Definition of Sinusitis:

Sinusitis refers to inflammation of the sinuses that occurs with a viral, bacterial, or fungal infection.

See also: Chronic sinusitis

Causes, incidence, and risk factors:

The sinuses are air-filled spaces in the skull (behind the forehead, nasal bones, cheeks, and eyes) that are lined with mucus membranes. Healthy sinuses contain no bacteria or other organisms (they are sterile) and are open, allowing mucus to drain and air to circulate.

When inflamed, the sinuses become blocked with mucus and can become infected. Each year, over 30 million adults and children get sinusitis.

Sinusitis can be acute (lasting anywhere from 2 - 8 weeks) or chronic, with symptoms lingering much longer.

Sinusitis can occur from one of these conditions:

• Small hairs (cilia) in the sinuses, which help move mucus out, are not working properly.The small openings (ostia) from the sinuses to the nose become blocked.
• Too much mucus is produced.

When the sinus openings become blocked and mucus accumulates, this becomes a great breeding ground for bacteria and other organisms.

Sinusitis usually follows respiratory infections, such as colds, or an allergic reaction. Some people never get sinusitis, and others develop sinusitis often.

People more likely to get frequent sinusitis include those with cystic fibrosis and those with immune systems weakened by HIV or chemotherapy.

The following may increase your risk for developing sinusitis:

• Air pollution and smoke
• Allergies
• Asthma
• Changes in altitude (flying or scuba diving)
• Dental work
• Deviated nasal septum, nasal bone spur, or polyp
• Foreign body in your nose
• Frequent swimming or diving
• Gastroesophageal reflux disease (GERD)
• Hospitalization, especially if you are in the hospital because of a head injury or have had a tube placed into your nose (nasogastric tube)
• Overuse of nasal decongestants
• Pregnancy

Cystic fibrosis is one of a number of diseases that prevent the cilia from working properly. Other such diseases that put you at increased risk for sinusitis include Kartagener syndrome and immotile cilia syndrome.