Abnormal sensorimotor integrative function of the larynx in congenital laryngomalacia: a new theory of etiology.
Laryngomalacia is an enigmatic disease in which laryngeal tone is weak, resulting in dynamic prolapse of tissue into the larynx. Sensorimotor integrative function of the brainstem and peripheral reflexes are responsible for laryngeal tone and airway patency. The goal of this study was to elucidate the etiology of decreased laryngeal tone through evaluating the sensorimotor integrative function of the larynx. The secondary goal was to evaluate factors and medical comorbidities that contribute to the wide spectrum of symptoms and outcomes. Prospective and retrospective collection of evaluative data on infants with congenital laryngomalacia at two tertiary care pediatric referral centers. Two hundred one infants with laryngomalacia were divided into three groups on the basis of disease severity (mild, moderate, severe). Patients were followed prospectively every 8 to 12 weeks until symptom resolution or loss to follow-up. Sensorimotor integrative function of the larynx was evaluated in 134 infants by laryngopharyngeal sensory testing (LPST) of the laryngeal adductor reflex (LAR) by delivering a duration- (50 ms) and intensity- (2.5-10 mm Hg) controlled air pulse to the aryepiglottic fold to induce the LAR. Medical records were retrospectively reviewed for medical comorbidities. The initial LPST was higher (P < .001) in infants with moderate (6.8 mm Hg) and severe disease (7.4 mm Hg) compared with those with mild disease (4.1 mm Hg). At 1, 3, and 6 months, infants with moderate and severe disease continued to have a higher LPST compared with those with mild disease. At 9 months, the LPST decreased in all subjects (3.1-3.5 mm Hg, P = .14), which also correlated with symptom resolution. Neurologic, genetic, and cardiac diseases were more common in infants with severe disease (P < .001). Gastroesophageal reflux disease (GERD) and feeding problems more common in those with moderate and severe disease (P < .001). Apgar scores were lower in those with severe disease (P < .001). Most symptoms resolved within 12 months of presentation. Those with GERD benefited from treatment. Supraglottoplasty resulted in few complications. Multiple comorbidities (>3) influenced the need for tracheotomy. Laryngeal tone and sensorimotor integrative function of the larynx is altered. The degree of alteration correlated with disease severity, indicating that factors that alter the peripheral and central reflexes of the LAR have a role in the etiology of signs and symptoms of laryngomalacia. GERD, neurologic disease, and low Apgar scores influenced disease severity and clinical course, explaining the spectrum of disease symptoms and outcomes. Sensorimotor integrative function improved as symptoms resolved.