The Importance of Head Movements in Studies Involving Stimulation of the Organ of Balance

Abstract

SUMMARY AND CONCLUSIONS

Certain findings and procedures have been described which enable precise determinations of the sensitivity of the various components of the non-auditory membranous labyrinth.

We wish to emphasize very strongly one point which applies to motion sickness induced by various devices. The angular and linear accelerations that have been described as characteristic of various pieces of apparatus refer to the apparatus alone. If valid conclusions on the effects of these accelerations are to be drawn, care must be taken to ensure that the motion of the subject's head conforms as closely as possible to that of the apparatus. If the head is allowed to move freely, either voluntarily or involuntarily, it will be subject to additional accelerations due to these motions, and, in particular, to angular accelerations because of the short radii involved in head movement with respect to the body (rotation of the head in the horizontal plane or swinging anteroposteriorly or laterally on the neck).

It is hoped that the procedure outlined will be of use to those interested in vestibular threshold determinations both from the point of view of basic physiology and in the diagnosis of vestibular disease.