Diagnosing the discharging ear

A range of features help differentiate the causes of ear discharges, says Dr Julian Spinks

Discharge from the ears (otorrhoea) is common in primary care, and is caused either by diseases of the external auditory canal, such as otitis externa, or by middle ear disease, including otitis media.

Typically, middle ear disease is more common in childhood, and external canal disease is more likely in adulthood.

Trauma or surgery may cause cerebrospinal fluid to leak from the ear and rarely fluid may originate from a parotid fistula.

History

Fever is indicative of an acute infection such as otitis media or externa. Chronic discharge
is more likely in conditions such as chronic suppurative otitis media.

Pain in otitis media is typically crescendo in nature, followed by relief at the onset of otorrhoea.

By contrast, the pain in otitis externa is not relieved by the onset of otorrhoea and begins with itching followed by pain that worsens if the pinna or jaw is moved.

In malignant otitis externa the pain is out of all proportion to the physical signs.

The colour and odour of the discharge also offer clues. A serous or serosanguinous discharge that has no smell and thickens over time is typical of otitis media.

In otitis externa, however, the discharge is scant with a white or clear colour.

A bloody discharge may be the result of tympanic trauma from cotton buds, but can also occur with chronic granulation from infection and tumours. Clear mucoid discharge suggests chronic perforation or discharge from a grommet.

Foul-smelling discharge is associated with cholesteatoma and mastoiditis.

Hearing loss tends to occur earlier in the history with middle ear conditions, but later in external canal disease.

A history of previous middle ear surgery increases the possibility of chronic otitis media or discharge through a tympanostomy tube.

Some skin complaints including eczema are associated with otitis externa.

The patient should be questioned about direct tympanic trauma through use of cotton buds, fingernails or hair clips, which can cause otorrhoea and may also lead to the development otitis externa.

Exposure to dust or immersion in water also predispose to otitis externa.

Examination

A general examination should identify constitutional signs of acute infection. The head and neck should be examined for lymphadenopathy.

In otitis externa a post-auricular gland may push the pinna forwards. This can occlude the canal, and can be mistaken for the mastoid swelling and tenderness of mastoiditis.

Palpation and movement of the pinna that causes pain suggests otitis externa.

In more severe otitis externa, erythema, cellulitis and skin excoriation can move outwards on to the pinna.

An otoscopic examination of the ear canal and tympanic membrane is mandatory, and in otitis externa, it may reveal an oedematous and wet ear canal but a normal drum.

In acute otitis media, the canal should look normal apart from the discharge, but the drum will be red and a perforation will be present.

The drum may also reveal the presence of a tympanostomy tube: 10 per cent of children get otorrhoea after grommet insertion.

Cholesteatoma is an abnormal collection of keratin seen as a white substance in a retraction pocket on the drum, and it is a marker of chronic otitis media.

Not all patients with chronic otitis media develop cholesteatoma, however.

Caution should be exercised if debris or wax obscures the drum. Where this happens, syringeing may be required before any further management on the ear.

In otitis externa and chronic otorrhoea a swab should be sent for culture, including mycology, as 10 per cent of infections are fungal.

Treatment

Antibiotics provide a relatively modest reduction in pain, and duration of discharge, but double the risk of vomiting, diarrhoea and rashes. 

Otitis externa is best treated topically with antibacterials with or without ste- roids. There is limited evidence that aluminium acetate drops may be as effective as antibacterials.

Some ENT specialists use topical aminoglycosides in the presence of a perforation, but this is contraindicated due to the risk of ototoxicity. Oral antibiotics are rarely effective in otitis externa unless there is cellulitis of the pinna.

Referral is advisable for patients with chronic otitis media or mastoiditis, or if there is treatment failure.

Older patients, particularly if they have diabetes, are prone to malignant otitis externa. This causes rapid deterioration leading to skull-base osteomyelitis, which requires emergency hospital admission.

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