inspiratory stridor. Stridor is seldom present at birth but usually starts within the first few days to weeks of life. The stridor is of variable intensity and is aggravated with crying, feeding, or other periods of excitement or activity. Stridor is also worse when patients lie on their back with their head flexed. Patients are acyanotic with a normal cry. LM is rarely associated with dyspnea or difficulty swallowing.

Pathology

LM appears to be related to flaccidity and incoordination of the soft tissue and cartilages of the supraglottic larynx. The exact cause of LM is currently under debate. Some authors feel certain anatomic abnormalities predispose patients to develop LM, including (1) an elongated epiglottis that curls upon itself (omega-shaped epiglottis), (2) fore-shortened aryepiglottic folds, and (3) bulky arytenoids, which tend to prolapse into the airway with inspiration. Other investigators feel that LM is caused by poor neuromuscular control resulting in inadequate muscular support of the cartilaginous framework of the epiglottis with increased compliance of the supraglottic tissues. This may be due to delayed development of the neuromuscular pathways controlling the airway in affected patients.