Changes in postural control in healthy elderly subjects are related to vibration sensation, vision and vestibular asymmetry

The aim of this study was to analyze the composition of sway in adults and "healthy" elderly people and to evaluate the influence of vibration sensati on and asymmetric vestibular function on the sway pattern. Ten adults with a mean age of 37.5 years and 40 healthy senior citizens with a mean age of 74.6 years living independently in the community were studied. Vibration-in duced body sway was measured on a force platform. The sway was analyzed and separated into its high and low frequency components above and below 0.1 H z, respectively. Additionally the elderly subjects were observed for the oc currence of spontaneous gaze and head shake-induced nystagmus using infrare d charge-coupled device cameras and the vibration perception in the lower l imbs was tested with a tuning fork. Vibration perception was the major dete rminant for postural control in the elderly subjects. Postural control amon g the elderly subjects with intact vibration perception in their lower limb s was very similar to that of the adults. The elderly subjects with impaire d vibration sensation had increased high frequency sway compared to adults and the elderly subjects with intact sensation. Regardless of the strong in fluence of vibration sensation on postural control, asymmetric vestibular f unction might also be a contributing factor to postural instability in the elderly. Age per se had little effect on the outcome of the tests except th at the elderly subjects had diminished ability to use visual cues to reduce postural sway. We concluded that sensory status in the lower limbs is of u tmost importance for postural control in the elderly. Rehabilitation progra ms for senior citizens should therefore include exercises to preserve recog nition of body motion by the lower limbs. Exercises to facilitate vestibula r compensation could be useful for elderly people with vestibular dysfuncti on.