The term external otitis (also known as otitis externa or swimmer’s ear) refers to inflammation of the external auditory canal or auricle, usually from infection.
●Risk factors
Risk factors for developing external otitis include swimming (or other water exposure), trauma (eg, ear scratching, cotton swabs), occlusive ear devices (eg, hearing aids, ear phones), allergic contact dermatitis (eg, due to shampoos, cosmetics), and dermatologic conditions (eg, psoriasis).
●Clinical features
External otitis usually presents with ear pain, pruritus, and discharge. Examination findings of external otitis include tenderness when the tragus is pushed or the auricle is pulled, as well as erythema and swelling of the external auditory canal. The otoscopic examination should also assess for otitis media, tympanic membrane perforation, and signs of other disease.
●Levels of severity
External otitis is categorized by severity as mild, moderate, or severe:
•Mild disease is characterized by pruritus, minor discomfort, and minimal canal edema
•Moderate disease is characterized by pruritus, an intermediate degree of pain, and a partially occluded canal
•Severe disease is characterized by complete canal obstruction, intense pain, periauricular erythema, adenopathy, and fever
●Diagnosis
The diagnosis of external otitis is clinical, based upon a characteristic history and physical examination. Cultures are reserved for patients with severe external otitis, immunocompromised patients, and those who do not respond to initial therapy.
●Differential diagnosis
The differential diagnosis for external otitis includes otomycosis, contact dermatitis, chronic suppurative otitis media, and ear canal carcinoma. Carcinoma of the ear canal is a rare, aggressive disease that is suggested by blood otorrhea, a friable ear canal, and failure to respond to treatment for external otitis.
●Malignant (necrotizing) external otitis
Malignant (necrotizing) external otitis occurs when external otitis spreads to the skull base (soft tissue, cartilage, and bone of the temporal region and skull). Malignant external otitis most commonly develops in older adult diabetic patients or other immunocompromised individuals. Severe pain, otorrhea, presence of granulation tissue in the canal floor, and cranial nerve palsies may be present. These patients should be promptly referred to an otolaryngologist.
