December 20, 2017
Researchers developed a cable-driven robot to deliver perturbations to Parkinson disease (PD) patients while walking in an effort to see if participants’ compensatory responses could be strengthened and their walking balance improved.
Specifically, in the study researchers aimed to examine how PD affects individuals’ ability to walk, to respond to balance perturbations, and to produce acute short-term effects to improve compensatory reactions and gait stability.
Nine participants with idiopathic PD and 9 healthy age-matched controls were included in this study. The active-Tethered Pelvic Assist Device (A-TPAD) was developed for the study: a cable-driven robot for use in gait rehabilitation. The device is made up of a lightweight belt for across the pelvis, worn by the participant, to which multiple wires are attached. Varying degrees of forces and perturbations can be applied in any direction and at any time during the gait cycle. Thus far, the device has been successful in helping stroke survivors improve their gait.
In the experiment, participants walked on a treadmill for 5 minutes with cables attached to the brace (GAIT PRE). Participants were aware that they could be perturbed at the waist when the cables were attached, but were not informed about the magnitude, direction, or timing of the perturbations. Before the intervention started, they were instructed to try to maintain balance and keep walking.
Initially, participants were exposed to 10 posterior diagonal perturbations with peak amplitude of 15% of the body weight. Then, participants were trained with 9 blocks of 8 antero-posterior and medio-lateral perturbations of increasing intensities. Before removing the cables, all subjects were exposed to the same set of diagonal perturbations delivered before the training session. After cabled were removed, all individuals walked for another 5 minutes (GAIT POST).
Data collected during the last minute of GAIT PRE and the first and last minutes of GAIT POST were used in the analysis and were labeled as baseline, early and late post training. PD was associated with a reduced stability in the forward direction and the inability to produce proactive anticipatory adjustments (Scientific Reports. 2017; doi:10.1038/s41598-017-18075-6).
Researchers found that participants in both groups were able to improve their responses to disturbances, and short-term aftereffects of increased gait stability could be seen after cables were removed. Authors said, “A single session of perturbation-based balance training produced acute effects that ameliorated gait instability in PD.” They hope these findings will be helpful in designing subsequent interventions to remediate falls risk.—Amanda Del Signore
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