If Sinusitis lasts longer that 3 months, it is chronic. The treatment of chronic sinusitis involves: Longer antibiotic course plus systemic cortisone, Nasal Rinses, and later topical cortisone sprays. If the sinusitis does not resolve a CT scan of the sinuses is done to determine the extent of the Sinus disease and any anatomical factors contributing. Patient may require surgical drainage or Sinus Wash Out, or specific surgery called Functional Endoscopic Sinus Surgery which your doctor will discuss with you in detail. The operation is done under general anaesthetic.