Otitis Externa

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Overview

Overview Acute otitis externa (AOE) is a common ear condition seen in the primary health care setting. Also known as ‘swimmer’s ear’ or ‘tropical ear’, it is prevalent in hot humid climates. AOE is an inflammatory condition of the ear canal skin. The causes are infective or non-infective.

Definition
Otitis externa: Inflammation of the outer ear canal, often due to bacterial or fungal/ yeast infection. Otitis externa may occur in isolation, or can be associated with AOM and perforation of the tympanic membrane.
Acute Otitis Media Acute inflammation of the middle ear characterised by otalgia, bulging tympanic membrane and erythema +/- perforation and otorrhoea
Otitis Media with effusion (Glue Ear): Also known as serous otitis media characterised by fluid in the middle with without symptoms or sign of acute inflammation of ear.

Remember AOE usually results from excessive exposure to heat and moisture and is usually very painful. Treatment involves cleaning, keeping area dry and topical antibiotics

Anatomy

Nerve	Supply
Great auricular (C2, C3)	Cranial surface of auricle and the lower part of the lateral surface of auricle
Auriculotemporal branch of the trigeminal nerve	Upper part of the lateral surface and most of the meatal skin
Facial nerve	Posterior–inferior portion of the external ear canal and adjacent tympanic membrane
Glossopharyngeal nerve tympanic branch	Mucosal surface of tympanic membrane
Vagus – auricular branch ‘Arnold’s nerve’	Supplies small areas of skin on the cranial auricular surface, posterior wall and floor of the meatus and adjoining part of the tympanic membrane

Classification

Classification of otitis externa
Infective	Bacterial	Acute diffuse
		Acute localised furunolosis
		Chronic
	Fungal	Otomycosis
	Viral	Herpes zoster oticus
	Necrotising (Bacterial/fungal)	Malignant
Non-infective	Dermatitis	Seborrhoeic
		Atopic-eczematous
		Psoriasis

Risk Factors

Water exposure
Wax
Dermatological
Trauma
Anatomical
Localised ear disease
Systemic disease - Diabetes, immunocompromised
Radiotherapy
Assistive hearing devices

Signs and Symptoms

Clinical presentation

Otalgia/pain
Oedema
Erythema
Otorrhoea
Debris in the canal
Itchiness
Hearing loss

Diagnosis

Rapid onset <48 hours in the past 3 weeks
Signs of ear canal infection
Symptoms of ear canal infection

Differential Diagnosis

Acute otitis media
Chronic otitis externa
Chronic suppurative otitis media
Contact dermatitis
Eczema
Furunculosis
Ramsay hunt syndrome

Ramsay hunt Syndrome Herpetic ulcers in canal; may have facial numbness/paralysis, severe pain, loss of taste (caused by herpes zoster - shingles)

Investigations

Pneumatic otoscopy

Aetiology

AOE is an inflammatory condition of the ear canal skin. The causes are infective or non-infective.

Infective

Viral otitis externa
Fungal otitis external (otomycosis)
Acute locatlised otitis externa (furnculosis)
Acute diffuse otitis externa

Non - Infective

Seborrhoeic dermatitis
Atopic dermatitis

Management

Paracetamol
NSAIDs
Opioid
Swab for micobiology, culture and sensitivity
Ear toilet
Topical antibiotics + steroids

Prevention

Earplugs while swimming
Hair dryers on the lowest settings
Head tilting to remove water from the ear canal
Avoidance of self-cleaning or scratching the ear canal.

Complications and Prognosis

Complications

Mastoid osteomyelitis (nectrotising otits externa)
Cranial nerve palsy - facial nerve

Prognosis

Most patients will experience considerable improvement in symptoms after one day of treatment.
If there is no improvement within 48 to 72 hours, physicians should reevaluate for treatment adherence, misdiagnosis