It’s perplexing to many of us as to why some infants present with mild inconsequential expiratory stridor that gets better over time, others have swallowing difficulty and are considered to have moderate disease, and then there are those that are severe and have cardiopulmonary complications like hypoxia, chronic cyanosis, and significant stridor, said Dana M. Thompson, MD, in discussing her award-winning thesis. Dr. Thompson is Associate Professor of Otolaryngology at Cincinnati Children’s Hospital Medical Center (Ohio).
Explore this issue:July 2006
Another perplexing aspect of laryngomalacia is the association of gastroesophageal reflux disease (GERD). This has been underexplored, but it’s intuitive to those of us who have managed these children that reflux does have a role, Dr. Thompson said. The one thing that we do know is that laryngeal tone is weak, but why it’s weak is unknown.
Diverse Theories of Etiology
Among the theories that have been introduced since the disease was first described in the 19th century are the anatomic theory, which proposes abnormal anatomic placement of the supraglottic laryngeal tissue, and the cartilaginous theory, which suggests abnormal cartilage formation.
However, the neurologic theory of disease etiology for laryngomalacia is probably the one that is best supported in the literature, Dr. Thompson said, noting past studies suggesting that up to 20% of laryngomalacic children had neurologic disease.
The other fact is that we know, in adults, a central nervous system insult, particularly at the brain stem, can result in the findings of acquired laryngomalacia, she said. Also, sedative medications can lead to a laryngomalacic-like state and symptoms.
Role of Reflux
Apart from the disease etiology, a key factor is laryngeal adductor reflux, which is a vaguely mediated reflux responsible for laryngeal tone, but also has additional contributions for airway protection and swallowing function.
This is a very complex, neurologically integrated reflux with both peripheral and central components, Dr. Thompson said. This is the reflux that is responsible for laryngeal tone. What happens when this reflux goes awry is that you get abnormal sensorimotor integration, and this can occur either at the peripheral level or at the efferent level.
In looking at these and a variety of other considerations, Dr. Thompson hypothesized that infants with laryngomalacia-particularly those with moderate and severe disease-exhibit elevated thresholds, which lead to the signs and symptoms of laryngomalacia, including aspiration, breathing problems, apnea, and the inability to efficiently swallow or clear stimulus.
So the goal of this study was to further elucidate disease etiology of laryngomalacia by exploring the laryngopharyngeal sensory-testing aspect of integration of airway patency and tone, she said. Also, because there is such a wide spectrum of disease severity, we wanted to try and understand what factors may influence the disease spectrum, so we explored medical comorbidities, demographic characteristics, and disease presentation.
Altered Reflexes Play Role in Etiology
Dr. Thompson and her colleagues looked at 201 infants with laryngomalacia. The disease was confirmed by flexible laryngoscopy and sensory testing. Patients were divided into three groups based on level of disease severity-mild, moderate, and severe-and were followed prospectively until symptoms resolved or subjects were lost to follow-up. Sensorimotor integrative function of the larynx was evaluated by laryngopharyngeal sensory testing of the laryngeal adductor reflex. Medical records were retrospectively reviewed for comorbidities.