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THE EAR

INFECTIONS OF THE EAR

1. Acute Otitis Externa

ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES

  • Rapid onset of symptoms within in the past 3 weeks.

  • Symptoms of ear canal inflammation, including otalgia, itching, or fullness, with or without hearing loss or jaw pain.

  • Signs of ear canal inflammation, including tenderness of the tragus and/or pinna, ear canal edema and/or erythema, otorrhea, regional lymphadenitis, tympanic membrane (TM) erythema, or cellulitis of the pinna and adjacent skin.

Differential Diagnosis

Acute or chronic otitis media with eardrum rupture, furunculosis of the ear canal, herpes zoster oticus, mastoiditis, referred temporomandibular joint pain, and chronic otitis externa.

Pathogenesis

Otitis externa (OE) is a cellulitis of the soft tissues of the EAC, which can extend to surrounding structures such as the pinna, tragus, and lymph nodes. Humidity, heat, and moisture in the ear are known to contribute to the development of OE, thus it is more common in the summer months. Cerumen serves as a hydrophobic protective barrier to the underlying skin and its acidic pH inhibits bacterial and fungal growth. Trauma to the ear canal skin can break this skin-cerumen barrier, which is the first step in developing OE. Sources of trauma include cotton swab use, earbuds, digital manipulation (scratching), and ear plugs. Dermatologic conditions such as atopic dermatitis can also be a risk factor for OE. The most common organisms causing OE are Staphylococcus aureus (8%), Staphylococcus epidermidis (9%), and Pseudomonas aeruginosa (38%). However, anaerobic bacteria are found in 4%–25% of patients.

Clinical Findings

Symptoms include acute onset of pain, aural fullness, decreased hearing, and sometimes itching in the ear. Symptoms tend to peak within 3 days. Manipulation of the pinna or tragus causes considerable pain. Discharge may start out as clear then become purulent and may also cause secondary eczema of the auricle. The ear canal is typically swollen and narrowed, and the patient may resist any attempt to insert an otoscope. Debris is present in the canal, and it is usually very difficult to visualize the TM due to canal edema. However, it is important to determine the status of the eardrum because if there is a perforation, this is likely the cause of inflammation in the canal and may need to be managed differently, as an acute otitis media (AOM).

Complications

If untreated, cellulitis of neck and face may result. Immunocompromised individuals can develop malignant OE, which is a spread of the infection to the skull base with resultant osteomyelitis. This is a life-threatening condition and should be evaluated with a fine-cut temporal bone computed tomography (CT) scan.

Treatment

Management of OE includes pain control, removal of debris from the canal, topical antimicrobial therapy, and avoidance of causative factors. Cultures ...

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