Acute otitis externa is a diffuse inflammation of the external ear canal that is most commonly caused by Pseudomonas aeruginosa and Staphylococcus aureus.
Presents with rapid onset of ear pain, tenderness, itching, aural fullness, and hearing loss.
The development of malignant or necrotising otitis externa is more common in diabetic and immunocompromised people.
Treatment of the uncomplicated form is cleaning of the ear canal and application of topical anti-infective agents.
Acute otitis externa (AOE) is defined as diffuse inflammation of the external ear canal, which may also involve the pinna or tympanic membrane. It is a form of cellulitis that involves the skin and subdermis of the external auditory canal, with acute inflammation and variable oedema. It is most commonly caused by bacterial infection with Pseudomonas aeruginosa or Staphylococcus aureus. National guidelines state that a diagnosis of AOE requires the presence of rapid onset (generally within 48 hours) of symptoms within the past 3 weeks, coupled with signs of ear canal inflammation.
History and exam
Key diagnostic factors
- presence of risk factors
- ear pain
- tenderness over the tragus, pinna, or both
- ear canal swelling and erythema
- granulation tissue in the ear canal (malignant otitis externa)
Other diagnostic factors
- aural fullness
- decreased hearing
- pain intensified by jaw motion
- erythematous tympanic membrane
- cellulitis of the pinna and adjacent skin
- external auditory canal obstruction
- high environmental humidity
- warmer environmental temperatures
- local trauma
- chemical irritants
- skin disease
- prolonged use of topical antibacterial agents
1st investigations to order
- pneumatic otoscopy
Investigations to consider
- ear culture
- microscopy of exudate/debris from ear canal
- CT scan of the temporal bone with intravenous contrast
- MRI of the brain and internal auditory canals (with and without gadolinium)
- erythrocyte sedimentation rate (ESR)
Soha Ghossaini, MD, FACS
Ear, Nose and Throat Associates of New York
SG declares that she has no competing interests.
Peter S. Roland, MD
Professor Neurological Surgery
Chief of Pediatric Otology
Otolaryngology Head and Neck Surgery
UT Southwestern Medical Center
PSR has acted as a consultant to Alcon laboratories, makers of Ciprodex®, who have provided compensation to the University of Texas Southwestern Medical Center Department of Otolaryngology Head and Neck Surgery. PSR has received compensation for speaking and for organizing educational events. PSR is co-author of the American Academy of Head and Neck Surgery's practice guideline for AOE. PSR is an author of references cited in this topic.
Anthony Wright, LLM, DM, FRCS
Emeritus Professor of Otolaryngology
UCL Ear Institute
AW declares that he has no competing interests.
Desmond A. Nunez, MD, FRCS(ORL)
Director ENT Unit
North Bristol NHS Trust
Honorary Reader in Otolaryngology
University of Bristol
DAN declares that he has no competing interests.
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