xRead - January 2023

344 Otology and neuro-otology

drops [17], whereas another found voriconazole to have more potent in-vitro activity than itraconazole against all Aspergillus species and Candida albicans (all species were resistant to fluconazole in this study) [19 ]. Some patients may require close follow-up for repeated meticulous cleanings under binocular microscopy. An excellent, very effective ‘home remedy’ for persistent otomycosis is a 1 : 1 mixture of isopropyl (rubbing) alcohol and acetic acid (white vinegar; not to be used in a patient with a tympanic membrane perforation). A dropper is useful to place 3–4 drops twice a day for a week. The alcohol removes water and moisture in the canal; the acetic acid lowers the pH of the canal, making it inhos pitable for fungal organisms. Patients are warned that the mixture is very effective but they may smell like a crouton in a salad! As with any acute or chronic ear canal process, dry ear precautions and Q-tip cessation are mandatory. Dermatophytid reaction In patients whose COE is refractory to conventional therapy of debridement, ototopical drops, and/or steroid creams, a low-grade fungal infection elsewhere in the body (e.g. onychomycosis) can set up an inflammatory, allergic reaction in the ear canals. The true incidence of this process is unknown, but it can be easily screened (by exploring other possible areas of fungal infection in the patient such as the nails, scalp, or skin) and often successfully treated. Conditions necessary for a dermatophytid reaction include a primary fungal infection remote from the dermatophytid reaction (e.g. finger/toenails), absence of fungi at the dermatophytid reaction site (ears), resolution of the inflam mation when the primary fungal infection has been era dicated, and a type I Gel and Coombs (IgE) intradermal skin response to the fungal antigen. Elevated serum IgE level is also a good indicator of the role of atopy in the patient’s disease. Most common fungi – TOE (Tricho phyton, Candida, and Epidermophyton) – can be easily treated with either topical or systemic antifungals. If a dermatophytid reaction is diagnosed as the cause of COE, treatment is initially aimed at the primary fungal infection. Since the reaction in the ears is an allergic reaction, allergy management is critical. Frontline therapy for any allergic patient is environmental control. Yeast elimination diet has been strongly advocated [11]. Medical therapy involves meticulous debridement and topical steroids. Betamethasone 0.1% cream, triamcino lone cream, clobetasol, and fluocinolone acetonide oil 0.01% have been advocated. Finally, for refractory patients, especially with high serum IgE, immunotherapy has been shown to be successful [11,20].

Chronic (medial) fibrosing otitis externa A subset of patients, including children [21], with COE will show unrelenting progression of inflammation in the medial canal. After years of cleaning, topical therapy, even systemic therapy, the inflammatory pro cess becomes fibrotic, causing a thickening and scarring of the tympanic membrane and medial canal skin. Computed tomography (CT) imaging shows complete, circumferential opacification of the medial ear canal – a fibrous plug – with a perfectly aerated middle ear space without bony erosion (Fig. 3). This stage – the end result – is characterized by the resolution of the inflammation and drainage with a clean, dry, blind ending ear canal with a mild-to-moderate conductive hearing loss. Surgery is typically not advisable in the acute inflamma tory stage; a technically skillful operation with an initially promising result may succumb to the same inflammatory process. In addition, repair of medial fibrosing otitis externa secondary to a systemic autoimmune disorder (e.g. sarcoidosis) may also fail over time. After years of drainage, drops, and debridement, most patients are so happy to have a dry ear, the conductive hearing loss is not as big an issue. With a dry canal, a conventional hearing aid or a bone anchored hearing aid may offer quite adequate hearing rehabilitation. Should surgery be undertaken, most authors agree that the entire fibrous plug and all involved skin must be removed with formal canalplasty, followed by resurfacing with epithelium, most commonly, a split thickness skin graft [22–24]. One group of authors recommended aggressive treatment of methicillin-resistant Staph. aureus (MRSA) infection with vancomycin both preoperatively and at least

Figure 3 Coronal computed tomography showing the ‘fibrous plug’ at the medial end of the ear canal – opacification up to the medial aspect of the tympanic membrane sparing the aerated middle ear space

Courtesy of Prashant Raghavan, MD, Division of Neuroradiology, Department of Radiology, University of Virginia.

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