How to differentiate asthma from vocal cord dysfunction (VCD) in a young athlete with exercise-induced dyspnea?

A 22-year-old female track runner presents with recurrent episodes of inspiratory stridor, throat tightness, and dyspnea during intense exercise. Spirometry is normal between episodes. She has been on inhaled corticosteroids without improvement. How do we differentiate VCD from exercise-induced bronchoconstriction, and what is the diagnostic gold standard? What are the management options for VCD?