Article

Parkinson's disease (PD) impairs the ability to shape postural responses to
contextual factors. It is unknown whether such inflexibility pertains to
compensatory steps to overcome balance perturbations. Participants were
instructed to recover balance in response to a platform translation. A step was
necessary to recover balance when the translation was large, whereas a
feet-in-place (FiP) response was sufficient when the translation was small (i.e.
no step). We compared step trials that required a switch away from the current
postural set (switch trials: step trials that were preceded by FiP trials) with
non-switch trials (i.e. step trials were preceded by identical step trials). 51
PD patients (59 +/- 7 years) were compared with 22 healthy controls (60 +/- 6
years). In a second analysis, we compared a subgroup of 14 freezers (PD-FOG) with
a subgroup of 14 non-freezers (PD-noFOG; matched for age, gender and disease
severity). Compared to non-switch trials, switch trials resulted in poorer step
execution and more steps needed to recover balance. These switching effects were
similar in PD patients and controls, and in PD-FOG and PD-noFOG patients.
Overall, PD patients demonstrated poorer stepping performance than controls.
PD-FOG had a worse performance than PD-noFOG. Moreover, PD patients, and
particularly PD-FOG patients, were less able to improve step performance with
repetitive step trials, in contrast to controls. Thus, there was no PD-related
deficit to switch to an alternative response strategy, neither in patients with
FOG nor in patients without FOG. Difficulty to adapt the step trial-by-trial
might have contributed to the absence of switch deficits in PD.
CI - Copyright (c) 2013 Elsevier B.V. All rights reserved.

Langue : ANGLAIS