Congenital
anomalies
Congenital anomalies of the middle ear may be isolated or may be associated with other ear or general congenital deformities. There is a number of branchial arch syndromes — for example Pierre Robin’s syndrome, craniofacial dysostosis, Down’s syndrome and Treacher Collins’ syndrome. If there is an external ear abnormality, it should raise suspicion of an underlying middle ear deformity. Middle ear deformity can be assessed by high-resolution computerised tomography (CT) scanning and, if the inner ear is normal, reconstructive surgery of the middle ear can be very successful.
Trauma
Trauma to the middle ear can result in a
perforated tympanic membrane (Fig. 40.9a). Such perforations usually heal
spontaneously
(Fig. 40.9b). Trauma can result is ossicular
discontinuity and typically it is
the incus that is displaced. Various operations termed ‘tympanoplasties’ are
available to reconstruct the damaged ossicular chain and repair the tympanic
membrane if necessary.
Inflammatory
disorders
The most common inflammatory condition of the
middle ear is acute suppurative otitis media. It is extremely common in
childhood and is characterised by purulent fluid in the middle ear. Mastoiditis
may be associated with otitis media because the mastoid air cells connect freely
with the middle ear space. The tympanic membrane is hyperemic and bulges owing
to pressure from the pus in the middle ear (Fig.
40.10). The child suffers
extreme pain until the tympanic membrane bursts. The most common infecting
organisms are Streptococcus pneumoniae and
Haemophilus influenzae. Appropriate
systemic antibiotics should be given for 10 days.
The
incidence of acute mastoiditis has diminished with the widespread use of
antibiotics for otitis media. Sometimes, however, a child will have had a number
of courses of antibiotics, none of which completely resolves the middle ear
infection. In such cases the pain and swelling behind the ear may not be quite
so apparent as in Fig. 40.11. When mastoiditis is present, if the tympanic
membrane can be seen, there is always a sag in the posterior superior part of
the drum. (Conversely, a normal tympanic membrane excludes mastoiditis.)
Treatment requires hospital admission and
Mastoiditis
•
Sequelae of acute otitis media
•
May be masked by antibiotics
•
Requires intensive antibiotics and/or drainage
Otitis
media with effusion (glue ear) is very common with the majority of children
experiencing at least one episode of it during development. Many factors have
been implicated, although it is primarily thought to be due to poor eustachian
tube function. Oxygen is continually being absorbed by the middle ear mucosa and
this results in a negative middle ear pressure unless the eustachian tube opens
to replenish the air. This negative middle ear pressure initially results in
transudation of fluid into the middle ear space (Fig.
40.12). If the hypoxia
continues, a mucoid exudate is produced by the glands within the middle ear
mucosa. This sticky exudate is referred to as ‘glue ear’.
The
following symptoms may be associated with glue ear:
•
hearing impairment which often fluctuates;
•
delayed speech;
•
behavioral problems;
•
recurrent ear infections — this occurs because the exudate is an ideal
culture medium for microorganisms;
•
reading and learning difficulties at school.
If
these symptoms are present for a short time only, it is likely that no long-term
sequelae will develop. However, if symptoms persist, particularly a long-term
bilateral conductive hearing loss, the child will miss out on educational
opportunities and may not fulfil his or her academic potential. The otoscopic
findings of exudative glue ear are of a dull drum that is immobile on pneumatic
otoscopy (Fig. 40.13).
The tympanic membrane is retracted and radial
blood vessels may be present (Fig. 40.14). Of children first presenting with
bilateral glue ear, 50 per cent of the effusions will resolve spontaneously
within 6 weeks of onset. Initially, a ‘wait and watch’ policy is therefore
appropriate. If the bilateral glue ear persists with a significant hearing loss
then treatment is required.
There
is no substantial evidence for medical treatment. Use of the Otovent device (Fig.
40.15) may improve eustachian tube function and is worth trying while
waiting for resolution of the effusion. However, surgical intervention is the
only effective way of curing glue ear. Both ventilation tube (groin-mets) and
adenoidectomy are effective. The controversy is not whether surgery works but
when to intervene.
Otitis media with effusion (glue ear)
•
Very common, peaks at 18 months and 5 years
•
Majority of children need no treatment
•
Prolonged hearing loss treated with ventilation tubes and/or
adenoidectomy
A
middle effusion in adults is relatively rare and when it occurs does not usually
last long. The condition is often associated with an upper respiratory tract
infection. A persistent unilateral effusion in an adult should always be
viewed with suspicion. A nasopharangeal carcinoma may cause the effusion by
blocking the opening of the eustachian tube in the
Chronic suppurative otitis media
Chronic suppurative otitis media (CSOM) is
classified into two types: tubotympanic disease, in which there is a perforation
of the pars tensa; and atticoantral disease, in which a retraction pocket
develops from the pars flaccida.
CSOM
of the tubotympanic type. CSOM of the tubotympanic type can result from trauma
or infection. When perforated the tympanic membrane usually repairs itself, but
occasionally the outer layer of the tympanic membrane fuses with inner mucosa
and a chronic perforation results (Fig. 40.17). With this type of disease the
patient’s main symptoms are of an intermittent or chronic mucoid discharge
associated with a mild conductive hearing loss. It is rare for this type of
disease to be associated with intracranial complications.
A
diagnosis is made on otoscopy and the tuning forks usually suggest a conductive
hearing impairment. The first-line treatment is topical antibiotic and steroid
drops, and on occasion microsuction. If medical treatment fails, the patient may
request an operation to graft the tympanic membrane in order to give a dry ear.
This operation is termed a myringoplasty (type I tympanoplasty). The edges of
the perforation are freshened and a small piece of temporalis fascia is inserted
under the tympanic membrane to graft the drum. The raw epithelial edges then
grow across the graft to repair the tympanic membrane.
CSOM
of the atticotympanic type. CSOM of the atticoantral type is important because
of the complications associated with it. Cholesteatoma is the
alternative name and means a cyst or sac of squamous epithelium that is present
in the attic part of the middle ear. The exact aetiology of cholesteatoma is not
known, although poor eustachian tube function is implicated (e.g. patients with
cleft palates have relatively poor eustachian tube function and have a higher
incidence of cholesteatoma).
A
retraction pocket develops in the pars flaccida and, if the squamous epithelium
cannot migrate out of this pocket, a cholesteatoma results. The expanding ball
of skin causes a low-grade osteomyelitis which results in the release of fatty
acids from the bone. This gives the discharge its characteristic faecal smell.
Invariably the discharge is accompanied by hearing loss and mild discomfort. The
patient may simply put up with the symptoms until a severe complication occurs.
The
hearing loss that is caused by cholesteatoma may be conductive due to erosion of
the incus or sensori neural due to direct erosion of the cochlea or migrations of
toxins into the inner ear. Vestibular symptoms may occur because of erosion of
the semicircular canals or the migration of toxins into the vestibule. Pressure
or erosion of the facial nerve is relatively unusual.
The
close proximity of the middle ear and mastoid to the middle and posterior
cranial fossae means that intracranial
sepsis can result from chronic ear disease.
The infection spreads to the dura via emissary veins which connect the middle
ear mucosa to the dura or by direct extension of the disease through the bone.
Meningitis, extradural, subdural or intracerebral abscess, or a combination of
these may occur. The main causes of intracranial sepsis in the UK are chronic
ear disease and chronic sinus disease.
Diagnosis
should be suspected on otoscopy (Fig. 40.18). Pus, crusts, granulations or a
whitish debris in the attic are hallmarks of the disease. Examination under the
microscope, audiometry and, sometimes, CT scanning are indicated.
The
treatment is surgical and follows the principle of exposing the disease,
excising the disease and then exteriorising the affected area. Two commonly
applied operations for this disease are an atticotomy and a modified radical
mastoidectomy.
An
atticotomy or modified radical mastoidectomy is performed by making an
incision behind the ear (post auricular), or between the tragus and the pinna (end aural).
The attic part of the bony ear can is drilled away and the retraction pocket is
followed back into the mastoid until the end of the disease is found. An attempt
is made to excise totally the pocket and then the resulting cavity is usually
lined with temporalis fascia. A mastoid cavity heals with normal skin that does
not migrate, and for this reason patients with a mastoid cavity need to be seen
in an out-patients’ clinic on a regular basis. Any skin that collects in the
mastoid cavity needs to be removed with the aid of a sucker and a microscope (Fig.
40.19).
Chronic suppurative otitis media (CSOM)
•
In tubotympanic CSOM there is a perforated tympanic membrane and
frequently a mucoid discharge
•
Atticoantral CSOM:
— Is skin in an attic
retraction? = cholesteatoma Presents with hearing loss and smelly discharge
— Is a common cause of
intracranial sepsis
Tuberculous
otitis media is an important cause of suppuration in some countries. The
diagnosis should always be considered in any ear which fails to respond to
standard therapy. A swab for appropriate culture studies, coupled with chest
radiography, will usually confirm the diagnosis.
Otosclerosis
is a condition in which new abnormal spongy bone is laid down in the dense otic
capsule. Of particular importance is the bone that is laid down around the
footplate of the stapes which impedes the mobility of the stapes and results in
a conductive hearing loss (Fig. 40.20). Toxins released from the new bone
formation may also cause a gradual sensorineural hearing loss. Otosclerosis is
more common in women, and in 50 per cent of patients there is a family history.
The typical presentation is of a conductive hearing loss in a young woman with
the condition being exacerbated by the hormonal flux of pregnancy. A similar
type of
The
treatment options are simple reassurance, a hearing aid or a stapedotomy
operation. In the stapedotomy operation, the stapes crura are removed and a
small hole is drilled in the fixed stapes footplate. A vein graft is then
inserted over the hole and a piston linking the incus to the vein graft is
delicately placed in position (Fig. 40.21). In 90 per cent of cases the
operation is highly successful, but rare complications include severe
sensorineural hearing loss and balance disturbance.
Otosclerosis
•
New bone formation in otic capsule
•
Stapes fixation
•
Options:
— Reassurance;
— Hearing aid;
— Stapedotomy
Neoplasms
Neoplasms of the middle ear are rare, the most
common being a glomus tumour (Fig. 40.22). Glomus tumours arise from
nonchromaffin paraganglionic tissue. The carotid body tumour arising in the neck
is an example of this type of tumour. In the temporal bone three types of glomus
tumour are recognised and classification depends on the location:
glomus tympanicum (arising in the middle ear),
glomus jugularae (arising next to the jugular bulb) and glomus vagali (skull
base).
Pulsatile
tinnitus is a classic symptom of these tumours. Hearing loss occurs and may be
either conductive or sensorineural, and paralysis of the VIIth, IXth,
Xth, XIth and/or XIIth nerves may occur. The classic sign is a cherry-red mass
lying behind the tympanic membrane. An audible bruit may be heard with a
stethoscope over the temporal bone. The treatment of choice is preoperative
einbolisation followed by surgical excision. Radiotherapy is also effective.
Squamous
cell carcinoma may also occur within the middle ear. It usually presents with
deep seated pain and a bloodstained discharge. The facial nerve may be
paralysed. Squamous carcinomas usually arise in a chronically discharging ear
and can certainly arise in a chronically infected mastoid cavity. Radical
surgical excision with or without radiotherapy provides the only chance of cure.