CHRONIC NON-SUPPURATIVE OTITIS MEDIA 321
may be seen through the membrane. These findings are uncommon in
Audiometry shows a conductive deafness of some 40 dB over the range
tested. The degree of deafness has some bearing in practice on the treatment
advised in that a loss of less than 25 dB may respond to removal of adenoids
alone, while a loss of 40 dB or more calls for evacuation of the fluid. Imped-
ance audiometry gives a flattened curve with displacement to the side of
negative pressure. Any coexisting high tone deafness found on audiometry
must be noted, because recovery after treatment will be confined to the
conductive element, and the child or elderly patient may still have hearing
impairment from the perceptive loss.
Mastoid radiography will show haziness of the mastoid cells from lack
of air entry, but there will be no breakdown of the intercellular walls unless
the condition is of long standing.
TREATMENT. The aim of treatment is to restore the hearing and to prevent
recurrence. A child whose symptoms have lasted for less than 6 weeks may
respond to medical treatment. Nasal decongestion is achieved by nose drops
of 1 per cent ephedrine hydrochloride in normal saline, or by giving a syrup
containing triprolidine hydrochloride and pseudoephedrine (Actifed). It has
been found that in such cases a month's course of sulphamethoxazole syrup
(Gantanol) giving 5 ml once a day is effective in about 50 per cent of patients.
Children with clinical evidence of middle ear fluid who have a conductive
deafness of less than 25 dB, and who suffer from symptoms suggestive of
adenoid enlargement, may be cured by removal of the adenoids.
The majority of patients have had a hearing loss for months when they
are first seen at hospital, and myringotomy and aspiration of the fluid are
the treatment of choice. Under general anaesthesia and with the operating
microscope wax and crusted material are removed. An incision is made in
the postero-inferior quadrant of the membrane and powerful suction is
applied. There may be considerable difficulty in aspirating all the tenacious
glue which is contained, not only in the middle ear, but also in the mastoid
antrum and cells. To facilitate this some surgeons make a second incision
of the drumhead anteriorly so that air may enter and so reduce the vacuum.
Others inject a mucolytic agent, such as chymotrypsin or urea, which
liquefies the viscid fluid. Aspiration must be continued until no more fluid
is obtained, or the chances of a recurrence are increased.
Some surgeons insert a small plastic tube, or grommet, through the
incision as a routine, while others reserve this for recurrences. The grommet
acts as a ventilating tube for the middle ear, and continues to function until
its lumen is blocked or until it is extruded. The grommet may be retained
for a few weeks or for over a year. It is momentarily painful to remove if
still in place, and in children a short anaesthetic is advisable if it becomes
necessary to remove it. Once the grommet has been extruded spontaneously
it is easily removed from the meatus in the outpatient department.
After-treatment consists in allowing no water to enter the ear. If no
grommet has been inserted the incision heals rapidly, but the parents are
advised not to allow the ear to become wet for at least a fortnight, and
swimming is forbidden for a month. If a grommet has been inserted these
restrictions obtain until it has been extruded or removed and the drumhead
has healed. Auto-inflation of the Eustachian tube is important, and the