The stridor improves with neck extension, differentiating from laryngomalacia which is relieved by prone or upright positioning, and will not be relieved with corticosteroids or epinephrine, unlike croup.
The stridor improves when the neck is extended, a feature that differentiates it from laryngomalacia, which is improved by lying down or sitting up but not with steroids or epinephrine like croup.