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Ear Disorders |
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Acquired diseases of the pinna are frequently
seen in community practice.
Among the most commonly seen pinnal lesions are keloids; a firm, dermal nodule
develops in the dermis, usually following trauma.
The most common site is in the
earlobe, following ear-piercing, particularly in girls of Afro-Caribbean
origin.
Trauma to the pinna is usually the result of a violent blow, sustained during
criminal assault or its socially acceptable equivalent, boxing .
The most common
lesion is a tense, tender haematoma, incomplete resolution of which leads to
physical distortion of the pinna (cauliflower ear).
Inflammatory skin disease particularly affects the back of the pinna and the
groove behind the ear. Atopic eczema is the most common disease, particularly in
children with the atopic tendency.
Chondrodermatitis nodularis helicis presents as a small intractable and often
tender ulcer, usually on the helix. It is most common in the elderly and there
may be degeneration of the pinnal cartilage beneath the ulcerated area.
Tumours and pre-tumorous conditions mainly occur in the elderly. They are
usually squamous cell carcinomas or basal cell carcinomas (both of which tend to
be single lesions), or solar or actinic keratoses (which may be multiple).
Ear infections
There are two patterns of inflammation of the external auditory meatus (otitis
externa). Inflammation may be localized, due to a boil (furuncle) in the ear
canal, or diffuse, usually due to either bacterial or fungal infection. A common
fungus is Aspergillus niger, black threads of which can be identified in the
inflammatory exudate and may even be visible in the ear canal.Allergic otitis
externa is usually a response to topical ear drops.
Viral warts, basal cell carcinomas and squamous cell carcinomas can occur in the
external auditory meatus, but all are rare.
The external auditory meatus is inflamed and covered by a scaling exudate, which
spreads onto the pinna. Some of the pinnal changes are due to superimposed
allergic otitis, a response to antibiotic eardrops given for the original
infection.
Perforation of the tympanic membrane usually results from middle ear infection,
but may occasionally follow trauma
The tympanic membrane (eardrum) is a three-layered structure. There is a central
sheet of fibrocollagenous support tissue containing numerous elastic fibres,
covered on the external surface by stratified squamous epithelium continuous
with that of the external auditory meatus, and on the inner surface by low
cuboidal epithelium continuous with that lining the middle ear.
Infection (usually acute otitis media) is the most important cause of
perforation, particularly in children. Less commonly, trauma, e.g. sustained
during attempted removal of foreign bodies, may result in perforation. Most
central perforations of the drum heal spontaneously.
After perforation most eardrums heal by fibrosis
Although small central perforations heal spontaneously by fibrosis within a few
days, larger perforations sometimes fail to heal and may require surgical
closure using a fascial graft. A healed perforation is sometimes visible as a
white scar or thinned area on the eardrum.
The most important complications of a central perforation are: predisposition to
recurrent middle ear infection (otitis media), with impaired hearing; and
failure to heal.
Chronic suppurative otitis media usually follows permanent perforation of the
eardrum
Recurrent chronic inflammation in the middle ear is an important cause of
chronic earache, deafness, and persistent discharge from the external auditory
meatus. It usually occurs in people with a persistent, non-healing perforation
of the eardrum. Chronic suppurative otitis media (CSOM) is usually subdivided
into two broad groups:
• Tubotympanic disease, in which the perforation is in the pars tensa of the
eardrum, and the discharge is typically copious and mucopurulent. The mucosal
lining of the middle ear becomes chronically inflamed with a heavy infiltrate of
lymphocytes and plasma cells, leading to thickening and the formation of
inflammatory granulation tissue, often in the form of chronic inflammatory
granulation polyps.
• Atticoantral disease, in which the perforation is located in the eardrum at
the attic region, and is typically associated with the development of
cholesteatoma. Atticoantral disease is also associated with a higher risk of
major complications, e.g. brain abscess and other intracranial infection.
OME (glue ear) in children is commonly associated with upper respiratory tract
infections
In otitis media with effusion (OME), mucoid fluid accumulates in the middle-ear
cavity because it is unable to drain through the child's narrow Eustachian tube.
This is possibly associated with lower tube blockage due to reactive hyperplasia
of the adenoid lymphoid tissue.
The fluid is sterile, and is often thick and tenacious, resembling greyish brown
liquid glue, hence the common term 'glue ear'. It is associated with conductive
deafness with intermittent earache. Because of the stasis of the fluid within
the middle ear, there is a predisposition to acute suppurative otitis media due
to secondary bacterial infection.
Tympanosclerosis is a hyaline degeneration of the eardrum sub-mucosa. Appearing
either as a crescentic white area or as chalky-looking patches, it may occur in
the tympanic membrane in association with OME. It is most commonly seen after
insertion of a grommet.
The most important primary disease of the small bones of the middle ear is
otosclerosis
In otosclerosis the normal bone of the auditory ossicles is replaced and
thickened by newly deposited woven bone. The disease, which is usually bilateral
and eventually produces deafness, may be hereditary. There is an adult female
preponderance. The disease usually starts at the otic capsule between the
cochlea and vestibule, and may spread to involve the footplate and limbs of the
stapes. It is the involvement of the stapes and of the cochlea that leads to
deafness.
Cholesteatoma is an important middle ear disease
Cholesteatoma is a form of epidermoid cyst. Most commonly located in the
epitympanic recess (attic) and mastoid antrum, it often extends into the mastoid
process. Its precise pathogenesis is disputed, but it is frequently associated
with an atticoantral perforation of the eardrum. It is a cystic structure lined
by squamous epithelium, which constantly produces keratin. This leads to
expansion of the lesion, damaging the small structures in the cavity. The area
may become colonized by Gram-negative saprophytic bacteria, which probably
stimulate continuing keratin formation. The enlarging keratinous mass, lined by
stratified squamous epithelium, can eventually erode bone, and may destroy the
labyrinth, mastoid air cells, and facial nerve. It may even erode through the
skull forming the base of the middle cranial fossa. Although non-neoplastic,
cholesteatomas have the same effects as a slow-growing benign tumour.
Common causes of conductive deafness
Although it is usually initially unilateral, up to 50% of patients may
eventually develop disease in the other ear, sometimes many years later. Its
cause is unknown, but the most important abnormality is marked distension of the
cochlear duct by excess fluid, such that the vestibular membrane of Reissner,
which separates two fluids of different composition, bulges into the scala
vestibuli. This membrane may rupture, allowing the two fluids to mix.
Histological study of the disease is hampered by the difficulty of obtaining
untraumatized cochlea at post mortem examination.
Many diseases of the ear are associated with temporary or permanent hearing
loss
Hearing loss can be classified as conductive (usually due to some abnormality in
external or middle ear), sensorineural (usually due to some abnormality in the
inner ear, auditory nerve or brain), or mixed (i.e. with features of both
conductive and sensorineural hearing loss).
Conductive hearing loss occurs when sound waves cannot be transmitted to the
inner ear
Conductive hearing loss is the most common type of temporary hearing loss
encountered in family practice. In most cases it is due to occlusion of the
external auditory canal by wax, and the hearing improves when the wax is
carefully removed.
Sensorineural deafness is due to damage to the inner ear, or to the nerve tracts
transmitting messages to the brain
The most common type of permanent hearing loss is presbycusis, a pattern of
sensorineural hearing impairment in the elderly. There is decrease in hair cells
(associated with atrophy of the epithelial tissue in the basal turn of the
cochlea), atrophy of the stria vascularis, and neuronal loss in the spiral
ganglia, all of which lead to a progressive sensorineural hearing loss. This
type of deafness is characterized by loss of high tones combined with
distortion.
Schwannoma of the vestibulocochlear nerve is an important cause of unilateral
hearing loss. As with paraganglioma, it is more common in women than in men,
usually presenting between the ages of 30 and 50 years.
Tumours of the ear are not common, and mainly occur in the external ear
Both basal cell carcinoma and squamous cell carcinoma can originate in the
epithelium of the external auditory meatus, and may spread to involve the middle
ear.
The most important primary tumour presenting in the middle ear is a
paraganglioma. Derived from the glomus jugulare, it is a neuroendocrine tumour.
There is a female preponderance and most patients are between 40 and 60 years
old. The tumours are slow-growing and may present late, causing damage by
destruction of the ossicles and perforation of the eardrum.
In children, rhabdomyosarcoma is an important tumour of the ear. |
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