Otitis Externa

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Eczema of the meatus and pinna (see Fig. 2.41) may be associated with eczema elsewhere, particularly in the scalp, or it may be an isolated condition affecting only one ear. Itching is the main symptom, with scanty discharge. The eczematous type of otitis externa usually settles with the use of a topical corticosteroid and antibiotic drop. Cleaning of the meatus may also be necessary, either with cotton wool on a probe, or suction and the Zeiss microscope. Otitis externa tends to recur.

The patient should avoid over-diligent cleaning of the meatus, or scratching the ear with the finger, probes, or cotton wool buds. Cotton wool buds, if used, should only be used to the orifice of the meatus. Water entering the ear during washing or swimming also predisposes to the recurrence of otitis externa.

Otitis Externa Bullosa

Fig. 2.42 A furuncle in the meatus is the other common type of otitis externa. It is characterized by pain; pain on movement of the pinna or on inserting the auriscope is diagnostic of a furuncle. Diabetes mellitus must be excluded with recurrent furuncles.

Fig. 2.41 Eczematous otitis externa.

Eardrop sensitivity may worsen an otitis externa. Chloramphenicol drops caused this condition. Neomycin less commonly causes similar reactions. Patients should be advised to discontinue eardrops that cause an increase in irritation or that are painful.

Fig. 2.42 A furuncle in the meatus is the other common type of otitis externa. It is characterized by pain; pain on movement of the pinna or on inserting the auriscope is diagnostic of a furuncle. Diabetes mellitus must be excluded with recurrent furuncles.

Diabetic Furnacle
Fig. 2.44 Chronic otitis externa persisting for years may eventually lead to meatal stenosis and rarely to closure of the ear canal.

Fig. 2.43 Furunculosis. This is a generalized infection of the meatal skin. Pain is severe and the canal is narrowed or occluded so that examination with the auriscope is extremely painful and no view of the deep meatus is possible. A swab of the pus should be taken, and treatment is with systemic antibiotics and a meatal dressing (e.g., glycerine and ichthyol, or a corticosteroid cream with an antibiotic).

The organism may be transferred by the patient's finger from the nasal vestibules, and a nasal swab is a relevant investigation, particularly with recurrent furuncles. The lymph nodes adjacent to the pinna are enlarged with a furuncle or furunculosis, and a tender mastoid node may mimic a cortical mastoid abscess.

Mastoid Abscess Otitis Externa

Fig. 2.45a-c "Deep" otitis externa. An uncommon form of chronic otitis externa involves predominantly the skin of the deep bony meatus and the surface of the tympanic membrane. The drum epithelium may become replaced with sessile granulations (granular myringitis) infected with Pseudomonas pyocyanea.

In protracted cases of this type of otitis externa, the skin of the deep mea-tus and drum becomes thickened and "funneled" with meatal atresia. The resulting conductive hearing loss is extremely difficult to treat surgically once this condition is quiescent.

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Fig. 2.46 "Malignant" otitis externa is a rare and serious form of otitis externa to which elderly diabetics are particularly susceptible. Granulation tissue is found in the meatus infected with Pseudomonas and anaerobic organisms. This granulation tissue tends to erode deeply, involving the middle and inner ear, the bone of the skull base with extension to the brain, and also the great vessels of the neck. If uncontrolled, the condition may be fatal.

Intense antibiotic therapy sometimes associated with surgical drainage of the affected areas is necessary. It is not a "malignant" condition in the histological sense, for the biopsies of granulation tissue show inflammatory changes only. "Necrotizing" otitis externa may be more accurate, but "malignant" indicates the serious clinical nature.

Fig. 2.47 Otitis externa secondary to discharge via a drum perforation is initially treated (an ear swab having been taken for culture and sensitivity) with cleaning of the meatus and the instillation of the appropriate antibiotic and corticosteroid drops. If the condition persists with marked irritation and pain, a fungal otitis externa should be suspected. In persistent infection, the meatus contains a cocktail of drops, pus, and desquamated skin. In fungal infections, as shown here, the dark spores of Aspergillus niger and white mycelium of Candida albicans can be seen. Thorough cleaning of the meatus precedes treatment with a topical antifungal agent.

The meatal skin infection is introduced from outside—usually from the patient's finger, or from water, particularly after swimming.

The infection, however, may be from the middle ear if there is a perforation, and discharge from chronic otitis media may be the cause of a persistent otitis externa. Otitis externa rarely damages the tympanic membrane. With fungal otitis externa, however, and the presence of a granular myringitis, a perforation may ensue.

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Fig. 2.48 Bullous otitis externa (bullous myringitis). This unusual otitis externa frequently follows influenza or an upper respiratory tract infection. A complaint of earache followed by bleeding, then followed by relief of pain is diagnostic of this condition.

Examination shows hemorrhagic blebs on the drum and meatus, similar to the vesicular eruption of herpes. If there is pyrexia with a conductive hearing loss, the otitis externa is associated with an otitis media, and systemic antibiotics are necessary. In the absence of pyrexia and hearing loss, this condition settles spontaneously without treatment.

Fig. 2.49 Otitis externa with herpes zoster. Otitis externa occurs with herpes zoster (see Fig. 2.29c) involving either the gasserian or geniculate ganglion, and the vesicles may be hemor-rhagic.

Carcinomas and melanomas in the skin of the external auditory meatus are rare, but any persistent granulation or skin lesion should be biopsied.

Fig. 2.50 Osteomas. White, bony, hard swellings in the deep meatus are a common finding during routine examination. They usually remain small and symptom free, and tend to be symmetrical in both ears.

Swimmers are susceptible to these lesions, which are sometimes called "swimmer's osteomas." There is experimental evidence to show that irrigation of the bony meatus with cold water produces a periostitis that leads to osteoma formation. Histologically, these bony lesions are hyperostosis, rather than a bony tumor, so that the term "osteoma," although established, is not strictly correct.

Fig. 2.51 Large osteomas may narrow the meatus to a chink so that wax accumulates and is difficult to syringe. Otitis externa is also a complication.

These osteomas, therefore, may require surgical removal with a microdrill. They should not be removed with a gouge, for a fracture with bleeding in the remaining osteoma is a probable complication, causing damage to the facial nerve and resulting in facial palsy.

It is rare for osteomas to occlude the meatus completely, and in almost all cases no treatment is required.

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