Acute diffuse otitis externa is the most common form of otitis externa, typically seen in swimmers; it is characterized by rapid onset (generally within 48 hours) and symptoms of external auditory canal inflammation (eg, otalgia, itching, fullness). Other symptoms include tenderness of the tragus or pinna, diffuse ear edema, regional lymphadenitis, tympanic membrane erythema, and cellulitis of the pinna.
Otitis externa usually represents an acute bacterial infection of the skin of the ear canal (most commonly attributable to Pseudomonas aeruginosa or Staphylococcus aureus) but can also be caused by other bacteria, viruses, or a fungal infection (Candida or Aspergillus).
Necrotizing (malignant) otitis externa is an infection that extends into the deeper tissues adjacent to the external auditory canal; it primarily occurs in adult patients who are immunocompromised (eg, as a result of diabetes mellitus or AIDS) and is rarely described in children. It may result in cases of cellulitis and osteomyelitis.
The key physical finding of otitis externa is pain upon palpation of the tragus (anterior to ear canal) or application of traction to the pinna (the hallmark of otitis externa). The tympanic membrane may be difficult to visualize and may be mildly inflamed, but it should be normally mobile on insufflation. Eczema of the pinna may be present. By definition, cranial nerve involvement (ie, of cranial nerves VII and IX-XII) is not associated with simple otitis externa.
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Cite this: Richard H. Sinert. Fast Five Quiz: Drowning and Water-Related Health Concerns - Medscape - May 13, 2022.