Managing Acute Otitis Externa: The Latest Guidelines

Gordon H. Sun, MD, MS

Disclosures

March 02, 2016

Predisposing and Complicating Factors

Many conditions predispose to the development of AOE. Among the most common risk factors is prolonged exposure to water, from swimming or other water-based activities, or through long-term exposure to high-humidity environments. Anatomic features (a narrowed ear canal, canal obstruction by cerumen or other means, and placement of such objects as earplugs, cotton swabs, or hearing aids in the ear canal) and dermatologic conditions (eczema psoriasis or contact irritation by otorrhea from otitis media, soap, and other agents) are among many other known risk factors for AOE.[4]

This patient demonstrated several risk factors, including use of cotton swabs in the ear, long-term hearing aid use, and diabetes. Age and sex are not considered to be significant risk factors for the development of AOE,[5] nor has hypertension been reported to be a risk factor for AOE.

The AAO-HNSF clinical practice guideline for AOE[3] highlights several special conditions that may modify the management of AOE. Patients with diabetes, HIV infection, or other immunocompromised states are particularly prone to necrotizing/malignant otitis externa and otomycosis.[3] Necrotizing otitis externa, an invasive infection of the external auditory canal and skull base, is classically reported in elderly patients with diabetes and almost always caused by Pseudomonas aeruginosa.[6] Cranial nerve involvement is sometimes present, and examination can reveal granulation tissue along the floor of the external auditory canal and at the bony-cartilaginous junction. Treatment of this condition includes surgical debridement and systemic antibiotic therapy.[3] Otomycosis, a fungal infection of the external auditory canal, is found not only in patients in immunocompromised states but also in those living in tropical, humid conditions. Symptoms include otorrhea (which can be many different colors) and pruritus. Aspergillus-related infections produce debris often described as having the appearance of "wet newspaper," whereas Candida-related infections usually are whitish-colored with hyphae. Debridement plus topical antifungal therapy is the usual treatment approach; topical antibiotic therapy may actually exacerbate the process by promoting fungal overgrowth.[3,4]

Radiation therapy produces substantial adverse effects on the external ear. The skin of the external ear can undergo acute reactions such as erythema, desquamation, and ulceration as well as delayed changes such as atrophy, ulceration, external otitis, and canal stenosis. Destruction of sebaceous and apocrine glands with reduced cerumen production can further alter the external auditory canal environment and contribute to ongoing chronic infections. Management of radiation therapy-induced external otitis can require anti-inflammatory and antimicrobial therapy.[7]

Finally, concurrent middle ear disease can affect how AOE is managed. A tympanic membrane perforation from otitis media, or the presence of tympanostomy tubes, can allow purulent secretions from the middle ear to enter the external auditory canal and irritate the skin.[3] Research also has demonstrated that middle ear or mastoid fluid from occult otitis media can be present during AOE.[8] Management of concurrent otitis media may require systemic antibiotic therapy, imaging, or surgical intervention; if ototopical medication is prescribed in patients with a non-intact tympanic membrane, caution to avoid compounds that are ototoxic (eg, neomycin/polymyxin B/hydrocortisone) or have a low pH (eg, alcohol, acetic acid) is advised.[3,4] Acute, uncomplicated otorrhea associated with tympanostomy tube placement should be managed with ototopical antibiotics only, without concurrent oral antibiotics.[9]

Third Case: Ototopical Therapy for AOE

A 17-year-old high school student presented to an urgent care clinic with severe pain and sensation of fullness of the right ear for the past week. The patient recalled noticing some yellowish drainage from the ear at the onset of symptoms but said that he had not seen any drainage in the past few days. He was otherwise healthy with no pertinent medical or surgical history. The patient denied hearing loss, tinnitus, or vertigo. He admitted to weekend consumption of beer but denied tobacco or illicit drug use. The patient had been using over-the-counter analgesics but denied using any prescribed medications or having any drug allergies. He denied antecedent trauma or swimming.

The patient was afebrile, with normal vital signs, and did not appear to be in significant distress. He reported moderate pain when the tragus of the right ear was lightly pressed. There was some difficulty examining the right ear with an otoscope owing to significant canal swelling and tenderness. The right tympanic membrane was poorly visualized, but there was a questionable presence of granulation tissue over the central portion of the eardrum. The right mastoid process was nontender. The left ear exam and the remainder of the head and neck exam were unremarkable.

The patient was diagnosed with concurrent AOE and acute otitis media with suspected tympanic membrane perforation.

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