Chronic rhinosinusitis, or CRS, is a condition that affects an estimated
37 million Americans. The National Institute for Health Statistics estimates that CRS is one of the most common chronic conditions in the United States.

CRS is defined as a chronic inflammatory disease of the nasal and associated mucosa that persists for greater than three months. It results in symptoms that include nasal congestion, difficulty breathing, and in some patients, a decreased sense of smell. Long-term consequences include extensive mucosal thickening in the nasal cavity and the formation of nasal polyps.

CRS differs from acute rhinosinusitis (which last three to four weeks) not only by its longer duration, but also in the cause. Whereas acute rhinosinusitis is caused by a bacterial or viral infection, the etiology of chronic rhinosinusitis has, until now, been less well-defined.

Recent studies by researchers at the Mayo Clinic in Rochester, Minnesota have revealed that the underlying cause for chronic rhinosinusitis may in fact be the presence of fungus in the nasal cavity that causes an immune response in some people that then results in the symptoms of CRS. This ground-breaking research has led to better understanding of the condition and the availability of new treatment options.