What is Sinusitis?

Sinusitis is an inflammation of the sinus membranes that can be infectious (caused by a virus or bacteria) or non-infectious (often caused by allergies). Sinusitis may either be acute or chronic.

Acute bacterial sinusitis is an infection of the sinuses caused by bacteria. It is usually preceded by a cold, allergy attack, or irritation by environmental pollutants. Acute sinusitis, the more prevalent form, is usually caused by a viral cold. Computer tomography (CT) scans reveal that more than 80% of viral colds cause sinus inflammation. Typically, this inflammation – like the cold itself – resolves within two weeks.

However, about 2% of colds in adults and about 20% in children are complicated by a secondary bacterial infection. Most healthy people harbor bacteria like Streptococcus pneumoniae and Haemophilus influenzae in their upper respiratory tracts. These bacteria are kept in check until the body's defenses are weakened or cold blocks drainage from the sinuses. When this happens, the normally harmless bacteria can become trapped by nasal swelling and narrow sinus outflow passages. The trapped bacteria suddenly begin to multiply, causing acute bacterial sinusitis.

In most cases, antibiotics are prescribed for patients with specific persistent purulent nasal discharge and facial pain or tenderness who are not improving after seven days.

Chronic sinusitis is defined as sinusitis that persists for at least 12 weeks. Occasionally, chronic sinusitis develops because of sinus blockage. The condition affects an estimated 32 million Americans and has become a multi-million-dollar industry for pharmaceutical companies that market symptom-relieving sinus medications.

Sinusitis occurs most often in the maxillary sinus area. Symptoms include facial pain, which is sometimes aggravated when stooping. There may also be purulent nasal discharge or altered facial sensations. Headache can be associated with sinusitis. Complications are rare.

Sinusitis involving the frontal sinus regions will present symptoms which may include pain and tenderness over the frontal sinus, fever and purulent discharge. Sometimes the maxillary sinuses become involved as well. Complications may include life-threatening infections such as cranial osteomyelitis or brain abscess; however, these complications are very rare.

Sinusitis in the ethmoid sinus area may lead to complications of the eye such as edema or cellulites of the eyelid and orbital cellulitis. Sinusitis in the ethmoid sinuses may lead to meningitis.

Sphenoid sinusitis is somewhat rare; however, the relationship of the sphenoid sinus to other organs may lead to severe complications such as pituitary insufficiency; or meningitis.

Your very breathing is dependent on clear sinuses, making sinusitis particularly unpleasant.
Sinusitis is usually caused by bacteria, especially S.pneumoniae, H. influenzae and M. catarrhalis. Your doctor may take a culture to determine which bacteria is present, so he or she can figure out how to fight your infection. When the sinuses are blocked, the result is a good environment for infectious bacteria to live. Healthy sinuses have cilia that move bacteria out of the sinus fast enough that bacterial growth cannot occur. However, if the cilia don't beat in their normal harmony due to a bad cold or flu, or if the sinus drainage is blocked, infection may result.