Sinusitis is inflammation of the sinuses, most commonly caused by an allergy or infection.

Locating the Sinuses The sinuses are hollow cavities in the bones around the nose. The two frontal sinuses are located just above the eyebrows; the two maxillary sinuses, in the cheekbones; and the two groups of ethmoid sinuses, on either side of the nasal cavity. The two sphenoid sinuses (not shown) are located behind the ethmoid sinuses.

Sinusitis is one of the most common medical conditions. About 10 to 15 million people each year develop symptoms of sinusitis. Sinusitis may occur in any of the four groups of sinuses: maxillary, ethmoid, frontal, or sphenoid. Sinusitis nearly always occurs in conjunction with inflammation of the nasal passages (rhinitis), and some doctors refer to the disorder as rhinosinusitis. It may be acute (short-lived) or chronic (long-standing).

Acute Sinusitis: Acute sinusitis may be caused by a variety of bacteria and often develops after something blocks the openings to the sinuses. Such blockage commonly results from a viral infection of the upper airways, such as the common cold. During a cold, the swollen mucous membranes of the nasal cavity tend to block the openings of the sinuses. Air in the sinuses is absorbed into the bloodstream, and the pressure inside the sinuses decreases, causing pain and drawing fluid into the sinuses. This fluid is a breeding ground for bacteria. White blood cells and more fluid enter the sinuses to fight the bacteria; this influx increases the pressure and causes more pain.

Allergies also cause mucous membrane swelling, which blocks the openings to the sinuses. Additionally, people with a deviated septum are more prone to obstructed sinuses.

Chronic Sinusitis: Sinusitis is defined as chronic if it has been ongoing for more than 8 to 12 weeks. Doctors do not understand exactly what causes chronic sinusitis but it may follow a viral infection, a severe allergy, or exposure to an environmental pollutant. Often the person has a family history; a genetic predisposition appears to be a factor. If the person has a bacterial or fungal infection, the inflammation is much worse. Occasionally, chronic sinusitis of the maxillary sinus results when an upper tooth abscess spreads into the sinus above.

Symptoms and Diagnosis

Acute sinusitis usually results in pain, tenderness, and swelling over the affected sinus. Maxillary sinusitis produces pain over the cheeks just below the eyes, toothache, and headache. Frontal sinusitis produces headache over the forehead. Ethmoid sinusitis produces pain behind and between the eyes and headache, often described as splitting, over the forehead. The pain produced by sphenoid sinusitis does not occur in well-defined areas and may be felt in the front or back of the head.

In acute sinusitis, yellow or green pus may be discharged from the nose. Fever and chills also can occur, but their presence may suggest that the infection has spread beyond the sinuses. Any change in vision or swelling around the eye is a very serious condition that can quickly—within minutes to hours—result in blindness. Such a change should be evaluated by a doctor as soon as possible.

The symptoms of chronic sinusitis are usually much more subtle, and pain occurs less often. The most common symptoms of chronic sinusitis are nasal obstruction, nasal congestion, and post-nasal drip. People with sinusitis may have colored discharge and a decreased sense of smell. A person also may feel generally ill (malaise).

A doctor makes the diagnosis based on the typical symptoms and, sometimes, on x-ray studies. X-rays may show fluid in the sinuses, but computed tomography (CT) is better able to determine the extent and severity of sinusitis. If a person has maxillary sinusitis, the teeth may be x-rayed to check for tooth abscesses. Sometimes a doctor passes a thin viewing scope (endoscope) into the nose to inspect the sinus openings and to obtain samples of fluid for culture. This procedure, which requires a local anesthetic, can be done in the doctor's office.

Treatment

Treatment of acute sinusitis is aimed at improving sinus drainage and curing the infection. Nasal sprays, such as phenylephrine, which cause blood vessels to narrow (constrict), can be used for a limited time. Similar drugs, such as pseudoephedrine, taken by mouth are not as effective. For both acute and chronic sinusitis, antibiotics such as amoxicillin or trimethoprim-sulfamethoxazole are given, but people who have chronic sinusitis take antibiotics for a longer period of time. Nasal corticosteroid sprays and corticosteroid tablets are helpful in reducing the inflammation in the mucous membranes. If significant allergy symptoms are present, antihistamines may be useful. Nasal irrigations with salt water can help to cleanse the sinuses and keep them moist. When antibiotics are not effective, surgery may be performed either to wash out the sinus and obtain material for culture or to improve sinus drainage, which allows the inflammation to resolve.

Fungal Sinus Infections A variety of fungi that are normally found throughout the environment can be present in the nose and sinuses of most healthy people. In certain situations, however, fungi can cause significant nasal and sinus inflammation. Fungus balls are an overgrowth of fungi in otherwise healthy people. Symptoms include sinus pain, pressure, nasal congestion, drainage of fluids, and chronic infections. Surgery is needed to open the affected sinus and remove the fungal debris. Allergic fungal sinusitis is a disorder in which fungi cause a reaction characterized by marked nasal congestion and the formation of nasal and sinus polyps. The polyps obstruct the nose and the openings to the sinuses and produce chronic inflammation. The polyps and inflammation often involve only one side of the nose. Surgery is typically required to open up the sinuses and to remove the fungal debris. Long-term treatment is also required with corticosteroids, antibiotics, and sometimes, antifungal drugs applied directly to the area or taken by mouth. These drugs reduce the inflammation and eliminate the fungus. However, even after prolonged treatment, the disorder is very likely to recur. Invasive fungal sinusitis is a very serious disorder that develops most often in people whose immune system is impaired by chemotherapy or by diseases such as poorly controlled diabetes, leukemia, lymphoma, multiple myeloma, or AIDS. It may spread rapidly. Symptoms include pain, fever, and discharge of pus from the nose. The fungus may spread to the eye socket, causing a bulging of the affected eye (proptosis) and blindness. A doctor makes the diagnosis by biopsy. Treatment is with surgery and antifungal drugs given intravenously. Doctors also must control the underlying disease and stimulate a weakened immune system.

Last full review/revision February 2003