Balance in Parkinson's disease under static and dynamic conditions

We tested balance performance in 15 on phase
Parkinson’s disease (PD) patients (8 nonfallers, PD-NF; 7
fallers, PD-F) during quiet stance (stabilometry) and on a
platform continuously moving in the anteroposterior direction
(dynamic test). Neither stabilometry (eyes open or closed) nor
the dynamic test (eyes open) separated PD-F from PD-NF.
With the dynamic test, eyes closed, PD-F with respect to
PD-NF showed larger head oscillations, smaller cross-correlation
between head and malleolus motion (more so in patients
with low Unified Parkinson’s Disease Rating Scale, or UPDRS),
and larger delays of head with respect to platform
motion. Further, across all PD patients, head displacement
increased with the equivalent levodopa dose, indicating a trend
for medication to worsen balancing capacity while improving
UPDRS. The dynamic test is a sensitive tool for detecting
instability in PD-F since absence of visual flow selectively
impairs both association between body segment movements
and anticipatory adjustments.