Article

Light touch with a stable object reduces postural sway by increasing
axial postural tone in healthy subjects. However, it is unknown whether subjects
with Parkinson's disease (PD), who have more postural sway and higher axial
postural tone than healthy subjects, can benefit from haptic touch. OBJECTIVE: To
investigate the effect of light and heavy touch on postural stability and hip
tone in subjects with PD. METHODS: Fourteen subjects with mid-stage PD and 14
healthy control subjects were evaluated during quiet standing with eyes closed
with their arms (a) crossed, (b) lightly touching a fixed rigid bar in front of
them, and (c) firmly gripping the bar. Postural sway was measured with a
forceplate, and axial hip tone was quantified using a unique device that measures
the resistance of the hips to yaw rotation while maintaining active stance.
RESULTS: Subjects with PD significantly decreased their postural sway with light
or heavy touch (P < .001 vs arms crossed), similarly as control subjects. Without
touch, hip tone was larger in PD subjects. With touch, however, tone values were
similar in both groups. This change in hip tone with touch was highly correlated
with the initial amount of tone (PD, r = -.72 to -.95; controls, r = -.74 to
-.85). CONCLUSIONS: The authors showed, for the first time, that subjects with PD
benefit from touch similarly to control subjects and that despite higher axial
postural tone, PD subjects are able to modulate their tone with touch. Future
studies should investigate the complex relationship between touch and postural
tone.

Langue : ANGLAIS