The sinuses are openings in the bones around the nose. There are 4 pairs of sinuses connected to the nasal cavity by small openings. Normally, air passes in and out of the sinuses, and mucus and fluid drain from the sinuses into the nose.

Sinusitis occurs when there is infection, or inflammation due to allergies, in one or more of the sinuses. Acute sinusitis is often associated with upper respiratory infections, as inflammation of the nasal passages prevents drainage of fluid from the sinuses, which allows infection of the sinuses to occur.

A deviated nasal septum or other obstruction of the nose may also trap fluid in a sinus, causing chronic sinusitis. Dental infections such as tooth abscess may spread into the sinus and infect it directly.

Chronic sinusitis is much less common than acute sinusitis. When sinusitis recurs frequently, or lasts for a prolonged period of time, it is classified as chronic. While acute sinusitis is usually caused by infection with a single type of bacteria or virus, chronic sinusitis is usually caused either by allergies or by infection with a mixture of different types of bacteria.

Chronic sinusitis may have less severe symptoms than acute sinusitis but can cause damage and destruction to the tissues of the sinuses. It may flare up spontaneously or may follow respiratory infections such as colds.

Allergy to the aspergillus species of fungus appears to cause a particularly difficult to treat form of chronic sinusitis.

• headache (in the front of the head or around the eyes)
• facial pain around the eyes or in the forehead or cheeks
• pain in the roof of the mouth or teeth
• nasal drainage (yellow, yellow-green, thick)
• cough

• Percussion over a sinus shows tenderness.
• Normal sinuses transilluminate (glow when a light is shone directly on the sinuses), but sinuses do not transilluminate when sinusitis is present.
• Sinus X-rays, cranial CT scan, or cranial MRI shows the sinuses to be filled with fluid, or shows thickening of the membranes of the sinus.
• Aspiration of the sinuses may provide information on the bacteria causing the infection.

The goals of treatment are the cure of the infection and the relief of symptoms.

Antibiotics may be given if the infection is bacterial; treatment is usually prolonged (3-4 weeks). Oral decongestants are sometimes used. Over-the-counter analgesics may be used to control pain.

Topical steroids in the form of a nose spray may be helpful in chronic sinusitis related to allergy. Surgery to clean and drain the sinuses may be necessary. Repair of a deviated septum or nasal obstruction may prevent recurrence of chronic sinusitis.

• recurrence of chronic sinusitis
• spread of infection into the bones of the face (osteomyelitis)
• spread of infection into the brain (meningitis)
• abscess formation, including (rarely) brain abscess