Glue ear - Causes of glue ear

The exact cause of glue ear is unknown, but it seems to be caused by a problem with a part of the body called the Eustachian tube.

The Eustachian tube

The Eustachian tube is a thin tube that runs from your middle ear to the back of your throat. It has two main functions:

• to ventilate your middle ear, helping to maintain a normal air pressure within it – sudden changes in air pressure can be painful and can sometimes damage the ears (changes in air pressure are responsible for the popping sensation that many people experience on an aeroplane)
• to help drain away mucus and other debris from the ear – the middle ear can often become clogged with mucus caused by inflammation, infection or an allergic reaction

With glue ear, the Eustachian tube seems to lose the ability to drain away the mucus. The mucus builds up inside the ear, which leads to glue ear. The reasons for this loss of function are still unclear, but some suggestions include:

• changes in air pressure inside the ear that lead to a blockage in the Eustachian tube
• inflammation of the Eustachian tube caused by allergic rhinitis, infection or irritants such as cigarette smoke, which causes the tube to narrow
• gastric fluids from the stomach that leak up through the throat and into the Eustachian tube
• inflammation and swelling of the adenoid glands (small lumps of tissue located at the back of the throat that form part of a child's immune system)

Children are more susceptible to problems like these because the Eustachian tube is smaller and more horizontal during childhood, which means it can't drain as effectively as it can in adults. As the Eustachian tube develops with age, glue ear becomes much less common.

Increased risk

While it is not known exactly what causes glue ear, several things have been identified that may increase the risk of children developing the condition. These include:

• living in a house where the parents smoke
• being bottlefed rather than breastfed
• having a brother or sister who also developed glue ear
• having contact with lots of other children, such as at a nursery (this may be because of a higher risk of infection)
• having a cleft palate, a type of birth defect where a child has a split in the roof of their mouth
• having allergic rhinitis, an allergic condition that causes cold-like symptoms, such as having a runny nose and sneezing
• having Down's syndrome, a genetic disorder that causes learning difficulties and disrupts physical development
• having cystic fibrosis, a genetic condition that causes the lungs to clog up with thick, sticky mucus