Conditions of the external ear
Congenital
anomalies
Congenital anomalies can range from total
absence of the ear through to mild cosmetic deformities such as tiny accessory
auricles or skin tags. External ear anomalies can be isolated or may be
associated with middle ear deformity. The external and middle ear originate from
the first and second branchial arches, whereas the cochlea is of neuroectodermal
origin. This means that an individual may have no pinna or ear canal but a
normal cochlea may well be present. In these circumstances, sound can be
transmitted from a hearing aid connected to an osteo integrated peg that is
screwed into the mastoid bone.
Children who have a significant deformity of the pinna (microtia) can be
helped with osteointegrated implants to which a prosthetic ear is connected (Fig.
40.3). The ear can be unclipped prior to playing violent sport (e.g.
rugby) and this unsettles the opposition.
Prominent
ears are a common deformity which usually results from the absence of the
antihelix curve. Various cartilage scoring methods are available to correct
this deformity.
Trauma
Trauma often affects the external ear. A
haematoma of the pinna occurs when blood collects between the penchondrium and
the cartilage. The cartilage receives its blood supply from the perichondrial
layer and will die if the haematoma is not evacuated (cauliflower ear). An
extensive excision, under general anaesthetic, with a pressure dressing and
antibiotic cover is recommended (see Fig. 40.4).
Foreign
bodies in the ear canal need to be treated with the greatest respect. If an
object is not simply removed at the first attempt, it is better to do it with
the aid of a microscope and general anaesthesia. An active 2-year-old with a
bead in the ear can be a formidable opponent (Fig. 40.5).
Inflammatory
disorders
Inflammatory disorders of the external ear are
extremely common. Otitis externa frequently presents to general practice and
to ear, nose and throat (ENT) surgeons. There is generalised inflammation of the
skin of the external auditory meatus. It can occur as an acute episode or can
run a more chronic course. The cause is often multifactorial but includes
general skin disorders, such as psoriasis and eczema, and trauma. Common
pathogens are pseudomonas and staphylococcus bacteria, and amongst fungi,
candida and aspergillus. Once the skin of the ear canal becomes soggy and
oedematous, skin migration stops and debris collects in the ear canal which acts
as a substrate for the pathogens. The hallmark of acute otitis externa is severe
pain (evidently on a par with childbirth). Unlike otitis media, movement of the
pinna elicits pain. The condition is often bilateral.
The
initial treatment is with topical antibiotics and steroid ear drops, together
with analgesia. If this fails meticulous removal of the debris with the aid of
an operating microscope is required. Regular cleaning of the canal, together
with topical steroids, needs to be continued until normal skin migration
resumes. If fungal infection is present it can easily be recognised by the
presence of hyphae and spores within the canal (Fig. 40.6). Fungal infection
causes irritation and itch, and the treatment is meticulous removal of the
fungus and any debris, as well as stopping any concurrent antibiotics.
Systemic
antibiotics are rarely required for otitis externa but should be used if
cellulitis of the pinna occurs (Fig. 40.7).
Necrotising
otitis externa is a rare but very important condition. It presents as a
severe, persistent, unilateral otitis externa in an immunocompromised
individual, for example it is important to think of the diagnosis in an elderly
diabetic. Osteomyelitis of the skull base occurs and usually the infecting
organism is Pseudomonas aeruginosa. Several
cranial nerves (VII, IX and X) may be destroyed by the progressing infection.
Intensive systemic antibiotic treatment is required
A
furuncle of the external ear is an infection of a hair follicle and is due to a
staphylococcal infection. Moving the pinna causes extreme pain. Local treatment
of the ear canal (oto-wick and steroid drops) together with systemic antibiotic
therapy is required.
Neoplasms
Benign neoplasms of the external ear are
common if osteomas are included. These arise from the bone of the ear canal in
individuals who have done a lot of swimming in cold water. No treatment is
required unless they obstruct the migration of skin out of the canal. Other
benign tumours include papillomas and adenomas.
Malignant primary tumours
Malignant primary tumours of the external ear
are either basal cell or squamous cell carcinomas (Fig.
40.8). Both may present
as ulcerating or crusting lesions which grow slowly and may be ignored by
elderly patients. Squamous cell carcinomas may metastasise to the parotid
and/or neck nodes and need radical surgical clearance. The ear canal may be
invaded by tumours from the parotid and postnasal space carcinoma which
‘creep’ up the eustachian tube. All resectable malignant tumours of the
ear are treated primarily with surgery with or without the addition of radiation
therapy.
The external ear
• Otitis externa responds to topical medication
•
Unilateral otitis externa in a diabetic may be fatal
•
Auricular haematoma needs a robust incision, drainage and pressure
dressing
•
Think osteo integration for congenital malformations