Differentials
Acute otitis media
SIGNS / SYMPTOMS
Acute otitis media and acute otitis externa (AOE) present with ear pain. Hearing loss may be present in both. The tympanic membrane may be erythematous in AOE, making it more challenging to rule out either an associated acute otitis media or acute otitis media alone.
Furunculosis
SIGNS / SYMPTOMS
Furunculosis is sometimes referred to as 'localised acute otitis externa (AOE)'.[1] It usually represents a localised infected hair follicle in the cartilaginous portion of the ear canal.[23] The presenting symptoms are similar to those of diffuse AOE. It presents with otalgia and tenderness.
On physical examination, the infection is confined to the cartilaginous portion of the ear canal.[3] The bony (medial) portion of the external auditory canal is usually normal.
INVESTIGATIONS
No differentiating tests.
Contact dermatitis of the ear canal
SIGNS / SYMPTOMS
This is an allergic reaction to antigens that could be present in hearing aid material, cosmetics, and other topical otic solutions. Patients usually give a history of prior use of topical solutions.
Among the topical solutions, neomycin is the most commonly implicated agent.[1] Patients with allergies to otic topical solutions usually present with erythema and oedema that extend into the conchal bowl.
INVESTIGATIONS
No differentiating tests.
Viral infections of the external ear
SIGNS / SYMPTOMS
Viral infections of the external ear, caused by varicella, measles, or herpes virus, are rare but important differentials of acute otitis externa.[1]
Severe otalgia, facial paralysis or paresis, taste disturbance on the anterior two-thirds of the tongue, and decreased lacrimation on the affected side.[1] Physical examination may reveal erythema and/or vesicles in the ear canal and auricle.[3]
INVESTIGATIONS
No differentiating tests.
Chronic otitis externa
SIGNS / SYMPTOMS
Chronic otitis externa is chronic inflammation of the ear canal skin for 3 months or longer.[12] It usually presents with diffuse low-grade infection of months' or, at times, years' duration.[13] It is the result of recurrent otitis externa, bacterial or fungal infections, underlying skin conditions, or otorrhoea from middle ear infections.[3] Patients usually present with itching and scant otorrhoea but no pain.[13]
Physical examination of the ear varies, depending on the severity of the infection, and can range from dry skin to granulation tissue.[13]
INVESTIGATIONS
No differentiating tests.
Cancer of the external auditory canal
SIGNS / SYMPTOMS
Recalcitrant to usual medical therapy.
INVESTIGATIONS
Biopsy of the external auditory canal.[1]
Cholesteatoma
SIGNS / SYMPTOMS
Consider particularly in recalcitrant disease not responding to medical therapy. Otoscopy typically shows crust or keratin in the attic (upper part of the middle ear), the pars flaccida, or the pars tensa (usually posterior superior aspect), with or without a perforation of the tympanic membrane.
INVESTIGATIONS
CT can help with confirming the diagnosis, assessing disease extension, and treatment planning.
Ear canal cholesteatoma
SIGNS / SYMPTOMS
Rare disease of the external auditory canal. It usually presents with ear discharge, focal erosion, and keratin accumulation in the bony ear canal.[24]
INVESTIGATIONS
CT may reveal a localised cholesteatoma, with or without extension into the middle ear or mastoid cavity.
Eczema (atopic dermatitis)
SIGNS / SYMPTOMS
Eczema is an inflammatory skin condition characterised by dry, pruritic skin with a chronic relapsing course. It can affect all age groups, but it is most commonly diagnosed before 5 years of age and affects 10% to 20% of children.[25] Patients often have a personal or family history of other atopic diseases such as asthma or allergic rhinitis. Food allergies may occur at increased rates in this population. Eczema can be described as acute or chronic. Acute eczema is used to describe a flare-up of symptoms. Chronic is used to describe the condition when the patient develops signs of chronic inflammation (e.g., lichenification).
INVESTIGATIONS
No differentiating tests; diagnosis of eczema is primarily clinical.
Seborrhoea (seborrhoeic dermatitis)
SIGNS / SYMPTOMS
Seborrhoeic dermatitis is a chronic inflammatory skin disorder characterised by erythematous and greasy scaly patches. Patches are red, inflamed, and pruritic with micaceous scale. Circumscribed patches are found on the scalp, glabella, nasolabial fold, posterior auricular skin, and anterior chest. Variable course that seldom completely subsides. An infant form (cradle cap) usually resolves within the first few months of life. Tends to flare with stress.[26] The adult scalp form is commonly termed dandruff or pityriasis capitis.
INVESTIGATIONS
No differentiating tests, diagnosis of seborrhoea is primarily clinical.
Chronic suppurative otitis media
SIGNS / SYMPTOMS
Chronic suppurative otitis media is suggested by chronic or intermittent otorrhoea over a period of weeks to months, especially with a non-intact tympanic membrane.[12]
INVESTIGATIONS
No differentiating tests.
Otitis media with effusion
SIGNS / SYMPTOMS
Otitis media with effusion (OME; also known as glue ear) typically presents with hearing loss, ear pressure or discomfort, or ear blockage without symptoms of acute infection. Signs/symptoms include middle ear effusion, no sign of acute infection, aural fullness or pressure, hearing loss, failed hearing screen, speech delay, signs of ear discomfort, and low progress in an educational setting.
INVESTIGATIONS
Pneumatic otoscopy: decreased movement of tympanic membrane on air insufflation when there is effusion in the middle ear.
Tympanometry: typically a flat (type B) curve (low compliance) if OME is present; a type C curve, which suggests negative pressure, may be seen.
Audiology: may show moderate conductive hearing loss.
Temporomandibular disorders
SIGNS / SYMPTOMS
Temporomandibular disorders (TMDs) comprise several painful disorders involving the mandibular joint and muscles of mastication.[27][28] TMDs typically present with four characteristic features: temporomandibular joint pain, noise in the joint, masticatory muscle tenderness, and limited mandibular movement. TMDs are a common cause of referred otalgia.[1]
INVESTIGATIONS
No differentiating tests; diagnosis of TMDs is primarily clinical.
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