Glue ear

Definition

Glue ear is a complication of a middle ear infection: it is the common name for otitis media with effusion (OME).

This condition arises when the inner (throat) opening of the drainage tube of the ear, the eustachian tube, becomes blocked, due to inflammation or swelling. This prevents the drainage of ear secretions, which then dam up behind the eardrum. Persistent secretions can become thickened with time, hence the name “glue ear”.

Causes

The condition usually arises long after another illness, by which time the child is usually well again.

Otitis media most commonly affects children, and often follows a cold or other upper respiratory tract infection, which involves the inner openings of the eustachian tubes at the back of the throat.

The crucial factor is inadequate drainage. Infection (often mild and unnoticed) of the inner ear produces excess fluid. If this cannot drain away normally, it builds up behind the eardrum. The fluid may itself then become infected, causing complications.

Risk factors 

Factors contributing towards eustachian tube dysfunction include:

• Allergies
• Irritants like cigarette smoke
• Respiratory tract infections
• A sudden increase in air pressure, such as rapid descent in an aeroplane

Children are at greater risk than adults because their eustachian tubes are shorter, straighter and more horizontal. They are also floppier and have smaller openings. All this adds up to a tube which drains less efficiently to start with, is easier for bacteria to access, and is more easily blocked.

Symptoms

Fluid behind the drum causes hearing loss, though small children cannot report this, and it may have to be deduced from their behaviour. Often, the illness resulting in the fluid buildup has passed, so there may be few clues other than the hearing loss. Prolonged effusion in the first few years of life is associated with delayed speech, language and cognitive development.

The child may have disturbed sleep or vertigo: young children cannot describe the sense of turning, but may become clumsy or even fall over.

If there is ongoing acute middle ear infection, the child will be ill with pain and fever.

Diagnosis

Inspecting the eardrum shows a dull membrane, with reduced movement, and occasionally a fluid level or air bubbles can be seen behind the drum.

Special otoscopes can accurately detect fluid in doubtful cases, and a tympanometry test can measure the amount of drum movement.

Hearing loss can also be measured by audiometry.

These tests are needed to select the appropriate treatment.

Treatment

Most cases of OME resolve without treatment, but persistent effusion warrants intervention, to reduce the risk of permanent hearing loss. Remedies considered include:

• Antibiotics - the only medical management shown to have short-term benefit, when used appropriately (therefore of no use in viral infections)
• Decongestants and antihistamines are not useful, and some may make the ear fluid even thicker and more difficult to drain
• Decongestant nasal spray may help to open the inner drainage opening
• Corticosteroids are not recommended
• Autoinflation may be useful, but often cannot be done by a child - it involves forcibly exhaling but with the mouth and nose blocked.

The definitive and most efficient way of draining fluid from the middle ear is by inserting a drainage tube (grommet) into the eardrum. This little rivet-shaped tube will allow fluid out and air in, thereby draining the eustachian tube, and restoring normal hearing. Insertion requires a formal anaesthetic, and is highly successful. There are possible complications - though rare - such as:

• Premature extrusion,
• Persistent perforation, and
• Occlusion of the tubes

Though not routinely recommended, adenoidectomy and/or tonsillectomy may be done at the same procedure if there are clear indications for these procedures in the child.

Outcome

The outcome with appropriate treatment is excellent, but recurrences may occur if underlying trigger and risk factors remain unchanged.

Dr A G Hall