The paranasal sinuses are airfilled cavities located inside the bone of the human skull. While we are not entirely sure of their function, we do know that air pockets within solid structures provide increased strength and reduced weight. The four principal sinuses include the maxillary sinuses (in the cheeks), the frontal sinuses (in the forehead), the anterior and posterior ethmoid sinuses (which are a collection of very small cavities between the eyes), and the sphenoid sinuses (behind the nose and under the brain) . Sinusitis is a condition characterized by inflammation of the mucosal lining of one or more of these sinuses.
Acute sinusitis is a bacterial infection of the paranasal sinuses that follows a typical cold. While colds usually resolve within 5 to 7 days, patients with acute sinusitis usually have symptoms of worsening facial pain and yellow or green nasal discharge. Acute sinusitis is usually diagnosed on clinical grounds, and xrays are generally not needed.
Chronic sinusitis is most often suspected when patients have had some combination of upper airway symptoms including discolored postnasal drip, nasal congestion, facial fullness or headache, cough, and/or sore throat for longer than 3 months.
The pathogenesis of chronic sinusitis is not entirely understood, but there is increasing evidence to support the idea that allergies can predispose a person to persistent sinus inflammation. Allergies do this by causing swelling of the areas where the sinuses drain into the nose, preventing secretions from leaving the sinuses. Very much like allergic rhinitis, nonallergic rhinitis can do the same thing, inducing persistent inflammation of the drainage tracts of the sinuses. Other causes of recurrent sinus infections include structural abnormalities within the nasal passages and sinuses, such as a deviated septum (the structure that divides the nasal passage into two sides) and other bony abnormalities that may prevent the sinuses from draining. These abnormalities are usually found with CT (computed tomography) scans of the sinuses, and they may require surgery.
Many patients have acid reflux, which in severe cases may go all the way up to the throat and nose and result in persistent inflammation. Problems with low immune function, particularly involving the formation of antibodies, can predispose people to various types of infections, including sinusitis. Rarely, cystic fibrosis, which causes a genetic abnormality in mucus thickness, and primary ciliary problems, which result in an inability to clear secretions, may cause chronic sinus problems.
Acute sinusitis
Inflammation of the mucosal lining of the paranasal sinuses lasting more than 10 days and usually associated with bacterial infection. Antibiotics are generally required for resolution of symptoms.
Chronic sinusitis
Inflammation of the mucosal lining of the paranasal sinuses that persists for more than 3 months.