Trial-By-Trial Variation In Upper Extremity Movement Smoothness After Acute Stroke Relates To Clinical Assessments And Corticospinal Tract Injury.
Sarah K Cavanagh, Perman Gochyyev, Rashida Nayeem and 8 others
PMID 40448525WHAT IT FOUND
After acute stroke, trial-by-trial variation in arm movement smoothness predicts 90-day recovery and fine motor skills better than average smoothness.
This variability correlates with corticospinal tract injury, suggesting it reflects noisy signal transmission rather than just weakness.
Key findings
01Trial-by-trial variation in movement smoothness (IQR) was significantly associated with acute fine motor assessments (9-Hole Peg and Box and Blocks) even after controlling for average smoothness.
02Acute movement smoothness variability independently predicted 90-day outcomes for fine motor skills, upper extremity impairment, and global disability.
03Greater injury to the corticospinal tract was associated with both less smooth movements and higher trial-by-trial variation in smoothness.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
Small sample size (22 patients) limits generalizability. Control group was significantly younger than the stroke group. Participants performed the task only once, so test-retest reliability of these kinematic measures is unknown. The study used a specific 2D planar reaching task, which may not reflect naturalistic 3D functional movements. The robotic device used (InMotion2) is not commonly available in all clinical settings, and cost/training are barriers to adoption.
Declared interests
Not reported in the provided text.
The easy way to misread this
Do not interpret this as evidence that robotic assessment is currently practical for routine clinical use. The study used a specialized research robot, and the authors explicitly note that cost, time, and training associated with such devices are significant barriers to clinical utility.