What are the sinuses?

The sinuses are a set of air filled spaces situated in the bones of the face and skull. There are four pairs of sinuses in total. Their precise role is poorly understood, although various theories exist as to their function, such as assisting in the control of temperature and humidity of the air reaching the lungs, modifying the tonal quality of voice production and lightening the weight of the skull.

The sinuses are tiny or in some cases nonexistent at birth. They gradually expand and grow throughout childhood and into young adulthood. Eventually they become air-filled cavities that are lined with exactly the same type of lining as that of the nose. The air gets into the sinuses through tiny openings into the nose.

What do the sinuses do?

When functioning normally, the nose and sinuses produce approximately a pint and a half of mucus secretions per day. This mucus passes through the nose and traps irritant particles breathed in such as dust, pollen, bacteria and other pollutants along the way. The mucus is gently swept towards the back of the nose and throat by millions of tiny hair-like structures called cilia, which line the nasal cavity. The mucus moves into the throat and is swallowed. Most people do not notice this mucus flow because it is an unconscious, normal bodily function which takes place gradually and continuously throughout the day.

Types of sinus infection:

The sinuses can get infected from time to time. Sinus infection occurs in two types:

  • Acute sinusitis gives rise to severe symptoms but is usually short-lived. Acute sinusitis usually occurs following a cold or upper respiratory infection. The patient will typically notice a profuse green-yellow nasal discharge which can last a week or more after the onset of the cold. This is often associated with severe pain around the cheeks, eyes and/or forehead, a blocked nose, as well as an occasional swelling and a high fever.
  • Chronic sinusitis is a form of sinusitis that continues for many weeks, usually in excess of 12 weeks. Chronic sinusitis may be triggered by an acute sinus infection which fails to resolve or as a result of an underlying allergy affecting the lining of the nose and sinuses. As the nose is almost always involved in the problem, the term chronic rhinosinusitis is now used as it more accurately describes the inflammatory and infective process than chronic sinusitis. Common symptoms include nasal obstruction, headache, nasal discharge, low grade fever, reduced sense of smell, facial pain, lethargy and halitosis.

What causes sinusitis?

Acute or chronic rhinosinusitis occurs when the sinus openings into the nose become blocked. These blockages may be caused by infections, irritants, allergies, structural abnormalities or a combination of these. It is worth mentioning that pain in the face may well be due to other causes such as tension headache, migraine, neuralgia and jaw dysfunction. This means that if facial pain is the main symptom, rhinosinusitis is unlikely particularly in the absence of any of the other cardinal symptoms usually associated with this condition.

  • Upper respiratory tract Infections (the common cold or ‘flu):Most adults will get colds and upper respiratory tract infections up to three times a year. Children get them more frequently! The common cold is typically caused by a virus although secondary bacterial infections often follow. When this happens, the mucus changes from clear to yellow or green, indicating that the sinus openings are becoming blocked and more and more inflamed and infected. As the infection takes hold, this further slows down or even stops the normal proper sinus drainage and the infection develops even further.
  • Irritants: This includes air pollution, diesel fumes, smoke, chemical irritants such as sprays containing pesticides, disinfectants and household detergents. If inhaled in sufficient quantities or in susceptible individuals, these irritants may cause swelling and blockage of the lining of the nose causing a narrowing of the drainage opening from the sinuses. This can once again lead to impairment of sinus drainage and subsequent infection.
  • Allergies: The types of allergies that are associated with rhinosinusitis are those that can be inhaled through the nose. The commonest aeroallergens include tree and grass pollen, house dust mite, types of airborne fungi, cat and dog allergens and feathers. If you are allergic to one or more of these allergens, even a tiny quantity inhaled into the nose can cause considerable inflammation of the inner lining of the nose and sinuses. Common symptoms of an allergic reaction include nasal stuffiness, runny nose (which is initially watery and may become thicker later on), sneezing and itchy watery eyes.
  • Structural problems: Occasionally structural problems within the nasal cavity can cause a narrowing, for example if there is a deviation of the nasal septum, excessive swelling of the inner nasal lining or the presence of nasal polyps (see separate information sheet). Some of these can be caused as a result of trauma while others may develop during the growth period. Occasionally the structural narrowing can be so severe that mucus builds up behind these areas of blockage giving rise to sinus infections.

Can my asthma get worse if I have rhino-sinusitis?

Chronic rhinosinusitis is sometimes associated with asthma. Allergies are responsible for asthma in some patients and may also cause nasal stuffiness making the asthma more difficult to control. This is because the nose serves an important function of warming, humidifying and filtering the air that we breathe in, meaning that the lungs receive a high consistent quality of air. If the nose is unable to achieve these improvements in air quality, the lungs receive poorer quality, dry air full of irritants and allergens which make the asthma worse.

Interestingly, if the rhinosinusitis and/or allergy are adequately treated with an intranasal steroid spray, there is good evidence that asthma can improve without the need for any inhaled asthma treatments. This further proves the link between inflammation in the nose and sinuses and the presence of asthma.

Diagnosis and treatment of rhinosinusitis

Acute sinusitis is usually treated with antibiotics and nasal decongestants which reduce the swelling of the nasal lining. This may be assisted by steam inhalations and/or salt water douches to cleanse the nose.

Chronic rhinosinusitis often requires longer term treatment. Medical therapies include antibiotics when required, decongestants and other treatments to reduce the swelling of the inner lining which usually revolve around the use of intranasal steroid sprays or drops. Antihistamines will have a place in patients with an underlying allergy. In the vast majority of cases, chronic rhinosinusitis can be managed effectively with medical treatment.

Occasionally, symptoms will persist despite the ongoing use of medications. In such cases, it may be necessary to consider surgery. If this occurs, your GP will probably refer you to an ENT specialist who will assess your symptoms and examine your nose and sinuses with a nasal endoscope. You may require further investigations including allergy tests and possibly a CT scan of the sinuses, which will help your specialist decide if you need to proceed with surgery.

Sinus surgery

Surgery is normally only considered if medical treatment fails. When surgery is needed, there are a number of different options available depending on the severity of the sinus disease. Nowadays, the vast majority of sinus operations are performed entirely though the nose without the need for any external incisions.

The surgical options include functional endoscopic sinus surgery (FESS), sinus washouts (which are less commonly performed nowadays) and balloon sinuplasty, a non-invasive technique in which the sinus openings are dilated open with a balloon. Please see separate information sheets about these different options.