Respiratory Conditions / Sinusitis

Viruses can enter the body through the nasal passages and set off a chain reaction resulting in sinusitis. For example, the nose reacts to an invasion by viruses that cause infections such as the common cold, flu, or measles by producing mucus and sending white blood cells to the lining of the nose, which congest and swell the nasal passages. When this swelling involves the adjacent mucous membranes of the sinuses, air and mucus are trapped behind the narrowed openings of the sinuses. If the sinus openings become too narrow to permit drainage of the mucus, then bacteria, which normally are present in the respiratory tract, begin to multiply. Most apparently healthy people harbor bacteria, such as Streptococcus pneumoniae and Haemophilus influenzae, in their upper respiratory tracts with no ill effects until the body's defenses are weakened or drainage from the sinuses is blocked by a cold or other viral infection. The bacteria that may have been living harmlessly in the nose, throat, or sinus area can multiply and cause an acute sinus infection.

Medicines, too, can set off a nasal reaction with accompanying sinusitis. For example, intolerance to aspirin and other related non-steroidal anti-inflammatory medications, such as ibuprofen, can be associated with sinusitis in patients with asthma or nasal polyps (small growths on the mucous membrane lining of the sinuses).

Sometimes, fungal infections can cause acute sinusitis. Although these organisms are abundant in the environment, they usually are harmless to healthy people, indicating that the human body has a natural resistance to them. Fungi, such as Aspergillus and Curvularia, can cause serious illness, in people whose immune systems are not functioning properly. The thymus gland, adrenal glands and the spleen are almost always involved. Some people with fungal sinusitis have an allergic-type reaction to the fungi.

Chronic inflammation of the nasal passages (rhinitis) also can lead to sinusitis. Allergic rhinitis or hay fever (discussed below) is the most common cause of chronic sinusitis and is a frequent cause of acute sinusitis. Vasomotor rhinitis, caused by humidity, cold air, alcohol, perfumes, and other environmental conditions, also can result in a sinus infection.

Chronic Sinusitis

Chronic sinusitis refers to inflammation of the sinuses that continues for weeks, months, or even years.

As noted above, allergies are the most common cause of chronic sinusitis. Inhalation of airborne allergens (foreign substances that provoke an allergic reaction), such as dust, mold, and pollen, often set off allergic reactions (allergic rhinitis) that, in turn, may contribute to sinusitis. People who are allergic to fungi can develop a condition called "allergic fungal sinusitis." As body cells react against these inhaled substances, they release chemical compounds, such as histamine, at the mucosal surface. These chemicals then cause the nasal passages to swell and block drainage from the sinuses, resulting in sinusitis.

Damp weather, especially in northern temperate climates, or pollutants in the air and in buildings also can affect people subject to chronic sinusitis.

Chronic sinusitis can be caused by structural abnormalities of the nose, such as a deviated septum (the bony partition separating the two nasal passages), or by small growths called nasal polyps, both of which can trap mucus in the sinuses.

Sinusitis has its own localized pain signals, depending upon the particular sinus affected. Headache upon awakening in the morning is characteristic of sinus involvement. Pain when the forehead over the frontal sinuses is touched may indicate inflammation of the frontal sinuses. Infection in the maxillary sinuses can cause the upper jaw and teeth to ache and the cheeks to become tender to the touch. Since the ethmoid sinuses are near the tear ducts in the corner of the eyes, inflammation of these cavities often causes swelling of the eyelids and tissues around the eyes and pain between the eyes. Ethmoid inflammation also can cause tenderness when the sides of the nose are touched, a loss of smell, and a stuffy nose. Although the sphenoid sinuses are less frequently affected, infection in this area can cause earaches, neck pain, and deep aching at the top of the head.

Other symptoms of sinusitis can include fever, weakness, tiredness, a cough that may be more severe at night, and runny nose or nasal congestion. In addition, drainage of mucus from the sphenoids down the back of the throat (postnasal drip) can cause a sore throat and can irritate the membranes lining the larynx (upper windpipe).