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时间:2010-07-13 11:06来源:蓝天飞行翻译 作者:admin
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history and physical examination might confirm such a finding. The term ‘vertigo’ has different meanings to
different people. To earthbound individuals it usually means dizziness. To a pilot it means, in simple terms,
disorientation, i.e. loss of frame of reference and loss of orientation in space.
Disorientation in the air is described in Part III, Chapter 9 of this manual as a condition of importance in
aviation medicine which has its basis in physiological mechanisms but which may be perpetuated by
psychological factors.
ICAO Preliminary Unedited Version — October 2008 III-12-25
In the absence of a visual reference, e.g. when flying in clouds or darkness without instruments, the vestibular
information can be confusing or misleading. Distortion of the hair cells in the vestibular system sets up a chain
of reflexes which produce postural, proprioceptive and oculomotor responses. Thus the examiner's interest lies
in such important reactions as nystagmus, past pointing, and falling.
A pilot with spatial disorientation (SD) has an incorrect mental impression of the position, attitude and
movement of the aircraft; SD during flight can have fatal consequences. Many pilots have had episodes of
disorientation in various environments. They may accept these as normal or believe them to be symptoms of
abnormality in themselves or in their aircraft. Whether they report disorientation, even under direct
questioning, is influenced by:
a) their recognition that they were disoriented;
b) their ability to assess potential dangers in such episodes and their willingness to report them;
c) social and economic pressures:
1) will their admission have desired consequences, e.g. a medical excuse to give up a no longer
desired career?
2) will their admission have undesired consequences, e.g. groundings, loss of pay, status, career?
d) their confidence (or lack of it) in those to whom they might turn for help, e.g. their medical examiner.
HISTORY
The most important consideration is to determine whether the pilot actually had experienced true vertigo (a
sensation of turning or spinning of oneself or one's surroundings) or merely a feeling of tridimensional
instability, giddiness, light-headedness or faintness. The time spent in clarifying this point is wisely invested.
When no true vertigo is present, the aetiology must be sought somewhere other than in the vestibular
apparatus.
Disorientation may be related to many flight conditions. One of these is rapid changes in altitude, which may
produce pressure-induced vertigo, mainly during descent due to blockage and clearing of the middle ear. Pilots
who experience this condition repeatedly or severely should be referred to an experienced aviation ENT
specialist, who is able to determine whether it is a case of simple alternobar vertigo or a perilymphatic fistula
(inner ear barotrauma). In general, pilots should be warned that disregarding the signs of a common cold and
flying with an upper respiratory infection may result in acute incapacitation caused by pain in the ears or
sinuses and, in some cases, an additional non-reversible vertigo and hearing loss which may lead to permanent
grounding.
Occurrence of vertigo in circumstances other than flight or the persistence of a particular pattern of
disorientation (such as spinning or tilting, or position dependent vertigo) suggests labyrinthine disease.
Vestibular neuronitis (and acute labyrinthitis), Menière's disease12, benign paroxysmal position nystagmus
and other miscellaneous causes of vertigo, should be taken into account and applicants assessed accordingly.
12 Menière’s disease: an affection characterised clinically by vertigo, nausea, vomiting, tinnitus, and fluctuating and
progressive sensory hearing loss associated with endolymphatic hydrops. After Prosper Menière, French physician
(1799-1862).
ICAO Preliminary Unedited Version — October 2008 III-12-26
PHYSICAL EXAMINATION
The physical examination, as outlined earlier in this manual, must be carefully done and recorded for each
pilot having a history of vertigo. The examiner should have the results of the cardiopulmonary evaluation;
blood pressure determinations may lead to a diagnosis of orthostatic hypotension as the cause of dizziness.
Hearing loss accompanying vertigo is often associated with localized labyrinthine disease. In patients with
true vertigo and perceptive hearing loss, two sites of involvement must be suspected: the end organ and the
eighth cranial nerve. Audiometry is the more satisfactory method of localizing the lesion. Pure-tone
audiometry, while able to distinguish conductive and sensorineural hearing losses, will not aid in this
localization. End organ disease is indicated by the presence of recruitment. Eighth nerve disease is indicated
 
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