What Is Sinusitis?

Sinusitis is an inflammation of the sinuses, usually caused by a bacterial infection. It's considered acute if it's short-lived and chronic if it's long-lasting -- longer than three months, according to most doctors. Chronic sinusitis is sometimes also defined as four or more occurrences of acute sinusitis in a year. Chronic sinusitis presents the same kinds of symptoms as acute sinusitis though they may not be as severe.

Acute sinusitis is often preceded by a cold, flu, or allergy attack, which inflames the sinus membranes and blocks the sinuses' drainage openings (ostia). Mucus collects, providing a breeding ground for bacteria.

Chronic sinusitis is often preceded by too many cases of acute sinusitis, which cause the ostia to swell shut permanently and bacteria to grow continuously. Chronic sinusitis may also accompany other structural changes in the sinuses, including thickened and stagnant mucus, a paralysis of the tiny hairs (cilia) that are designed to sweep mucus, bacteria, allergens, and other foreign matter out of the sinuses, nasal polyps (growths), and swollen nasal turbinates (areas inside the nose that warm and moisten inhaled air). Sometimes chronic sinusitis may not involve an infection at all but chronic inflammation, a blockage of the ostia, a buildup of mucus, and sinus pressure and pain. In a small percentage of chronic sinusitis cases, the cause is immunological deficiency, as determined by a blood test.

Sinusitis is more common than many other better-known health problems, such as hypertension and arthritis. It affects 15 percent of people each year, according to the American Academy of Otolaryngology. Some experts believe that sinusitis is increasing in frequency as a result of air pollution and exposure to colds and flu from daycare centers. Other experts feel that sinusitis is only apparently increasing in frequency as a result of better diagnostic techniques. And some experts feel that sinusitis is overdiagnosed, that only about half of patients who see doctors for symptoms of sinusitis actually have the condition. According to one statistic, more than 85 percent of people with colds have inflamed sinuses, though unlike with true sinusitis, symptoms are typically brief and mild. Between 0.5 and 5 percent of people with colds develop true sinusitis.

Diagnosis

The symptoms of sinusitis are often similar to those of colds or allergies, which can make diagnosis tricky. Sinusitis, however, is more often accompanied by facial pressure or pain, particularly when bending over, thick yellow or green mucus rather than clear or whitish mucus, and post-nasal drip, particularly at night, leading to a sore throat. Also, acute sinusitis typically lasts longer than the 7 to 10 days of a common cold.

Yellow mucus is a possible indicator of a bacterial sinus infection but not a definitive one. Mucus can turn yellow as a result of sinus inflammation without infection or as a result of mucus drying out.

Doctors also look for swelling, tenderness, and redness of the skin over the cheekbones (these symptoms are usually worse in the morning). They may use transillumination by shining a bright light in a darkened room against the cheek or forehead, looking for blockages. They may look at the sinuses directly with a flexible tube inserted into the nose called an endoscope.

For chronic sinusitis doctors often order a CT scan (computerized tomography, sometimes written as CAT scan and pronounced "cat scan"), which is a specialized X-ray technique. CT scans are more accurate in diagnosing sinusitis than conventional X-rays (plain film radiography) or MRI (magnetic resonance imaging), but reports indicate that they still have a false negative rate of 5 to 10 percent, meaning they don't identify sinusitis in a small percentage of cases.

Some patients have reported that neither an endoscope nor a CT scan identified their sinusitis as the infection was in the bone and required nuclear bone imaging, also called a bone scan, for a proper diagnosis.

It's important that sinusitis be diagnosed and treated because, if not treated, it often just gets worse. Acute sinusitis should be treated no later than two to three weeks after symptoms appear. If not treated acute sinusitis can structurally damage the sinuses and turn into chronic sinusitis, which is more difficult to treat and may require surgery.

Sinusitis can clear up on its own (60 to 70 percent of patients recover from acute sinusitis without need for an antibiotic, according to the American Academy of Allergy, Asthma and Immunology), but in rare cases untreated sinusitis can lead to other more serious health conditions involving the eyes, the bones of the face, and the brain, including osteomyelitis and meningitis.