Sinusitis is described as the inflammation of the paranasal sinuses (air-filled cavities inside the bones of the skull). Sinusitis may be acute or chronic, and infectious or non-infectious. Anything interfering with airflow into and drainage of mucus out of the sinuses can cause sinusitis. Symptoms include headache, nasal stuffiness, facial tenderness, sore throat, cough, worsening of allergies and purulent nasal discharge. Although rare, sinus infections can cause serious complications, including spread of infection and exacerbation of respiratory tract conditions.
What is the occurance of sinusitis?
Sinusitis is a common condition, affecting approximately 30% of the population at some point. Sinusitis can occur in infants and children, but is more common in adults as sinuses are undeveloped in infants and start forming during childhood. The average adult has 3-4 upper respiratory infections each year, about 1% of which are complicated by sinusitis. In addition to sinusitis associated with viral respiratory infections, many more people suffer inflammation of the sinuses because of seasonal allergic problems.
Types of sinusitis
Sinusitis may be classified based on time span of the problem (acute, sub-acute or chronic), and the type of inflammation (infectious or non-infectious).
- “Sinus headache” – typically lasts a few hours until the ostia unblock and allow equalisation of air pressure in the sinus.
- Acute sinusitis – typically lasts up to a month.
- Sub-acute sinusitis – lasts longer than one month, but less than three months' duration.
- Chronic sinusitis – longer than three months' duration.
- Infectious sinusitis – usually caused by bacterial growth.
- Non-infectious sinusitis – caused by irritants and allergic conditions.
- Acute sinusitis is commonly secondary to either allergic rhinitis (hay fever) or viral infection of the nasal passages. Sub-acute and chronic forms of sinusitis usually result from incomplete treatment of acute sinusitis.
The most common complaint is that of a “sinus headache”. This occurs typically occurs as a result of nasal congestion or sinus mucus which obstructs the ostea leading to a blockage of air flow and equalisation of air pressure in the sinus and the environment. The air in the sinus is absorbed which causes a negative pressure in the sinus, leading to symptoms of a “sinus headache”.
Once the obstruction is relieved, the pressure equalises and the sinus headache improves immediately. The second most common cause for sinus symptoms is when the sinus starts producing mucus in response to irritation or constant blockage. At this stage an antibiotic is not usually required. Infection of the sinus usually is accompanied by a temperature, which may suggest that an antibiotic is required.
What causes sinusitis?
- Anything interfering with airflow into and drainage of mucus out of the sinuses can cause sinusitis.
- The sinus openings may be obstructed by anything, causing swelling of tissue lining the ostia and adjacent nasal passage, such as colds, allergies and tissue irritants (such as over-the-counter nasal sprays, cigarette smoke and recreational substances snorted through the nose).
- Allergies may complicate sinusitis.
- Drainage of mucus can be impaired by thickening of secretions, decrease in mucus hydration (water content) because of disease, drying medications (antihistamines), and lack of air humidity.
- Irritants, especially smoke, may damage cilia, and prevent them from assisting with mucus drainage. Stagnated mucus provides an ideal environment for bacteria and in some cases (such as AIDS) fungus to grow.
- Other irritants include car exhaust, petrol and paint fumes, perfume, insect spray and household chemicals.
- Sinuses can become obstructed by tumours or growths. Nasal polyps (growths arising from mucous surfaces), probably caused by nasal inflammation, can block the ostia.
- Occasionally, immune problems cause sinus infections. If you have persistent sinus infections, have your immune system evaluated by an allergist/immunologist, especially before surgery is done. You may need allergy tests, and tests to ensure you can form antibodies to common bacteria normally. Sinusitis can be due to AIDS, although only an extremely small percentage of people with sinusitis have AIDS.