Analysis of stability of human upright posture based upon the measurement of the head sway.

The paper is dealing with the description of a simple and inexpensive technique for recording and measuring of the head sway during upright stance. In particular the recording system and the evaluation of the body sway data are highlighted. The objectives of the head sway signal analysis are the determination of sway components in the side-to-side (lateral) direction and forward-backward (anteroposterior) direction. It is anticipated that it will be possible to extract from the digitized data some information about the transfer characteristic and stability margin of the neuromuscular control system concerned with the maintenance of equilibrium. Additional information of potential clinical significance could be obtained by correlating the measured sway data with electromyographically determined changes in the activity of the main postural muscles. The information obtained is comparable to that gathered by more sophisticated, and more expensive conventional devices. A special feature is the easy portability of the system which permits collection of stabilometric data even in remote locations, while the analysis on which the diagnostic assessment is based can be performed at a later date in a central facility equipped with the necessary instrumentation.