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Mechanics of Coriolis stimulus and inducing factors of motion sickness.

To specify inducing factors of motion sickness comprised in Coriolis stimulus, or cross-coupled rotation, the sensation of rotation derived from the semicircular canal system during and after Coriolis stimulus under a variety of stimulus conditions, was estimated by an approach from mechanics with giving minimal hypotheses and simplifications on the semicircular canal system and the sensory nervous system. By solving an equation of motion of the endolymph during Coriolis stimulus, rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then the sensation derived from the whole semicircular canal system was particularly considered in two cases of a single Coriolis stimulus and cyclic Coriolis stimuli. The magnitude and the direction of sensation of rotation were shown to depend on an angular velocity of body rotation and a rotating angle of head movement (amplitude of head oscillation when cyclic Coriolis stimuli) irrespective of initial angle (center angle) of the head relative to the vertical axis. The present mechanical analysis of Coriolis stimulus led a suggestion that the severity of nausea evoked by Coriolis stimulus is proportional to the effective value of the sensation of rotation caused by the Coriolis stimulus.

Acceleration↗

Behavioral methods of alleviating motion sickness: effectiveness of controlled breathing and a music audiotape.

BACKGROUND: Behavioral countermeasures for motion sickness would be advantageous because of the side effects of antiemetic drugs, but few alternative treatments are available. The objective of this study was to compare the effectiveness of controlling breathing and listening to a music audiotape designed to reduce motion sickness symptoms, on increasing tolerance to motion-induced nausea. METHOD: Twenty-four healthy subjects were exposed to nauseogenic Coriolis stimulation on a rotating turntable under three conditions: whilst focusing on controlling breathing; listening to a music audiotape; or without intervention (control). The three conditions were performed by each subject according to a replicated factorial design at 1-week intervals at the same time of day. Ratings of motion sickness were obtained every 30 seconds. Once a level of mild nausea was reached subjects commenced controlling breathing or listened to the music audiotape. Motion was stopped after the onset of moderate nausea. RESULTS: Mean (+/- SD) motion exposure time in minutes tolerated before the onset of moderate nausea was significantly longer (p <.01) for controlling breathing (10.7 +/- 5.6 min) and longer (p <.01) for music (10.4 +/- 5.6 min) compared with control (9.2 +/- 5.9 min). CONCLUSIONS: Both controlling breathing and the music audiotape provided significant protection against motion sickness and with similar effectiveness. These nonpharmacologic countermeasures are only half as effective as standard doses of anti-motion sickness drugs, such as oral scopolamine; however, they are easy to implement and free of side effects.

Adult↗

Sodium concentration in saliva along the time course of experimental Coriolis sickness.

Procedures designed to evaluate the severity of motion sickness have included subjective reporting of changes in salivation. In order to increase objectivity, we studied the sodium concentration of saliva, which is directly related to the flow rate. Healthy adults with normal vestibular function underwent a modified Coriolis Sickness Susceptibility Index (CSSI) test, utilizing a staircase profile. Saliva was collected without interrupting the stimulus by means of cotton placed beneath the subject's tongue for one minute. Samples were obtained 5 min prior to stimulation, 30 and 45 min following stimulus onset, and/or upon reaching the "nausea II" endpoint. Saliva for analysis by atomic absorption spectrophotometry was obtained by centrifugation of the cotton. A significant difference in sodium concentration was found between the baseline and 30-min sample (p less than 0.01). Although the amount of salivation was rather variable, the pattern of changes in sodium concentration was similar in all experimental cases.

Adult↗

Salivary total protein and experimental Coriolis sickness.

Symptomatic reporting has been used in quantifying the severity of motion sickness including Coriolis sickness. This study was designed to objectively examine if the dynamic changes of salivary protein concentration relate to the severity of Coriolis sickness. Healthy adults with normal vestibular function underwent a modified Coriolis Sickness Susceptibility Index (CSSI) test, utilizing a staircase profile. Salivary samples were obtained prior to stimulation, 15, 30, and 45 min following stimulus onset, and/or upon reaching "nausea-II" endpoint. Total protein concentration tended to rise over the initial 30 min of stimulation, and then level off or decline. A statistically significant difference was found between the pre-stimulation and 30 min samples. Although some variability existed among the subjects, the general pattern of changes along the time course was similar. An inverse correlation approaching statistical significance was found between control (non-stimulus) total protein levels, and minutes of Coriolis stimulation required to reach the "nausea-II" endpoint. Thus, baseline salivary total protein levels can be of use in predicting susceptibility of Coriolis sickness and other forms of motion sickness.

Adult↗

Vision and motion sickness.

The development of motion sickness appears intimately related to the visual system. The Sensory Rearrangement Theory states that situations which promote motion sickness are characterized by a condition in which the motion signals transmitted by the eyes, vestibular system, and the nonvestibular proprioceptors are at variance as to what was expected previously. The evolutionary significance of motion sickness rests in its linkage to an early warning system to avoid poisoning. Vision is capable of aiding in the development of suppression of motion sickness. Therapy of motion sickness includes posture, restriction of head movement, visual manipulations, concurrent activity, drugs, and adaptation.

Animals↗

[Benign paroxysmal positional vertigo].

Benign paroxysmal positional vertigo is a common malfunction of the labyrinth, most frequently of the posterior canal, due to clot of debris in the endolymph. The attacks of vertigo are characterised by dependency on position, latency after positioning of the head, short duration, nystagmus, reversibility and fatiguableness. The diagnosis can be based on history, physical examination and provocative tilting of the head as described by Dix and Hallpike. In a typical case further investigations are not necessary. The symptoms often improve spontaneously. Half of the patients can be cured directly by stepwise tilting. This probably removes the clot from the canal of the labyrinth to the utriculus. Specific positional exercises also often have a good result, but not as quickly. Drug therapy has no place in the treatment.

Cerebellar Diseases↗

[An experimental validation of pharmacological agents to arrest the vestibulo-autonomic syndrome (motion sickness)].

The results of development and experimental evaluation of the efficiency of pharmacological means of cupping the vestibulo-vegetative syndrome in man are presented. A model and procedure of evaluation of pharmacological cupping of the Vestibulo-vegetative syndrome are developed. The intramuscular injection of the mixture containing ephedrine, promethazine hydrochloride and strychnine (25, 50, and 1 mg, respectively) appeared most effective.

Coriolis Force↗

[Effect of an increased content of oxygen and carbon dioxide on vestibular resistance].

Forty-two experiments on 21 test subjects, aged 20 to 40, were carried out to study possibilities of increasing vestibular resistance. This was achieved by improving the cerebral blood supply of the subjects who used the breathing air of 40-43% oxygen, 2% carbon dioxide and nitrogen. The results were treated statistically. This breathing air proved to increase the resistance of the vestibular analyzer to adequate stimuli. It is recommended to use this breathing air consisting of 40-43% oxygen, 2% carbon dioxide and nitrogen to prevent motion sickness and to discontinue vestibulo-vegetative disturbances that may appear in people using different flying and ground vehicles.

Adult↗