Childhood otitis media i. general practitioner view

Summary
Acute and chronic otitis media are illnesses which remit spontaneously. The short-term benefits of treatment are modest and clinical trials show that no treatment has long-term benefits. It is difficult to recommend any single set of rules for managing otitis media. Management will require choosing from a variety of largely ineffective options according to each patient's needs.

Epidemiology
Acute respiratory infections are responsible for 4.8% of all presentations in Australian general practice. Acute otitis media comprises 1.3% of total general practice presentations and 8% of children's problems.¹ It is the most common reason for febrile children under the age of 4 years to present to the general practitioner. Its annual incidence is about 1 in 100 for adults, and 1 in 10 for children. Children at increased risk include those with abnormal anatomy of the upper respiratory tract e.g. those with cleft palate, the immuno compromised and Aboriginal children living in socio-economically deprived conditions. Otitis media with chronic effusion interferes with the hearing of about 5% of 5 year olds.²

Pathogenesis
The pathogenesis of acute otitis media is probably infective. Infection may ascend into the middle ear cavity from the throat. Pathogenic bacteria are only isolated in the material taken from about half of acutely inflamed middle ear cavities. Viruses are important in the aetiology of many cases.

Natural history
The classical story is of sudden distress, fever and pain in the ear following a minor upper respiratory infection. The pain is poorly localised in young children, so the ear drums should always be examined in a febrile child. Resolution of the pain usually occurs within days (Fig. 1).³ Occasionally, relief is dramatic and accompanied by a discharge of pus from the ear as the drum ruptures. This apparently catastrophic event is benign because the drum usually heals rapidly.

Complications
The acute inflammation often subsides to leave a mild chronic inflammatory process. The thick, sticky fluid left behind in the middle ear cavity dampens the movement of the drum and reduces hearing. Once called 'secretary otitis media', the preferred terms are 'otitis media with effusion' or, more commonly, 'glue ear'. This can be thought of as a delay in the normal recovery from acute otitis media (Fig. 1). It may cause behavioural problems, or, if it occurs at a critical time in language development, educational delay.⁴ Many patients with glue ear have no history of acute otitis media.

In the past, suppurative complications included meningitis, mastoiditis and brain abscess, but these are exceptionally rare now, as is lateral venous sinus thrombosis. The reasons for the fall in incidence of these important complications are unknown, but may be because of the rise in living standards rather than the advent of antibiotics.

Diagnosis
The diagnosis is simple in principle, and based on the otoscopic assessment of the tympanic membrane. In practice it is often difficult. Often, no more than a passing glimpse of the ear drum is achieved. There may be obscuring ear wax.

Even for acute otitis media, there is little agreement on what constitutes a 'properly' inflamed drum: a bulging drum, one which is red, injected, or one in which there is simply loss of the normal light reflex.

Glue ear is even more difficult to diagnose with certainty. Suspected because of recurrent otitis media, unexpected educational delay, or behavioural problems, its otoscopic diagnosis (loss of light reflex, possibly with a fluid level or bubbles visible through the drum) is unreliable. An inflation bulb attached to an air-tight otoscope allows the clinician to deliver a puff of air to the canal. The normal visible medial movement of the drum, which springs back when the pressure is released, is reduced in glue ear. Tympanometry is not readily available to general practitioners, although early reports of the use of suitable hand-held 'microtympanometers' are promising.²

Prophylaxis for acute otitis media
Treating selected upper respiratory infections with antibiotics protects children (particularly) against developing acute otitis media. From pooled results, it is estimated that one case of acute otitis media will be prevented for every 30 cases of sore throat treated with antibiotics. For adults, more than 140 cases would need to be treated with antibiotics to prevent one case of otitis media.⁵

Whatever the evidence for protection against acute otitis media, it does not appear to be important clinically. Initially treating upper respiratory infections liberally with antibiotics results in no fewer return visits for secondary suppurative infections than being parsimonious with them.⁶

Myringotomy
Collections of pus are traditionally managed by the surgical principle of releasing pus by incision. Although myringotomy, the incision of the ear drum, has fallen into disuse in this country (although it is still regarded highly in Scandinavian countries), it has nonetheless been studied in trials. The studies show it has no benefits over any other treatment.⁷

Antibiotics for acute otitis media
Treatment with antibiotics is the usual method of managing acute otitis media in Australia. Benefits for this have been difficult to demonstrate consistently.⁸ Recent double-blind trials show that short-term symptoms (crying, as a measure of pain) may be shortened by about a day. Long-term effects, in particular the resolution of middle ear fluid, are unchanged.³

Most general practitioners accept the modest benefit, and the protection conferred against the rare, serious suppurative complications, and use amoxycillin, which treats streptococcus and haemophilus, particularly for children with the worst symptoms.⁹ Some use amoxycillin with potassium clavulanate when resistance to amoxycillin is suspected, but this precaution is more theoretical than empirical. Antibiotic treatment is not universal e.g. in Holland, most general practitioners do not use antibiotics routinely for otitis media. Australia has one of the highest rates of antibiotic use in the world.¹⁰ Are our patients demonstrably better off as a result?

There is no apparent benefit in reviewing all children with acute otitis media after about two weeks to check for glue ear. Indeed, less than 25% of cases managed in Australia have follow-up visits.¹

Symptomatic management of acute otitis media
Lessons learned from well-designed studies indicate that paracetamol is effective in reducing fever and that warm sponging in addition reduces the fever more quickly.¹¹ However, decongestants and antihistamines have not been shown to confer benefit, despite being used frequently.

Treating glue ear
The indications for treatment are significant chronic bilateral auditory impairment, drum retraction and recurrent bacterial super infection. Adenoidectomy was once performed commonly for glue ear, but as there is no evidence of any benefit, it has become much less popular. Grommet operations (tympanostomy tube insertion after myringotomy) have largely replaced adenoidectomy. There is an immediate improvement of the hearing postoperatively. However, normal hearing usually returns within months without surgery⁴ and there is no long-term difference in the hearing of patients who have had grommet operations compared with those who have not.¹² Perhaps we should be more cautious in the use of grommets⁴, even restricting their use to one ear. Alternatives, such as the use of long-term antibiotics and systemic steroids, have been disappointing.

Conclusion
With little evidence of benefits for any treatment of otitis media, the clinician must exercise considerable expertise in offering the best advice. Investigating the needs of the patient is paramount: some children with acute otitis media may benefit from antibiotics, particularly those crying due to their illness. Other families may be happy to dispense with the expense and risk of adverse reactions to antibiotics.

Some children suffering a temporary loss of normal hearing due to glue ear may benefit more from specific behavioural or educational interventions if schooling or language development are of concern, rather than an operation for grommets requiring a general anaesthetic.