Clinical Evidence Concise

A Publication of BMJ Publishing Group

Otitis Externa

Am Fam Physician. 2004 Nov 1;70(9):1741-1742.

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). EB CME is clinical content presented with practice recommendations supported by evidence that has been systematically reviewed by an AAFP-approved source. The evidence is available at http://www.clinicalevidence.com/ceweb/conditions/ent/0510/0510.jsp.

What are the effects of empirical treatment?

LIKELY TO BE BENEFICIAL

Topical Aluminium Acetate Drops (As Effective As Topical Anti-Infective Agents).We found no randomized controlled trials (RCTs) that compared topical aluminium acetate with placebo. One RCT in people with acute diffuse otitis externa found no significant difference between aluminium acetate drops and topical polymyxin–neomycin–hydrocortisone drops in clinical cure rate at four weeks..

Topical Anti-Infective Agents (Antibiotics or Antifungals with or Without Steroids). One RCT found that methylprednisolone–neomycin drops improved symptoms and signs compared with placebo at 28 days. Two RCTs found no significant difference in cure rate between topical quinolones and other topical anti-infective agents. One RCT found that triamcinolone–neomycin drops improved resolution rates compared with hydrocortisone–neomycin–polymyxin B drops. Two RCTs found limited evidence that neomycin–dexamethasone–acetic acid spray improved clinical cure compared with topical anti-infective drops that did not contain acetic acid. We found no RCTs on the effects of topical anti-infective agents versus oral antibiotics..

Topical Steroids. One RCT in people with mild or moderate, acute or chronic otitis externa found that topical budesonide improved symptoms and signs compared with placebo. We found no RCTs of topical steroids compared with topical anti-infective agents. One RCT found no significant difference in symptom scores between low-potency steroid (topical hydrocortisone) and high-potency steroid (topical hydrocortisone butyrate) after one week.

UNKNOWN EFFECTIVENESS

Oral Antibiotics. We found no RCTs of oral antibiotics compared with placebo or topical anti-infective agents.

Specialist Aural Toilet. We found no RCTs that compared specialist aural toilet with no aural toilet. One RCT found no significant difference between an ear wick with anti-infective drops versus ribbon gauze impregnated with anti-infective ointment in resolution rates after four weeks.

UNLIKELY TO BE BENEFICIAL

Oral Antibiotics Plus Topical Anti-Infective Agents (No Better Than Topical Anti-Infective Agents Alone).One RCT found limited evidence of no significant difference between oral co-trimoxazole plus topical anti-infective ointment and topical anti-infective ointment alone in symptom severity, symptom duration, and cure rate.

Definition

Otitis externa is inflammation, often with infection, of the external ear canal. This inflammation usually is generalized throughout the ear canal, so it often is referred to as “diffuse otitis externa.” The present topic excludes localized inflammations such as furuncles. Otitis externa has acute (less than six weeks), chronic (greater than three months), and necrotizing (malignant) forms. Acute otitis externa may present as a single episode, or recur. It causes severe pain with aural discharge and associated hearing loss.1 If the ear canal is visible, it appears red and inflamed. Chronic otitis externa may result in canal stenosis with associated hearing loss, for which it may be difficult to fit hearing aids. Necrotizing otitis externa is defined by destruction of the temporal bone, usually in people with diabetes or in people who are immunocompromised, and it can be life-threatening.2 In this review, we look at empirical treatment of acute and chronic otitis externa only.

Incidence/Prevalence

Otitis externa is common in all parts of the world. The incidence is not known precisely, but 10 percent of people are thought to have been affected at some time.3 The condition affects children but is more common in adults. It accounts for a large proportion of the workload of otolaryngology departments, but milder cases often are managed in primary care.3

Etiology/Risk Factors

Otitis externa may be associated with local or generalized eczema of the ear canal. It is more common in swimmers, in humid environments, in people with an absence of ear wax or narrow external ear canals, in hearing aid users, and after mechanical trauma.4

Prognosis

We found few reliable data. Many cases of otitis externa resolve spontaneously over several weeks or months. Acute episodes have a tendency to recur, although the risk of recurrence is unknown. Experience suggests that chronic inflammation affects a small proportion of people after a single episode of acute otitis externa, and may rarely lead to canal stenosis.1

search date: July 2003

editor’s note: Aluminium acetate drops and neomycin–dexamethasone–acetic acid spray are not available in the United States. Methylprednisolone–neomycin drops are approved by the U.S. Food and Drug Administration, but not marketed in the United States. Co-trimoxazole is called trimethoprim/sulfamethoxazole in the United States.

Adapted with permission from Hajioff D. Otitis externa. Clin Evid Concise 2004;11:677–83.

 

REFERENCES

1. Agius AM, Pickles JM, Burch KL. A prospective study of otitis externa. Clin Otolaryngol. 1992;17:150–4.

2. Doroghazi RM, Nadol JB, Hyslop NE, et al. Invasive external otitis. Report of 21 cases and review of the literature. Am J Med. 1981;71:603–18.

3. Raza SA, Denholm SW, Wong JC. An audit of the management of otitis externa in an ENT casualty clinic. J Laryngol Otol. 1995;109:130–3.

4. Hirsh BE. Infections of the external ear. Am J Otolaryngol. 1992;17:207

This is one in a series of chapters excerpted from Clinical Evidence Concise, published by the BMJ Publishing Group, Tavistock Square, London, United Kingdom. Clinical Evidence Concise is published in print twice a year and is updated monthly online. Each topic is revised every 12 months, and subscribers should view the most up-to-date version at http://www.clinicalevidence.com. If you are interested in contributing to Clinical Evidence, please contact Klara Brunnhuber (kbrunnhuber@bmjgroup.com). This series is part of the AFP’s CME. See “Clinical Quiz” on page 1633.


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