Article

Analysis of the postural stability impairments in neurodegenerative diseases is a
very demanding task.
Age-related declines in posturographic indices are usually
superimposed on effects associated with the pathology and its treatment. We
present the results of a novel postural sway ratio (SR) analysis in patients with
Parkinson's disease (PD) and age-matched healthy subjects. The sway ratios have
been assessed based upon center of foot-pressure (CP) signals recorded in 55
parkinsonians (Hoehn and Yahr: 1-3) and 55 age-matched healthy volunteers while
standing quiet with eyes open (EO) and then with eyes closed (EC). Complementing
classical sway measure abnormalities, the SR exhibited a high discriminative
power for all controlled factors: pathology, vision, and direction of sway. Both
the anteroposterior (AP) and mediolateral (ML) sway ratios were significantly
increased in PD patients when compared to the control group. An additional SR
increase was observed in the response to eyes closure. The sway ratio changes
documented here can be attributed to a progressive decline of a postural
stability control due to pathology. In fact, a significant correlation between
the mediolateral SR under EO conditions and Motor Exam (section III) score of the
UPDRS was found. The mediolateral sway ratios computed for EO and EC conditions
significantly correlated with the CP path length (r = .87) and the mean
anteroposterior CP position within the base of support (r = .38). Both indices
reflect postural stability decline and fall tendency # in parkinsonians. The
tremor-type PD patients (N=34) showed more pronounced relationships between the
mediolateral SR and selected items from the UPDRS scale, including: falls
(Kendall Tau=.47, p < .05), rigidity (.45, p < .05), postural stability
(retropulsion) (.52), and the Motor Exam score (.73). The anteroposterior SR
correlated only with tremor (Kendal Tau = .77, p < .05). It seems that in force
plate posturography the SR can be recommended as a single reliable measure that
allows for a better quantitative assessment of postural stability impairments.
CI - Copyright (c) 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS