Postural stability of normal subjects measured by sway magnetometry: pathlength and area for the age range 15 to 64...

Fifty-eight subjects with no known vestibular pathology, postural problems or cerebrovascular disease were studied to determine the range of sway values in a normal working-age population. Sway was measured with a magnetometry system, previously shown to be highly successful in distinguishing sway with and without the eyes open in individual subjects. 30 subjects were aged 15-29 years and 28 aged 30-64 years. With the subject standing on a firm base the pathlength and area enclosed by movement of the hips in the horizontal plane were measured over 30 second periods with eyes open and eyes closed. There were no significant differences between the two age ranges. We obtained the following upper limits of normal values for the age range 15 to 64 years: pathlength with eyes open 140 mm, pathlength with eyes closed 200 mm, area with eyes open 150 mm2, and area with eyes closed 300 mm2. The mean and standard deviation of the Romberg coefficient (sway with eyes open/sway with eyes closed) was 0.73 +/- 0.09 for pathlength measurement and 0.70 +/- 0.26 for area measurement.