What is the distinguishing feature between laryngomalacia and a vascular ring?

The distinguishing feature between laryngomalacia and a vascular ring is the type of stridor associated with each condition.

Laryngomalacia, which is a common cause of stridor in infants, typically presents with a high-pitched, noisy breathing that is more pronounced when the infant is in a supine position or during feeding. This stridor is characterized as being intermittent and often improves with positioning or during sleep.

In contrast, a vascular ring can cause stridor as well, but it usually presents differently. The stridor associated with a vascular ring tends to be more persistent and is often accompanied by additional symptoms such as respiratory distress, feeding difficulties, or choking due to the compression of the trachea and esophagus by the vascular structure.

The other differentiating factors, such as age of onset, severity of symptoms, and response to hypoxia, do play a role in the clinical picture of each condition but are not as definitive in distinguishing between laryngomalacia and a vascular ring as the characteristics of the stridor itself.