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chapter.
THE EXTERNAL EAR
Usually a disease of the external ear and canal, such as otitis externa or furuncles, may temporarily but will not
permanently disqualify an individual from flying. When the examiner is unable to visualize the tympanic
membrane and where the hearing is markedly impaired due to obstruction, an applicant should obtain proper
treatment and present himself later for completion of the examination.
ICAO Preliminary Unedited Version — October 2008 III-12-2
THE TYMPANIC MEMBRANE
The topography of the tympanic membrane should be well recognized. The tympanic membrane is slightly
cone-shaped, like the diaphragm of a loudspeaker. It is also slightly inclined so that the upper part is more
external or closer to the examiner's eye than the lower part. Both the concavity of the tympanic membrane and
its position relative to the auditory canal normally vary somewhat and may be greatly altered in disease.
Fig. 12-1: Normal tympanic membrane
The colour of the normal tympanic membrane is usually pearly grey. Embedded in the tympanic membrane
are the long and short processes of the malleus. The short process stands out like a tiny knob at the upper end
of the long process (or handle). The malleus is the key structure in dividing the tympanic membrane into its
four quadrants. A line drawn down through the malleus gives the anterior and posterior halves. A line drawn
perpendicular to the malleus at the level of the umbo (lower end of the malleus) gives four quadrants: anterior
superior, anterior inferior, posterior superior and posterior inferior. These are important reference areas in
reporting abnormal findings.
If the light reflex (cone of light) points to the chin, one can assume that the tympanic membrane is in a normal
position. Any retraction of the tympanic membrane will displace the cone of light inferiorly. Position-wise this
would be from 4 o'clock to 6 o'clock (right ear). Findings should be recorded in reference to the clock dial, and
by quadrants (see Figure 12-2).
ICAO Preliminary Unedited Version — October 2008 III-12-3
Fig.12-2: Right tympanic membrane – quadrants and clock numbers
Injuries of the tympanic membrane may result from suppurative disease, from direct trauma such as careless
instrumentation, or indirect injury such as from a slap on the ear or from aerotitis. The evidence of injury may
vary from slight hyperaemia to a ragged perforation of the tympanic membrane.
When examining the ears, the medical examiner should note perforations and healed perforations. Perforations
usually heal but the healed area is thinner, more transparent and also more flaccid when alternating positive
and negative pressures are produced, as with a pneumatic otoscope. Any perforations should be described as
small or large, marginal or central, and its location given by quadrant or as numbers on the clock. The type of
discharge should be described, e.g. thin, odourless, mucoid or thick, purulent with a foetid odour. Atrophic
parts of the tympanic membrane are of special concern as they may rupture when exposed to even a small
increase in differential pressure. A sudden perforation during descent may cause alternobaric vertigo and lead
to acute incapacitation. Because of their fragility, atrophic areas should be treated aeromedically as if they
were true perforations. Grey white masses of debris may be a sign of cholesteatoma which also can lead to
acute incapacitation with vertigo and/or hearing loss. Granulation tissue in the general area of the tympanic
membrane usually indicates protrusion of the tissue from the middle ear through a small perforation in the
tympanic membrane. This will often be found in the upper part of the tympanic membrane: pars flaccida or
Shrapnell's membrane1. An applicant should not be declared fit until all of these conditions have been fully
examined and evaluated.
THE MIDDLE EAR
Many conditions and diseases of the middle ear reflect their presence by alterations in the colour, position, or
integrity of the tympanic membrane.
Aerotitis media (otitic barotrauma, barotitis) is an acute or chronic pathological condition caused by the
pressure difference between the ambient air and that of the middle ear. It is characterized by fullness, deafness,
pain, tinnitus and sometimes vertigo. It is the most common otitic disorder among flying personnel today. The
1 After Henry J. Shrapnell, English anatomist (1761-1841)
ICAO Preliminary Unedited Version — October 2008 III-12-4
otoscopic findings of the aerotitis media can be classified into 5 or 6 levels according to Teed2. In the 6-level
Teed classification grade 0 is a condition with subjective symptoms but no otological signs, grade 1 diffuse
redness and retraction of the tympanic membrane, grade 2 slight haemorrhage and retraction of the tympanic
　
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本文鏈接地址：Manual of Civil Aviation Medicine 2(72)