Sinusitis
(Sinus Infection)
In this condition factsheet:
The Facts on Sinusitis
Sinus Infection
The Facts (1, 7-9)
The sinuses are hollow spaces in the bones behind the face. Directly behind the nose is the nasal cavity. On either side of the nasal cavity are large sinuses. A row of very small sinuses runs behind the bridge of the nose, and two more large sinuses are located above and behind the inner part of the eyebrows.
Sinusitis is inflammation of the sinuses. It may be associated with both bacterial and viral infections, but it may be due to non-infectious inflammation (e.g., allergies) in the sinuses as well. Sinusitis can be acute, lasting less than 4 weeks, or chronic, lasting 12 weeks or more. Acute sinusitis is very common, affecting about 1 in 8 people each year.
People with asthma, cystic fibrosis, and allergies are more likely to get sinusitis, as are those who have had their nose broken previously and those who were born with a malformed septum (the dividing wall between the nostrils). People with diabetes or those who are immunocompromised are at increased risk for complications of sinusitis.
Causes of Sinusitis
The sinuses produce mucus that helps to clean the nose and to smell. It's moved out of the sinuses and into the nasal cavity by thousands of tiny hairs, called cilia, which operate in unison to form a sort of conveyor belt. Foreign particles and organisms entering the sinuses land in the mucus and are sent back to the nose. To get to the nose, the mucus has to pass through small holes in the bones that surround the sinuses.
Sinusitis usually begins during a bout of the common cold, influenza (flu), or some other viral infection. This causes the nasal mucous membrane (which is soft tissue inside the nose, not simply mucus) to swell. It can press against the hole through which mucus leaves a sinus.
Most cases of sinusitis are caused by viral infections. However, in a few people, a bacterial infection can develop. This is because when the sinus fills with mucus and empties of oxygen, it creates an ideal setting for bacteria to grow. The bacteria are often already in the nose, but don't cause an infection because they are held in check by the body's natural defences.
If the body's defences (e.g., the cilia, sinus drainage, or immune system) are not working properly, the bacteria can cause an infection. In rare cases, sinusitis can be caused by a fungal infection. People who get fungal sinus infections usually have other medical problems that affect their ability to fight infection (e.g., HIV, cystic fibrosis).
Other things that inflame the nose can also cause sinusitis. For example, hay fever and other allergies increase your chances of getting sinusitis.
Symptoms and Complications of Sinusitis
Sinusitis has symptoms very different from a cold or the flu. The main symptoms are face pain, pressure, and fullness, congestion, nasal discharge and a headache. The location of the pain depends on which sinus or sinuses are affected. Other symptoms include headache, bad breath, fatigue, and cough (especially at night).
Infection of the lower (maxillary) sinuses causes toothache in the upper jaw and pain in the area under the eyes, while infection of the upper (frontal) sinuses causes pain in the temple. Infection of the small sinuses between the eyes (the ethmoid sinuses) causes pain between and behind the eyes. Infection of the sphenoid sinuses (located behind the ethmoid sinuses) causes pain that may be felt in the front or back of the head.
Yellow or green pus may drain out of the nose, and there may be an unpleasant smell. Someone with sinusitis may feel generally unwell and while not common, can also have a low-grade fever (less than 38°C).
A viral infection is different from bacterial sinusitis in that it generally resolves in less than 10 days. If symptoms persist for more than 10 days, the infection is likely bacterial in nature. Sometimes, a biphasic pattern is seen in a bacterial sinusitis, where signs and symptoms start to improve, but get worse again 5 to 6 days later.
Acute sinusitis is usually resolved in less than 30 days. In a few people, however, the infection can last longer. People who have more than 4 episodes per year are considered to have recurrent acute sinusitis and should be referred to a specialist. When symptoms last more than 12 weeks, the condition is called chronic sinusitis.
Serious complications of sinusitis can sometimes occur, including abscesses and meningitis (infection of the membranes surrounding the central nervous system). However, complications such as these are rare.
