Diagnosis

Otitis externa

Etiology

Cause [m9u][vhv][gd7][ccv]

• Infection (98%): Pseudomonas (20-60%), Staphylococcus aureus (10-70%), Streptococcus, Candida

• Allergy/eczema: Neomycin eardrops, topical antimicrobials, topical steroids, topical anesthetics, preservatives in topical otic medications: propylene glycol, thimerosal, benzalkonium chloride, benzethonium chloride, and methyl-p-oxybenzoate

• Dermatological disease: dermatitis (atopic, seborrheic, or contact), psoriasis, dermatomycosis, or acne

Pathophysiology [vhv]

1. The external auditory canal is covered by hair follicles and cerumen-producing glands

2. Cerumen provides an acidic protective barrier that inhibits bacterial and fungal growth

3. Disruption of the normal pH and protective factors within the auditory canal:

   • Disrupted skin integrity (trauma, excessive or aggressive cleaning)

     Insufficient protective acidic cerumen production --> Risk of infection

   • Blockage of the ear canal due to cerumen

     Persistent water in the ear canal (moisture and higher pH) --> Risk of infection

Risk factors [ccv]

• Swimming

• Humidity

• Trauma or external devices (cotton swabs, earplugs, hearing aids)

• Dermatologic conditions such as eczema and psoriasis

• Narrow external ear canals

• Ear canal obstruction (cerumen obstruction, foreign body)

• Radiotherapy or chemotherapy

• Stress

• Immunocompromised patients

Complications [fac][wap][ccv]

• Periauricular cellulitis

• Malignant exernal otitis/necrotizing external otitis (diabetes, immunocompromised)

• Chronic otitis externa --> canal stenosis and hearing loss

• Myringitis

• Perichondritis

• Facial cellulitis

• Osteomyelitis of the temporal bone

Epidemiology

Incidence per 100.000 [vhv][sf9][gd7]

Approach

• Otoscopy

• Pneumatic otoscopy

• Otomicroscopy

• Tympanometry

• Acoustic reflectometry

• Culture

• Imaging studies: CT, scintigraphy

• Audiometry

Treatment

1. Prophylaxis: [vhv]

   • Maintain a healthy skin barrier

   • Limit water accumulation/moisture in the external auditory canal

   • Addressing allergy and underlying dermatitis

2. Dry aural toilet (suction, dry mopping, removal of obstructing cerumen or foreign object)

3. Non-antibiotic (antiseptic or acidifying) drops

4. Topical antibiotic three times daily for 7 days: Ciprofloxacin 0.3%

5. Steroid drops: Dexamethasone 0.05% + ramycetin 0.5% + gramicidin 0.005%

6. Fungal infection: three times daily for 7 days

   • Triamcinolone acetonide 0.1% + neomycin sulfate 0.25% + gramicidin 0.025% + nystatin 100,000 units/mL

7. Analgesics

Differential diagnoses

Bacterial tonsillitis, Cerumen, Cholesteatoma, Eczema, Foreign body, Furunculosis, Herpes zoster, Mastoiditis, Otitis media, Peritonsillar abscess, Psoriasis, Retropharyngeal abscess, Squamous cell carcinoma, Temporomandibular syndrome