Article

Many Parkinson's disease (PD) patients show asymmetries in balance control during
quiet stance and in response to perturbations (i.e., reactive balance control) in
the sagittal plane. In addition, PD patients show a reduced ability to anticipate
to self-induced disturbances, but it is not clear whether these anticipatory
responses can be asymmetric too. Furthermore, it is not known how reactive
balance control and anticipatory balance control are related in PD patients.
Therefore, we investigated whether reactive and anticipatory balance control are
asymmetric to the same extent in PD patients. 14 PD patients and 10 controls
participated. Reactive balance control (RBC) was investigated by applying
external platform and force perturbations and relating the response of the left
and right ankle torque to the body sway angle at the excited frequencies.
Anticipatory postural adjustments (APAs) were investigated by determining the
increase in the left and right ankle torque just before the subjects released a
force exerted with the hands against a force sensor. The symmetry ratio between
the contribution of the left and right ankle was used to express the asymmetry in
reactive and anticipatory balance control; the correlation between the two
ratio's was investigated with Spearman's rank correlation coefficients. PD
patients were more asymmetric in anticipatory (p=0.026) and reactive balance
control (p=0.004) compared to controls and the symmetry ratios were significantly
related (rho=0.74; p=0.003) in PD patients. These findings suggest that
asymmetric reactive balance control during bipedal stance may share a common
pathophysiology with asymmetries in the anticipation of voluntary perturbations
during, for instance, gait initiation.
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Langue : ANGLAIS