Symposium on the Role of the Vestibular Organs in Space Exploration (1970) / Chapter Skim
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THE SEMICIRCULAR CANALS AS A PRIMARY ETIOLOGICAL FACTOR IN MOTION SICKNESS
THE SEMICIRCULAR CANALS AS A PRIMARY ETIOLOGICAL FACTOR IN MOTION SICKNESS
Pages 69-82
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From page 69... ...
The fact that typical symptoms of motion sickness (M IIA endpoint) were produced by bithermal irrigation as well as simple angular acceleration in several subjects representing a wide range of susceptibility adds to the evidence that the semicircular canals can act as the primary etiological factor in this malady.
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From page 70... ...
Recently it has been shown that even ordinary head movements in near weightlessness can produce motion sickness (ref.
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From page 71... ...
The chair remained stationary until the accumulative time totaled 300 seconds; this inactive phase was TABLE I -- Diagnastic Categorization of Different Levels of Severity of Acute Motion Sickness Category Pathognomonic, Major, 8 points Minor, 4 points Minimal, 2 points AQS,2 1 point 16 points Nausea syndrome Vomiting or Nausea II III ; N .1 • Skin retching.
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From page 72... ...
. Arslan argued that such accelerations which can be greatly exceeded in ordinary head movements probably do not harm the cupula (ref.
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From page 73... ...
When the rpm was reduced below this amount, there was characteristically a sudden marked increase in the subject's capacity for making head movements without evoking symptoms, as would be predicted from the results of testing at higher velocities. These findings indicated the possible influence and the limits of physiological mechanisms for adjusting to motion stress which are expressed as the individual's functional vestibular reserve (FVR)
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From page 74... ...
Immediately upon reaching the M IIA level the head movements were terminated, the subject returned to his upright position, and the chair was slowly decelerated (0.5°/sec2) to a stop.
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From page 75... ...
. With these values a measure of each individual's susceptibility, referred to as his Coriolis Sickness Susceptibility Index or CSSI, is simply calculated by multiplying the appropriate f-factor associated with the chair's test velocity and malaise criterion by the number of head movements N required to elicit the selected malaise criterion: TABLE 4.
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From page 76... ...
Susceptibility to Coriolis forces generated by active head movements in a rotating chair covered a wide range from what could be described as high (CSSI=1.9) to moderate (CSSI = 24.0)
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From page 77... ...
The next highest correlation (0.75) existed between susceptibility as measured by bithermal TABLE 5. -- Correlations Among Susceptibility as Ranked by Several Tests of Motion Sickness Upright angular acceleration without head movements, eyes closed (AAS)
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From page 78... ...
It must also be considered that the calorization technique stimulated mainly the vertical, whereas the angular acceleration stimulated mainly the lateral canals which may have had a differential influence upon susceptibility. The moderately high correlation between the eyes covered and uncovered conditions of the bithermal irrigation test indicates that visual cues generally had no appreciable effect upon the susceptibility of most subjects, but there were exceptions.
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From page 79... ...
Increased subjective warmth was experienced more frequently in the Coriolis test which required active head and body movements and thereby may have contributed to the manifestation of this symptom; this test provoked increased salivation in only one subject. Cold sweating was conspicuously absent in the offvertical rotation and the angular acceleration tests which, on the other hand, featured increased salivation.
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From page 80... ...
The ideal pattern of response is illustrated by cases D and E As a rule, when a subject experienced M IIA and M III with only a few head movements (cases A, B, C)
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From page 81... ...
resulted. In these studies the intensity and duration of the vestibular stimulus were individually controlled so as to provide an equivalent stressor stimulus in terms of the response of each subject under each test condition as diagnosed by specific criteria (ref.
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From page 82... ...
KENNEDY, R S.; AND GRAYBIEL, A.: The Dial Test: A Standardized Procedure for the Experimental Production of Canal Sickness Symptomatology in a Rotating Environment.
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