xRead - January 2023

342 Otology and neuro-otology

Figure 1 ‘Dry’ chronic otitis externa characterized by scaly, flaky, pruritic, erythematous ear canal skin that can extend to the concha, sometimes ascribed to seborrheic dermatitis

Chronic otitis externa may be associated with middle ear disease that causes chronic drainage through a tympanic membrane perforation (chronic suppurative otitis media) or a wet, draining mastoid cavity. It has also been associ ated with cerebrospinal fluid otorrhea [2] and a salivary fistula through a patent foramen of Huschke [3 ]. Systemic disorders such as amyloidosis [4 ], sarcoidosis [5], Sjo¨gren’s disease [6], Wegener’s granulomatosis [7], or atopy [8–10] can underlie COE, or it may be an isolated condition. In general, treatment is aimed at quelling the inflammatory activity in the skin, removing any inciting factors, and searching for causative factors that predispose or exacer bate this often frustrating condition. Chronic otitis externa can wax and wane for years, and a subset of patients will develop chronic fibrosing otitis externa, a condition in which the epithelium of the medial ear canal and tympanic membrane undergo con tinuous, progressive deposition of fibrous tissue/scar, with the end result a blind ending canal with a moderate conductive hearing loss. Cause The cause of COE is unknown and may be multifactorial. Inflammation, rather than true infection, is characteristic, but the cause of the inflammatory response is idiopathic. The association of COE with allergic disease, contact dermatitis, and other systemic autoimmune disorders The goal of treatment is control of the inflammation by removing any offending agents (including Q-tips and water), controlling systemic autoimmune pro blems, careful debridement, and topical therapy. A multitude of topical therapies have been advo cated, including chloromycetin-sulfanilamide-fun gizone-hydrocortisone (CSF-HC) powder, topical steroid creams of varying potency, antibiotic-steroid ototopical preparations, immunosuppressive agent (e.g. tacrolimus) and alcohol-acetic acid drops; find ing one that works for each patient is key. Bacteriophage therapy and protease therapy hold promise in the future for controlling this often frustrating condition. Key points The diagnosis of chronic otitis externa (COE) must be differentiated from acute otitis externa and malignant (necrotizing) otitis externa/skull base osteomyelitis; pain is not a typical feature of COE, but pruritis often is. Treatment of COE is aimed at identifying an underlying cause for the inflammatory skin reaction, whether systemic autoimmune disease such as Wegener’s granulomatosis, contact allergen such as neomycin, fungal infection, or fungal reaction such as the dermatophytid reaction.

Courtesy of Kenneth Greer, MD, Division of Dermatology, Department of Medicine, University of Virginia.

Figure 2 ‘Wet’ chronic otitis externa characterized by weepy, moist, erythematous ear canal skin extending out to the concha, sometimes referred to as an ‘eczematoid ear’

Courtesy of Kenneth Greer, MD, Division of Dermatology, Department of Medicine, University of Virginia.

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