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Otitis Externa

BASICS

Description

  • Inflammation of the external auditory canal
    • Acute diffuse otitis externa (AOE): Most common form (<6 weeks), usually bacterial (Pseudomonas aeruginosa, Staphylococcus aureus); can be fungal.
    • Chronic otitis externa: >3 months, often due to chronic skin conditions, allergies, or inadequately treated AOE.
    • Eczematous otitis externa: Associated with skin disorders (eczema, seborrhea, psoriasis).
    • Malignant (necrotizing) otitis externa: Extension into deeper tissues, can be life-threatening (emergency), especially in diabetics/immunosuppressed.

EPIDEMIOLOGY

  • Incidence: ~1% annually, higher in summer/warm, wet climates; peaks at ages 7–12.
  • Prevalence: Lifetime risk ~10%.

ETIOLOGY & PATHOPHYSIOLOGY

  • Skin/cerumen barrier protects canal; disruption (water, trauma, devices) leads to infection.
  • Bacteria (>90%): P. aeruginosa (22–62%), S. aureus (11–34%), often polymicrobial.
  • Fungi (<10%): Chronic, mostly Aspergillus or Candida.
  • Chronic: Persistent allergies, chronic skin disease, inadequate treatment.
  • Eczematous: Eczema, seborrhea, psoriasis, contact dermatitis.
  • Malignant: Pseudomonas, MRSA; usually in elderly, diabetics, immunocompromised.

RISK FACTORS

  • Water exposure (swimming)
  • Humid/hot weather, sweating
  • Canal trauma (scratching, cleaning, devices)
  • Foreign body, anatomic abnormalities
  • Skin disease, cerumen buildup, excessive hair
  • Previous ear surgery/radiation
  • Advanced age, diabetes, immunosuppression (for malignant OE)

GENERAL PREVENTION

  • Avoid prolonged moisture exposure; dry canal with hair dryer on low or head-tilt
  • No self-trauma (cotton swabs, instruments)
  • Manage predisposing skin/systemic conditions
  • Ear plugs for swimming

DIAGNOSIS

History

  • Symptoms: Ear pain (70%), itching (60%), fullness (22%), conductive hearing loss (~32%), +/- jaw pain
  • Onset: Rapid (<48h), <3 weeks for acute, >3 months for chronic
  • Risk factors: Swimming, trauma, diabetes, immunosuppression

Physical Exam

  • Erythema, swelling, discharge
  • Pain with manipulation of pinna/tragus (classic)
  • No/mild effusion; assess tympanic membrane integrity
  • Granulation tissue at bone-cartilage junction → suspect malignant OE

Differential Diagnosis

  • Otitis media, eczematous skin conditions, furuncle, cholesteatoma, TMJ, dental pain, malignant OE

Diagnostic Tests

  • Clinical diagnosis (history + exam)
  • Culture if refractory, immunocompromised, or concern for necrotizing OE
  • Imaging (CT/MRI/bone scan) if extension suspected

TREATMENT

General Measures

  • Clean canal (aural toilet) to improve drop delivery
  • Analgesics (acetaminophen, NSAIDs; short-term opioid rarely)

Medication

First Line (Acute Bacterial, Uncomplicated) - Ciprofloxacin/dexamethasone 0.3%/0.1%: >6 mo: 4 drops BID ×7d - Ofloxacin 0.3%: 6 mo–13y: 5 drops QD ×7d; ≥13y: 10 drops QD ×7d - Neomycin/polymyxin B/hydrocortisone: Children: 3 drops 3–4x/day; adults: 4 drops 3–4x/day ×7d (max 10d) - Acetic acid 2%: >3y: 3–5 drops q4–6h with wick, then 5 drops 3–4x/day ×7d

Complicated/Severe/Refractory/Immunocompromised - Add systemic antibiotics: Ciprofloxacin, amoxicillin, or amox/clavulanate

Chronic OE - Remove offending agents, topical/systemic steroids for inflammation

Fungal OE - Clean canal, acidifying agents (acetic acid), then topical clotrimazole 1% if needed

Malignant (Necrotizing) OE - Emergency: Hospitalize, IV antipseudomonal antibiotics, ENT referral, possible debridement

Key Considerations

  • If TM perforation: use non-ototoxic drops (ofloxacin/ciprofloxacin)
  • If canal obstructed: aural toilet and/or wick

REFERRAL/ADMISSION

  • ENT referral for severe/resistant/malignant OE, or suspected deep tissue spread
  • Admission for malignant OE (debridement + IV antibiotics)

ONGOING CARE

  • Reassess within 48–72 hours if no improvement (acute OE)
  • For chronic OE: return every 2–3 weeks for cleaning

PROGNOSIS

  • Most acute/chronic cases resolve with cleansing and topical therapy
  • Malignant OE requires hospitalization; can cause osteomyelitis, cranial nerve palsy

COMPLICATIONS

  • Malignant OE → osteomyelitis, CNS infection, cranial nerve palsy (life-threatening)
  • Acute OE → chondritis of pinna

ICD-10 Codes

  • H60.523: Acute chemical otitis externa, bilateral
  • H60.593: Other noninfective acute otitis externa, bilateral
  • B37.84: Candidal otitis externa

Clinical Pearls

  • For uncomplicated AOE, topical therapy with or without corticosteroids is first-line
  • For known/suspected TM perforation, use only non-ototoxic drops (ofloxacin/ciprofloxacin)
  • Wick/aural toilet if canal obstructed
  • Systemic antibiotics only if infection spreads beyond canal, patient has major risk factors, or topical therapy fails
  • Malignant otitis externa = emergency; refer and hospitalize urgently