Examination of the vestibular system by short-time accelerations

Short accelerations, lasting for the split part of a second can be produced by the chair rotating with uniform speed in such a way that the chair will change its direction after each turn of 360 degrees. The accelerations of alternating directions produce ampullopetal flows in the right and the left labyrinth alternately. The nystagmus elicited will be finished during the rotation of the chair with uniform speed, thus during the stimulus-free period. The short acceleration rates render possible the multiple dosage of identical stimuli as well as the gradual increase of the intensity of the stimulus. Since the stimulus produces ampullopetal flow in the right and the left labyrinth alternately the central vestibular equilibrium will not be changed. The author applied acceleration stimuli of 20, 30, 40 and 50 degrees/sec2 doses to 20 healthy male subjects and studied the manifestations of the nystagmus elicited.