Sinusitis is an inflammation of the paranasal sinuses. The full medical term for sinusitis is "rhinosinusitis" ("rhino-" meaning "nose"), because it affects the mucous membranes lining both the nose and the sinuses.
The paranasal sinuses are part of the upper airways, and are connected to the nasal cavity. They are made up of several cavities in the skull found from the forehead down to the teeth of the upper jaw. Depending on where they are, these cavities are known as the frontal sinuses, the sphenoid sinus, the ethmoid cells and the maxillary sinuses. The paranasal sinuses are lined with mucous membranes that have tiny hairs (ciliated epithelium). These mucous membranes produce a secretion that runs down through the nose and throat.
Sinusitis can be acute or chronic: The acute form may appear several times a year, but it always goes away within several weeks at the latest. Chronic sinusitis means that the mucous membranes in the nose are inflamed for a longer period of time. Sinusitis is commonly considered to be chronic if symptoms continue for more than three months.
Sinusitis often has the following typical symptoms:
A build-up of pus
If you have sinusitis, your nose will become stuffed-up due to the swelling and build-up of secretions. This makes it more difficult to breathe through the nose, which feels stuffy. A yellowish or greenish colored discharge is a sign of the presence of germs.
Sinusitis often causes pain in the forehead, the jaw and around the eyes and – less commonly – toothache. The pain usually gets worse if you lean forward, for example when getting up out of bed. Your sense of of smell is often affected, and you may lose it completely. Many people also feel pressure in their face.
Acute sinusitis is often brought on by a cold or the flu. Colds are usually caused by respiratory viruses, and only rarely by bacteria. A bacterial attack, however, may occur in addition to a viral infection.
Viruses or bacteria trigger an inflammation, which causes the mucous membranes to swell up. This may keep fluid from draining from the sinuses. If that happens, the fluid becomes thicker and the sinuses fill up with thick, often yellow-green mucus. Allergies, nasal polyps, a deviated nasal septum (where the wall between the two nostrils is bent to one side) or a weakened immune system can all make sinusitis more likely.
Often it is not known what exactly has caused chronic sinusitis. Sometimes it develops from acute sinusitis that has not cleared up properly. But there are other factors that can make chronic sinusitis more likely or make it worse:
Immune system disorders, for example hay fever or other allergies
Deviated nasal septum (where the wall between the two nostrils is bent to one side) or other abnormalities in or near the nose
Intolerance of acetylsalicylic acid (the drug used in "Aspirin")
Enlarged polyps constrict the nasal cavities, preventing proper ventilation. This makes it easier for germs to grow. Environmental factors like chemicals or cigarette smoke are also thought to play a role.
If acute sinusitis is not completely cured, it can become chronic. One effect of chronic sinusitis can be mucous membrane growths called nasal polyps. They make it more difficult to breathe through your nose and can impair your sense of smell.
In very rare cases sinusitis can lead to complications, with the inflammation spreading to nearby parts of the body like the eyes or brain. Signs of this more serious form of sinusitis include high fever, swelling around the eyes, inflamed and reddened skin, severe facial pain, sensitivity to light and a stiff neck. If you have these symptoms, it is important to seek medical assistance immediately.
Your doctor will first ask about symptoms such as pain, fever, coughing, coughed-up phlegm and loss of smell, and about your general wellbeing and then perform a series of examinations. A tube-like device with a small lamp on it (endoscope) can be used to take a closer look at the inside of your nose and see whether the membranes are swollen and what color the secretions are. In rare cases the secretions are sampled using a probe and examined for germs in a lab. The sample is taken by inserting a probe into the nose. Computed tomography (CT) or ultrasound can be used if a sample is not enough to provide a clear diagnosis or if there are signs of complications.
Finding out whether sinusitis is caused by bacteria or viruses can be quite involved. Often it will not make any difference, because knowing will not influence your symptoms or decisions about treatment. Acute sinusitis usually clears up within one or two weeks.
An allergy test can help in case of chronic sinusitis: Allergies are commonly associated with chronic sinusitis.
Steroidal or decongestant nasal sprays may relieve discomfort in patients with sinusitis. Nasal irrigation or inhalation may also help, and antibiotics may be an option in some cases.
In case of chronic inflammation, one common treatment is surgery to expand narrowed paranasal sinus passageways. This is an option if steroid sprays and other treatments do not provide enough relief.