What are the characteristics, causes, and treatments of inflammatory and non-inflammatory diseases of the external ear?

Inflammatory and Non-Inflammatory Diseases of the External Ear

Inflammatory Diseases of the External Ear

Acute Otitis Externa (Swimmer's Ear)

Acute otitis externa is a bacterial cellulitis of the ear canal requiring topical antimicrobial therapy as definitive first-line treatment, not oral antibiotics. 1

Diagnostic Criteria

• Rapid onset (within 48 hours) in the past 3 weeks 1
• Symptoms: Severe otalgia (often disproportionate to visual findings), itching, fullness, with or without hearing loss or jaw pain 1
• Hallmark sign: Intense tenderness of tragus or pinna on manipulation 1
• Physical findings: Diffuse ear canal edema, erythema, with or without otorrhea, regional lymphadenitis, tympanic membrane erythema, or cellulitis of pinna 1

Causative Organisms

• Bacterial (98% of cases): Pseudomonas aeruginosa (20-60%) and Staphylococcus aureus (10-70%), often polymicrobial 1, 2
• Other gram-negative organisms cause only 2-3% of cases 1, 2
• Fungal involvement is distinctly uncommon in primary acute otitis externa but may occur after prolonged topical antibiotic use, in diabetics, or immunocompromised patients 1, 3

First-Line Treatment Algorithm

Step 1: Aural Toilet (Essential Pre-Treatment)

• Remove all debris, cerumen, and inflammatory material using gentle suction, dry mopping, or irrigation with body-temperature water/saline 3
• Critical caveat: In diabetic or immunocompromised patients, use only atraumatic suctioning under microscopic guidance—avoid irrigation as it can trigger necrotizing otitis externa 3
• Place compressed cellulose wick if severe canal edema prevents drop entry or tympanic membrane visualization 3

Step 2: Topical Antimicrobial Selection

• If tympanic membrane is intact: Any FDA-approved topical preparation (ofloxacin, ciprofloxacin, neomycin/polymyxin B combinations) achieves 65-90% cure rates within 7-10 days 3
• If tympanic membrane is perforated, uncertain, or tympanostomy tubes present: Use ONLY non-ototoxic fluoroquinolones (ofloxacin 0.3% or ciprofloxacin 0.2%) 1, 3
• If history of contact dermatitis or eczema: Avoid neomycin-containing preparations (cause sensitivity in 13-30% of chronic otitis externa patients); use fluoroquinolone-only drops 3

Step 3: Proper Drop Administration

• Warm bottle in hands 1-2 minutes to prevent dizziness 3
• Have someone else administer drops if possible (only 40% self-administer correctly) 3
• Lie with affected ear upward, fill canal completely, maintain position 3-5 minutes 3
• Apply gentle to-and-fro movement of pinna or tragal pumping to eliminate trapped air 3
• Continue for minimum 7 days even if symptoms resolve early 3

Step 4: Pain Management

• Assess pain severity and prescribe appropriate analgesics (acetaminophen or NSAIDs for mild-moderate pain; short-term opioids for severe pain during initial 48-72 hours) 1, 3
• Pain typically improves within 48-72 hours of starting topical therapy 1, 3
• Avoid topical anesthetic drops (benzocaine)—not FDA-approved for active infections and can mask treatment failure 3

When to Use Systemic Antibiotics

Oral antibiotics should NOT be used as initial therapy for uncomplicated acute otitis externa. 1, 3 Reserve for:

• Extension of infection beyond ear canal (periauricular cellulitis) 1, 3
• Diabetes mellitus 1, 3
• Immunocompromised state 1, 3
• Prior radiotherapy 1
• Topical therapy cannot reach infected area 3
• Treatment failure after 48-72 hours 3

When indicated, use fluoroquinolones (ciprofloxacin) for coverage against P. aeruginosa and S. aureus 3

Treatment Failure: Reassess at 48-72 Hours

Consider these causes if no improvement: 3

• Inadequate drug delivery (canal obstruction, poor adherence)
• Allergic contact dermatitis from topical agents (especially neomycin or hydrocortisone)
• Fungal co-infection (otomycosis)
• Incorrect diagnosis

Fungal Otitis Externa (Otomycosis)

Suspect fungal infection when white fuzzy exudate with pruritus predominates, or when bacterial treatment fails—particularly in diabetic, immunocompromised patients, or after prolonged topical antibiotic use. 4

Distinguishing Features from Bacterial Otitis Externa

• Pruritus is the predominant symptom (vs. severe pain in bacterial) 4
• White fuzzy or black debris visible on examination 3, 4
• Often follows prolonged antibacterial therapy 1, 4
• More common in tropical/humid climates, diabetics, immunocompromised 2

Causative Organisms

• Aspergillus and Candida species are primary fungal pathogens 2
• Black fungal debris highly suggestive of Aspergillus 3

Treatment Approach

• Thorough but gentle debridement of fungal debris under microscopic visualization 3, 4
• Topical antifungal preparations (azole cream or boric acid irrigating solutions) 3-4 times daily for 7-10 days 3, 4
• Avoid antibacterial drops that promote fungal overgrowth 1, 3
• Systemic azoles for refractory cases or perforated tympanic membranes 3

Necrotizing (Malignant) Otitis Externa

High-risk patients (elderly, diabetic, immunocompromised) require urgent ENT evaluation and aggressive management due to risk of necrotizing otitis externa. 3

High-Risk Features

• Diabetes mellitus with hyperglycemia 3
• Immunocompromised state 1, 3
• Elderly patients 3
• Prior radiotherapy 1

Management Modifications for High-Risk Patients

• Avoid ear canal irrigation—use only atraumatic suctioning under microscopic guidance 3
• Monitor carefully for progression to necrotizing otitis externa 3
• Consider adding systemic antipseudomonal antibiotics even for seemingly uncomplicated cases 3
• Aggressive surgical debridement of necrotic tissue if necrotizing otitis externa develops 3

Allergic Contact Dermatitis of External Ear

Allergic contact dermatitis presents as persistent erythema, pruritus, edema, and otorrhea despite treatment—most commonly from neomycin (13-30% of chronic otitis externa patients). 3

Common Sensitizers to Avoid

• Neomycin (most common: 5-15% of patients) 3
• Bacitracin, polymyxin B sulfate 3
• Hydrocortisone, triamcinolone 3
• Benzocaine, propylene glycol, thimerosal 3

Management

• Discontinue offending agent 3
• Switch to fluoroquinolone-only drops 3
• Consider patch testing for recurrent cases 3

Non-Inflammatory Diseases of the External Ear

Cerumen Impaction

Cerumen impaction causes canal obstruction and must be removed before administering topical therapy to ensure medication reaches infected tissues. 3

Removal Techniques

• Gentle suction 3
• Dry mopping 3
• Irrigation with body-temperature water, saline, or hydrogen peroxide 3
• Avoid irrigation in diabetic/immunocompromised patients or suspected perforation 3

Dermatologic Conditions (Eczema, Seborrhea, Psoriasis)

For patients with eczema, seborrhea, or psoriasis affecting the ear canal, distinguish between primary dermatologic condition and bacterial superinfection. 3

Management Algorithm

• If dermatologic condition is primary: Apply topical corticosteroid drops or ointments for 7-10 days 3
• If bacterial superinfection present: Use fluoroquinolone drops first to avoid neomycin sensitization, then add topical corticosteroid only after bacterial infection controlled 3

Foreign Body

Foreign bodies require removal under direct visualization before treatment can proceed 5

Common Pitfalls to Avoid

• Prescribing oral antibiotics for uncomplicated cases (occurs inappropriately in 20-40% of patients) 3
• Using ototoxic preparations (aminoglycosides) when tympanic membrane integrity is compromised 1, 3
• Inadequate pain management—pain can be severe and requires appropriate analgesics 1, 3
• Failure to remove debris before administering drops—medication cannot penetrate through obstruction 3
• Missing fungal infections in treatment failures, especially diabetics 3
• Prescribing neomycin-containing drops in patients with eczema, chronic otitis externa, or contact dermatitis history 3
• Irrigating ear canal in diabetic or immunocompromised patients 3
• Using ear candles—never effective but have caused hearing loss and tympanic membrane perforation 3

Prevention Strategies

• Avoid water exposure to affected ear during treatment 3, 5
• Keep ear dry—use earplug or petroleum jelly-coated cotton before showering 3
• Avoid inserting cotton swabs or objects into ear canal 3, 5
• Dry ears with hair dryer after water exposure 5
• Acidification with 2% acetic acid after moisture exposure for prophylaxis 5