2.1.1
The paranasal sinuses are small, air-filled cavities, located within the bony structures of the face, which communicate with the nasal space via small openings (ostia). Sinusitis occurs as a result of inflammation of the mucosal lining of the paranasal sinuses. Typical symptoms include fever, pain and tenderness over the infected area, together with a blocked or runny nose. Acute sinusitis frequently resolves spontaneously with little or no treatment. Chronic sinusitis is less common, and symptoms can persist for weeks or months.