otitis externa Flashcards
what is otitis externa?
inflammation of the external ear canal
what is the difference between localised and diffuse otitis externa?
Localized otitis externa — is a folliculitis (infection of a hair follicle) that can progress to become a furuncle (boil) in the ear canal.
Diffuse otitis externa (also known as swimmer’s ear, or tropical ear) — is widespread inflammation of the skin and subdermis of the external ear canal, which can extend to the external ear and the tympanic membrane (ear drum).
when is otitis externa acute or chronic?
acute if =3 weeks
chronic if >3 months
what is malignant otitis externa?
an aggressive infection that predominantly affects people who are immunocompromised, or have diabetes mellitus, or the elderly.
Otitis externa spreads into the bone surrounding the ear canal (the mastoid and temporal bones). It is also known as necrotizing otitis.
what are the causes of acute diffuse otitis externa?
- bacterial infection e.g pseydomonas aeruginosa or staphylococcus aureus
- fungal infection e.g aspergillus or candida albicans
- contact dermatitis , can be allergic contact dermatitis or irritant contact dermatitis.
- trauma e.g scratching and cleaning
- environmental factors e.g high temp or humidity
what are the causes of chronic otitis externa?
- contact dermatitis
- fungal infection (ear canal flora are modified by prolonged and extensive use of topical anti bacterials or corticosteroids = predisposed to fungal infections)
- bacterial infections (low grade, persistent infections cause thickening of skin of in ear canal, loss of normal skin structure and reduced earwax production)
what are the risk factors for malignant otitis externa?
- DM
- compromised immunity e.g HIV/AIDS, chemo, CKD
- radiotherapy to head or neck
what are the complications of otitis externa?
- fibrosis, leading to stenosis of the ear canal and conductive deafness
- tympanic membrane perforation
- chronic otitis externa
- abscess
- malignant otitis
what are the complications of malignant otitis?
facial nerve palsy and meningitis
what are the signs of otitis externa?
- red, swollen or eczematous ear canal or external ear with the shedding of scaly skin
- later, swelling may have white or yellow centre filled with pus
- discharge (serous or purulent) may be present in ear canal
- inflamed eardrum
what are the symptoms of otitis externa?
- itch
- severe ear pain, disproportionate to size of lesion
- pain made worse when tragus or pinna is moved, or when an otoscope is inserted
- tenderness on moving the jaw
- loss of hearing if there is sufficient swelling to occlude the ear canal
what are the signs and symptoms of malignant otitis?
Signs:
- Granulation tissue at bone–cartilage junction of ear canal; exposed bone in the ear canal.
- Facial nerve palsy (drooping face on the side of the lesion).
- Temperature over 39°C.
Symptoms:
- Pain and headache, more severe than clinical signs would suggest.
- Vertigo.
- Profound hearing loss.
what are the differentials of otitis externa?
- acute otitis media
- foreign body
- impacted earwax
- cholesteatoma
- mastoiditis
- malignant otitis
- referred pain
how is localised otitis externa treated?
For pain
- analgesic
- local heat e.g warm flannel
For infection
- severe infection may warrant oral antibiotics, otherwise not indicated.
- 7 day course of flucloxacillin or clarithromycin (if penicillin allergy)
consider follow up if on oral antibiotics or patient is immunocompromised, otherwise not usually warranted
how should acute otitis externa be treated?
- manage aggravating factors
- consider cleaning external auditory ear canal if earwax or debris obstructs application of topical medicine (referral may be needed to ENT)
- Paracetamol/Iboprofen for pain
- consider topical antibiotics with/without topical corticosteroid
- ear wick may be needed if there extensive swelling (ENT referral)
- oral antibiotics are rarely indicated, unless cellulitis extends beyond external ear canal, ear canal is occluded by swelling/ debris, patient is immunocompromised, or high risk of severe infection.
