Motion sickness and space sickness: clinical and experimental findings.

Vertigo in motion sickness forms a clear clinical picture. We can confirm that complex symptoms are due to abnormal stimulations of labyrinth receptors subsequent to simultaneous multi-plane angular accelerations. This labyrinth stimulation originates from Coriolis' complementary accelerations. The seriousness of kinetosis symptoms can vary according to different causes; level of labyrinth stimulation, subject's constitution, psychological and physical conditions and whether or not the subject is accustomed to kinetic stimulations. Space sickness shows similar symptoms and similar psychological mechanisms. Recent space experiences have shown that disturbances due to acceleration sickness vary according to labyrinth receptor adaptability to kinetic stimulations in space. In a clinical and experimental study, we investigated the importance of the spacial plane, in which the head movement occurs, in causing the greatest reactions due to Coriolis' complementary accelerations in man. A close relationship between nystagmic responses and the level of endolymphatic shifting in each canal was observed and studied with the help of mathematical models.