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Otitis externa
OVERVIEW: Inflammation of the external auditory canal
• Acute diffuse otitis externa - the most common form, an infectious process usually bacterial, occasionally fungal
• Acute circumscribed otitis externa - synonymous with furuncle. Associated with infection of the hair follicle.
• Chronic otitis externa - same as acute diffuse, but of longer duration (greater than 6 weeks)
• Eczematous otitis externa - may accompany typical atopic eczema or other primary skin conditions
• Necrotizing malignant otitis externa - an infection which extends into the deeper tissues adjacent to the canal. May include osteomyelitis and cellulitis. Rare in children.
System(s) affected: Skin/Exocrine
Genetics: N/A
Incidence/Prevalence in USA:
• Unknown; incidence is higher in the summer months
• Acute, chronic and eczematous - common
• Necrotizing - uncommon
Predominant age: All ages
Predominant sex: Male = Female
SIGNS AND SYMPTOMS: • Itching
• Plugging of the ear
• Otalgia
• Periauricular adenitis
• Erythematous canal
• Purulent discharge
• Eczema of pinna
• Cranial nerve involvement (VII, IX-XII)
CAUSES: • Acute diffuse otitis externa
• Traumatized external canal (eg, from use of cotton tip swab)
• Bacterial infection - pseudomonas (67% cases); staphylococcus; streptococcus; gram negative rods
• Fungal infection - aspergillus (90% cases); Phycomycetes; Rhizopus; actinomyces; Penicillium; yeast
• Chronic otitis externa
• Bacterial infection - pseudomonas
• Eczematous otitis externa (associated with primary skin disorder):
• Eczema
• Seborrhea
• Neurodermatitis
• Contact dermatitis
• Purulent otitis media
• Sensitivity to topical medications
• Necrotizing otitis externa
• Invasive bacterial infection - pseudomonas
RISK FACTORS: • Acute and chronic otitis externa
• Traumatization of external canal
• Swimming
• Hot humid weather
• Use of a hearing aid
• Eczematous
• Primary skin disorder
• Necrotizing otitis externa in adults
• Elderly
• Diabetes mellitus
• Debilitating disease
• Necrotizing otitis externa in children (rare)
• Leukopenia
• Malnutrition
• Diabetes mellitus
• Diabetes insipidus
DIAGNOSIS DIFFERENTIAL DIAGNOSIS: • Idiopathic ear pain
• Hearing loss
• Cranial nerve palsy (VII, IX-XII) with necrotizing otitis externa
• Wisdom teeth eruption
• Basal cell or squamous cell carcinoma
LABORATORY: Gram stain and culture of canal discharge (occasionally helpful)
Drugs that may alter lab results: Antibiotic pretreatment
Disorders that may alter lab results: N/A
PATHOLOGICAL FINDINGS: • Acute and chronic otitis externa - desquamation of superficial epithelium of external canal with infection
• Eczematous otitis externa - pathologic findings consistent with primary skin disorder, secondary infection on occasion
• Necrotizing otitis externa - vasculitis, thrombosis and necrosis of involved tissues; osteomyelitis
SPECIAL TESTS: N/A
IMAGING: Radiologic evaluation of deep tissues in necrotizing otitis externa
DIAGNOSTIC PROCEDURES: N/A
TREATMENT APPROPRIATE HEALTH CARE: Outpatient, except for resistant cases and necrotizing otitis externa
GENERAL MEASURES: • Thorough cleansing of external canal
• Narcotic analgesics
• Antipruritic and antihistamines (eczematous form)
• Ear wick (Pope) for nearly occluded ear canal
SURGICAL MEASURES: N/A
ACTIVITY: No restrictions
DIET: No restrictions
PATIENT EDUCATION: • Discuss Prevention/Avoidance
MEDICATIONS DRUG(S) OF CHOICE: • Acute bacterial and chronic otitis externa
• Topical therapy for approximately 10 days
• 2% acetic acid (VoSol HC) fill ear canal qid OR
• Neosporin-polymyxin B - hydrocortisone (Cortisporin); if the tympanic membrane is ruptured use the suspension, otherwise the solution can be used
• Ciprofloxacin (Cipro) 500 mg bid in adults
• Analgesics: hydrocodone-acetaminophen (Vicodin)
• Fungal otitis externa
• Topical therapy anti-yeast for Candida or yeast
• Nystatin
• Clotrimazole applied to the ear canal q3d with cotton-tipped applicator
• Parenteral antifungal therapy - amphotericin B
• Patients with Ramsay Hunt syndrome: acyclovir IV
• Eczematous otitis externa - topical therapy
• Aluminum acetate 8%
• Acetic acid 2% in aluminum acetate
• 5% aluminum acetate (Burrow's) solution
• Steroid cream, lotion, ointment (e.g., triamcinolone 0.1% solution)
• Antibacterial, if superinfected
• Necrotizing otitis externa
• Parenteral antibiotics - antistaphylococcus and antipseudomonal
• 4-6 weeks of therapy
Contraindications:
• Hypersensitivity to topical or parenteral therapy
• Renal or hepatic failure when using amphotericin B
Precautions: Dosage adjustment for amphotericin B in patients with renal or hepatic dysfunction
Significant possible interactions:
• Hypokalemia associated with amphotericin B may lead to digitalis toxicity
• Concurrent administration of nonabsorbable anions, such as carbenicillin, may exacerbate hypokalemia
ALTERNATIVE DRUGS: Azole antifungals for fungal otitis externa
FOLLOW UP PATIENT MONITORING: • Acute otitis externa
• 48 hours after therapy instituted to assess improvement
• At the end of treatment
• Chronic otitis externa
• Every 2-3 weeks for repeated cleansing of canal
• May require alterations in topical medication, including antibiotics and steroids
• Necrotizing otitis externa
• Daily monitoring in hospital for extension of infection
• Baseline auditory and vestibular testing at beginning and end of therapy
PREVENTION/AVOIDANCE: • Avoid prolonged exposure to moisture
• Utilize preventive antiseptics
• Treat predisposing skin conditions
• Eliminate self-inflicted trauma to canal
• Diagnose and treat underlying systemic conditions
POSSIBLE COMPLICATIONS: • Mainly a problem with necrotizing otitis externa. May spread to infect contiguous bone and CNS structures.
• Acute otitis externa may spread to pinna causing a chondritis
EXPECTED COURSE AND PROGNOSIS: • Acute otitis externa - rapid response to therapy with total resolution
• Chronic otitis externa - with repeated cleansing and antibiotic therapy the majority of cases will resolve. Occasionally, surgical intervention is required for resistant cases.
• Eczematous otitis externa - resolution will occur with control of the primary skin condition
• Necrotizing otitis externa - can usually be managed with debridement and prolonged parenteral antibiotics. Recurrence rate is 100% when treatment is inadequate. Surgical intervention may be necessary in resistant cases or if there is cranial nerve involvement. Mortality rate is significant, probably secondary to the underlying disease.
MISCELLANEOUS ASSOCIATED CONDITIONS: See Risk Factors
AGE-RELATED FACTORS: N/A
Pediatric: N/A
Geriatric: N/A
Others: N/A
PREGNANCY: N/A
SYNONYMS: • Swimmer's ear
ICD-9-CM: 380.10 infective otitis externa, unspecified
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