CLINICAL EXAMINATION 285
While the normal appearance is readily recognized after a little practice,
the beginner experiences considerable difficulty in distinguishing many
abnormal conditions. Where difficulty exists, the short process and handle of
the malleus should be looked for in the first instance, because if they are seen
there is no doubt that the structure they lie in is the drumhead, however much
Fig. 158. Siegle's speculum.
its appearance may be altered. When they are not detected the observer must
attempt to estimate the depth of the structure at which he is looking. If it is
obviously nearer the eye than the membrane, the appearance may be due to a
polypus, granulation tissue, wax, a foreign body or some projection from the
meatal wall. If the appearances are not comparable with any condition with
which the observer is familiar, the ear should be syringed or mopped out, as
the presence of even a little pus or a flake of wax or desquamated epithelium
may be quite misleading and give rise to an incorrect diagnosis.
A minute perforation of the membrane appears as a black spot because, as
it is small, the middle ear is not lit up through it. A healed influenza! bulla
gives a somewhat similar appearance. A larger perforation allows light to
illuminate the middle ear cavity. Perforations have clear-cut edges unless they
are due to trauma in which case the edges may be ragged. A cicatrix is usually
transparent and may appear like a dry perforation (Plate X, 18), but unless it
is adherent to the medial wall of the middle ear it may be distinguished from a
perforation by means of a Siegle's pneumatic speculum (Fig. 158). This is a
speculum which expands into a small chamber and is closed at its outer end by
a lens. A small hollow tube, to which a valveless rubber ball is attached by
rubber tubing, is let into the side. The speculum is introduced into the meatus,
which it should fit closely, and an enlarged view of the drumhead is obtained.
By alternately compressing and releasing the bulb, the air in the meatus is
alternately condensed and rarefied. In the case of a cicatrix each movement of
the rubber ball makes it flap in and out (Plate X, 19) while a perforation shows
no movement, although, if the middle ear contains secretion, some discharge
may be sucked out through the perforation.