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INFECTIONS OF THE EAR
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1. Acute Otitis Externa
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ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Rapid onset of symptoms within the past 3 days.
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.
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Differential Diagnosis
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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 (OE).
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OE is a cellulitis of the soft tissues of the external auditory canal (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 and in humid climates. 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 can include cotton swab use, earbuds, digital manipulation (scratching), and ear plugs. Dermatologic conditions such as atopic dermatitis can also predispose one to OE. The most common organisms causing OE are Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. However, anaerobic bacteria are also seen. Fungal infection occurs in 2%–10% of patients, usually following treatment for a bacterial OE.
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Symptoms include acute onset of pain, aural fullness, decreased hearing, and itching in the ear. Symptoms tend to peak within 3 days. Manipulation of the pinna or tragus causes considerable pain. Discharge may be clear or purulent and may also cause secondary eczema of the auricle. The EAC is typically swollen and narrowed, and the patient may resist any attempt to insert an otoscope. Debris is often present in the canal, and it may be difficult to visualize the TM. However, it is important to determine the status of the eardrum to rule out secondary OE caused by middle ear drainage that may need to be managed differently.
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If untreated, cellulitis of neck and face may result. Immunocompromised individuals or uncontrolled diabetics 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 emergently if suspected.
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Management of OE includes pain control, removal of debris from the canal, topical antimicrobial therapy, and avoidance of causative factors. Cultures are ...