Idiopathic subglottic stenosis (ISS) refers to narrowing of the upper trachea of unknown cause. The disease is rare, with an estimated incidence of 1 per 400,000 person-years. ISS accounts for approximately 19 percent of patients with laryngotracheal stenosis, with the majority having an identifiable cause such as an iatrogenic injury, neck or throat trauma, or an inflammatory connective tissue disease. The exact pathogenesis of ISS is unknown, but disordered inflammation, aberrant immune response to infection and gastroesophageal reflux are thought to play a role.

Patients with ISS are nearly universally women, and most are premenopausal. The most common presenting symptoms are progressive dyspnea and dysphonia; patients also can have stridor, cough or difficult-to-expectorate sputum.