THE EXTERNAL ACOUSTIC MEATUS 299
present, and which has become very offensive and bloodstained. It is useless
to attempt to syringe them out as they are firmly attached to the meatal
walls. Chloroform water or vapour must be applied to the external meatus
in order to anaesthetize or kill the maggots and so release their grip on the
skin. Thereafter they may be removed by syringeing.
TUMOURS OF THE EXTERNAL MEATUS
Osteoma is the most common type of benign tumour encountered in the
meatus occurring either as multiple exostoses composed of ivory bone or
as a single osteoma of cancellous structure. The exostoses vary in size, and
arise from the walls of the osseous meatus as rounded swellings, or as a flat
area of thickening of part of the meatal wall to which the term hyperostosis
AETIOLOGY. The repeated entry of cold water into the external meatus in
swimming and diving is regarded as the primary cause of the condition, but
other factors such as trauma, long-standing irritation as in otitis externa or
prolonged middle ear suppuration may be contributory.
Osteomata are slow growing, often occurring in both ears, and are more
common in men than in women.
CLINICAL FEATURES. A single cancellous osteoma or exostosis is less common
than the multiple variety. It is usually attached to the posterior wall of the
osseous meatus by a narrow base and appears as a smooth rounded body
which may completely fill the canal. Multiple exostoses are frequently bi-
lateral and symmetrical, arising from the anterior and posterior osseous
meatal walls. The drumhead may be almost hidden by the growths but com-
plete blockage of the canal is unusual in this variety.
SYMPTOMS. Multiple exostoses seldom cause symptoms unless the lumen
of the meatus is obstructed by accumulation of wax or epithelial debris,
when the patient complains of deafness. In cases of otitis media pain may
occur if there is obstruction to discharge from the middle ear or if there is a
secondary otitis externa.
DIAGNOSIS. The diagnosis is generally clear on inspection although wax
and debris may first require to be removed in order to view the growth. Its
bony consistence is confirmed by touching it with a probe.
TREATMENT. Multiple osteomata which are not giving rise to symptoms
require no treatment, and when they are observed only as part of a routine
examination their presence is best left unremarked to the patient. These
growths are very hard and the visible part may resemble the tip of the ice-
berg. The larger submerged portion of a growth arising from the posterior
meatal wall may be closely related to the facial nerve canal so that removal
may cause damage to the facial nerve. When removal is necessary on account
of persistent symptoms it is best effected by the use of a high-speed drill and
suitable burrs applied directly to the growths via the external meatus, which
is widened if necessary by an endaural incision.
Surgery is more often necessary in the case of single cancellous osteoma
which is likely, by its continued and more rapid growth, to cause complete
obstruction of the meatus. Because of its pedunculated attachment this
type of osteoma may frequently be removed by applying a gouge to the
pedicle of the growth and cracking it at its base. Care must be taken to