Article

Cerebrovascular accident (stroke) often results in impaired motor control and
persistent weakness that may lead to chronic disability, including deficits in
gait and balance function. Finding ways to restore motor control may help reduce
these deficits; however, little is known regarding the capacity or temporal
profile of short-term motor adaptations and learning at the hemiparetic ankle.
Our objective was to determine the short-term effects of a single session of
impedance-controlled ankle robot ("anklebot") training on paretic ankle motor
control in chronic stroke. This was a double-arm pilot study on a convenience
sample of participants with chronic stroke (n = 7) who had residual hemiparetic
deficits and an equal number of age- and sex-matched nondisabled control
subjects. Training consisted of participants in each group playing a target-based
video game with the anklebot for an hour, for a total of 560 movement repetitions
in dorsiflexion/plantar flexion ranges followed by retest 48 hours later. Task
difficulty was adjusted to ankle range of motion, with robotic assistance
decreased incrementally across training. Assessments included robotic measures of
ankle motor control on unassisted trials before and after training and at 48
hours after training. Following exposure to the task, subjects with stroke
improved paretic ankle motor control across a single training session as indexed
by increased targeting accuracy (21.6 +/- 8.0 to 31.4 +/- 4.8, p = 0.05), higher
angular speeds (mean: 4.7 +/- 1.5 degrees/s to 6.5 +/- 2.6 degrees/s, p < 0.01,
peak: 42.8 +/- 9.0 degrees/s to 45.6 +/- 9.4 degrees/s, p = 0.03), and smoother
movements (normalized jerk: 654.1 +/- 103.3 s(-2) to 537.6 +/- 86.7 s(-2), p <
0.005, number of speed peaks: 27.1 +/- 5.8 to 23.7 +/- 4.1, p < 0.01). In
contrast, nondisabled subjects did not make statistically significant gains in
any metric after training except in the number of successful passages (32.3 +/-
7.5 to 36.5 +/- 6.4, p = 0.006). Gains in all five motor control metrics were
retained (p > 0.05) at 48 hours in both groups. Robust maintenance of motor
adaptation in the robot-trained paretic ankle over 48 hours may be indicative of
short-term motor learning. Our initial results suggest that the anklebot may be a
flexible motor learning platform with the potential to detect rapid changes in
ankle motor performance poststroke.

Langue : ANGLAIS