Chronic rhinosinusitis (CRS) is a chronic inflammatory disorder affecting nasal passages and paranasal sinus cavities. It is one of the most common chronic respiratory diseases with a significant impact on quality of life and costs of health care. Paranasal sinuses are cavities in the facial and skull bones which communicate with nasal passages on the same side through small openings called sinus ostia. This communication is crucial for regular functioning of the sinus ventilation and drainage. If the communication is blocked by inflammatory process in nasal or sinus cavities or on the both sides of ostia, symptoms of rhinosinuitis occur. Classification of rhinosinusitis, according to the European Position Paper on Rhinosinusitis and Nasal Polyps (EP3OS), developed by a Task Force of the European Academy of Allergology and Clinical Immunology (EAACI), divide rhinosinusitis into acute and chronic, based on the duration of symptoms. Acute rhinosinusitis usually starts as a viral disease, lasting for 7 to 10 days, which may progress due to bacterial superinfection into bacterial rhinosinusitis. In acute rhinosinusitis symptoms last up to 12 weeks.
Chronic rhinosinusitis is defined as the presence of 2 or more symptoms of which 1 should be either nasal blockage or nasal discharge combined with facial pain and/or reduction of smell for more than 12 weeks and the diagnosis should be confirmed with nasal endoscopic signs or corresponding mucosal changes on computerized tomography (CT) scan. Besides nasal blockage, coloured discharge (yellowish, brown) that can be blown through the nose, or drips back from the nose to the throat, facial pain or pressure, headache, and smell loss or reduction, other, less frequent symptoms may occur, like cough, foul odour from the mouth, fatigue, pressure in the ears and fever. Patients with chronic rhinosinusitis have significant reduction in their quality-of-life, which is improved after adequate treatment.
The reason why chronic rhinosinusitis develops is not clear. It may result from previously poorly treated acute bacterial rhinosinusitis, but it seems rarely to be the true cause. It was shown in a number of studies that infection, the most common cause of acute rhinosinusitis, is not the main factor in the development of chronic rhinosinusitis. Even when growth of microorganisms, like bacteria or fungi, was found in nasal and sinus secretions, it was rarely shown that colonizing bacteria or fungi were the cause of the disease. There are many predisposing factors to develop chronic rhinosinusitis, like: distorted anatomy of nasal cavity or sinuses, inadequate immune response to infection, allergy or intolerance to certain drugs, impaired function of the clearance of secretion in nasal and sinus cavities, or scarring from repetitive sinus operations, etc.