[Characteristics of motion sickness during prolonged otolith stimulation in anti-orthostatic position]

Thirty healthy volunteers were tested for an extended period of time (up to 4 hours) on modified parallel swings during a head-down tilt (-8 degrees) study. The pattern of motion sickness that developed in this situation was evaluated in terms of physiological parameters (electrocardiography, rheoencephalography, arterial pressure, respiration rate electrooculography, etc.), hormonal status, fluid-electrolyte balance, sensory function. The test subjects developed a vestibulo-hemodynamic syndrome that included vestibular disorders, spatial illusions, fluid displacement in the cranial direction, excitation of the hypothalamic-pituitary-adrenal system, changes in fluid-electrolyte balance. The resulting data may help better understand mechanisms underlying motion sickness.