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AETIOLOGY. Chronic suppuration of the middle ear results from infection of
the mucosal lining of the middle ear cleft and in the vast majority' of cases
is preceded by an acute suppuration which has been untreated or inade-
quately treated. The expected decrease in incidence following the introduc-
tion of antibiotic therapy for acute infections has not been fully realized
and it remains a common disorder in otological clinics. Sociologically it
is more common in poorer sections of the population amongst whom
hygienic, housing and dietetic factors may be contributory. In some cases
of tubotympanic disease upper respiratory tract infection is an important
cause of continued otorrhoea.

BACTERIOLOGY. Compared with the pyogenic organisms found in acute
infections there is in chronic disease a substantial increase in Gram-negative
organisms such as B. proteus, Ps. pyocyanea and Esch. coli. Invasion of the
middle ear by these bacilli occurs by way of the external meatus and the
perforation in the drumhead.

CLINICAL FEATURES. Chronic suppurative otitis media may be seen in
varying stages, an active one where there is purulent discharge, an inactive
one when there has been no discharge or evidence of infection for 6 months
or longer and a quiescent stage of shorter duration occurring between periods
of activity. A final stage of healed otitis media is present when all signs of
activity have ceased and the perforation in the drumhead, which is the
portal for reinfection, has healed.

The presence of discharge may obscure the tympanic membrane in which
case the meatus should be cleared by gentle syringeing or by dry mopping
to obtain a satisfactory view. The characteristics of the perforation must be
noted. The site of the perforation is of particular importance in determining
with other factors whether the ear infection is of a dangerous type or of a
safe type. In the latter type the perforation will be situated in the central
or anterior portions of the drumhead and is associated with disease in the
tubotympanic area of the middle ear. Perforations in the attic region or
extending to the posterior margin of the membrane are associated with
disease in the attic and mastoid antrum signifying a dangerous or unsafe
ear (see Plate X, 9-14).

In a number of cases the drumhead is hidden by an aural polypus in the
external meatus. The polypus may originate from the margin of the mem-
brane or from the promontory of the medial wall of the middle ear, its
stalk passing through the perforation. Not infrequently the membrane is
partially obscured by granulations protruding through an attic or posterior
marginal perforation, these being more commonly associated with unsafe
ears, whereas an aural polypus may be present in either type of disease.