What -is -Sinusitis -and -What -Causes -it (2)

The sinuses are small hollow pockets situated behind the cheekbones, the bridge of the nose, and just above the eyebrows.

When the lining of these pockets becomes inflamed, this is referred to as rhinosinusitis, or sinusitis for short.

On this page, we’ll discuss the symptoms of sinusitis, what causes it, the link between sinusitis and asthma and allergies, and what treatment involves.

What are the sinuses?

The paranasal sinuses are a series of small cavities, located around our nose:

  • the frontal sinuses are situated behind our forehead, just above our eyebrows
  • the ethmoidal sinuses are located behind the bridge of the nose, between our eyes
  • the sphenoid sinuses are contained within the bone structure behind our nose
  • and the maxillary sinuses are found to the rear of our cheekbones.

These pockets produce mucus, which drains into the nose through small thin tubes.

Why we have sinuses isn’t fully understood, but there are theories. Some think that their biological purpose is to help to heat and humidify the air we inhale, and some think that they help our voices to resonate more.

What is sinusitis?

Sinusitis occurs when the sinuses become inflamed, and this can result in the connecting tubes becoming blocked or congested with mucus.

Someone who has sinusitis may develop:

  • pain in the areas where the sinuses are located (the cheeks, the forehead or around the top of the nose)
  • a blocked nose
  • loss of smell
  • discharge from the nose which is green or yellow
  • a headache
  • toothache
  • high temperature or fever
  • halitosis

The condition can be acute (lasting just a few weeks) or chronic (lasting for more than three months).

What causes acute sinusitis?

Many acute cases occur due to an infection of the upper respiratory tract travelling to the nose and sinuses.

This is typically a viral infection such as the flu, but sometimes sinusitis can be caused by bacterial infections too.

Dental infections can lead to sinusitis but they are a less common cause.

In persons who are immunosuppressed (such as diabetes patients) fungal infections can cause sinusitis as well.

What causes chronic sinusitis?

Chronic cases of sinusitis have been linked to various factors, including:

  • polyps in the nose
  • smoking
  • and a compromised immune system.

Chronic sinusitis may also sometimes be associated with allergic conditions such as hay fever.

When someone develops rhinitis symptoms as a result of an allergic response, this can cause the nasal channels to become blocked. This prevents mucus from the sinuses from being able to drain away freely, and causes infection and/or inflammation in the sinuses.

There is a well established link between chronic sinusitis and asthma. In fact, it is thought that around half of asthmatics whose condition is moderate to severe also have chronic sinusitis.

The cause and effect relationship between sinusitis and asthma runs both ways:

Asthma may cause sinusitis because the airway inflammation which occurs during an asthma flare, in response to an allergen or irritant, affects the sinuses too.

Conversely, a process called postnasal drip (where excess mucus generated in the nasal region runs into the throat and the lower airway), which can occur as a result of sinusitis, is a potential trigger for asthma inflammation and symptoms.

How is sinusitis treated?

It mostly depends on the nature of the condition (whether it is acute or chronic) and the cause.

Acute cases caused by a viral infection will often subside on their own within a couple of weeks. Over the counter medications such as paracetamol can help to reduce headache pain and facial discomfort if necessary, and decongestant nasal sprays can help to clear the airways. These sorts of sprays are used in short courses only (typically for no longer than 5 days).

If symptoms of sinusitis worsen, or do not begin to subside after around a week to 10 days, then its advisable to see a doctor.

If they determine that a bacterial infection is present, they may issue a course of antibiotics to clear it.

In chronic cases of sinusitis, a GP may prescribe a corticosteroid treatment to try and reduce inflammation.

Where the condition occurs as a result of allergic rhinitis, antihistamines can help to treat the root cause, and lessen mucus build-up and sinus inflammation.

Similarly, if asthma flare-ups are contributing to sinusitis, better management of asthma with preventer treatment may help to reduce inflammation and symptoms.

Chronic or recurrent cases of sinusitis that do not respond to the above treatments may need to be referred to an ear, nose and throat specialist (ENT). In some cases, surgery may be required to facilitate better mucosal drainage from the sinuses. The procedure, performed under general anaesthetic, may involve removing any obstructing polyps; or increasing the width of drainage channels with a small catheter.

When should I go to the doctor?

Make an appointment with your GP if you are experiencing persistent sinusitis symptoms, have had symptoms for more than a week to 10 days, or have worsening sinusitis symptoms. Your doctor will be able to determine the cause and discuss appropriate treatment options.