The term sinusitis refers to the presence of inflammation in the paranasal sinuses. This inflammation may be accompanied by concurrent infection, and may affect one or more sinuses on one or both sides. Sinusitis can occur when the drainage and ventilation of the sinuses becomes obstructed, and may be present in one of three (3) forms: acute (less then 12 weeks), chronic (more than 12 weeks) or recurrent. The predisposing factors for sinusitis can be divided into 3 categories: