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Trial-By-Trial Variation In Upper Extremity Movement Smoothness After Acute Stroke Relates To Clinical Assessments
Sarah K Cavanagh1,2,3, Perman Gochyyev4, Rashida Nayeem5
1John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
Neurorehabilitation and Neural Repair
|May 31, 2025
Summary
Movement variability after stroke significantly impacts upper extremity function. Higher trial-by-trial variation in movement smoothness, even with average smoothness controlled, correlates with poorer clinical outcomes and greater corticospinal tract injury.
Area of Science:
- Neurology
- Movement Science
- Rehabilitation Medicine
Background:
- Stroke impairs motor control, leading to reduced upper extremity movement smoothness and increased variability.
- Characterizing trial-by-trial movement variation and its clinical correlates in acute stroke is crucial for understanding recovery.
- Previous research has limited focus on the immediate post-stroke period for movement variability.
Purpose of the Study:
- To assess trial-by-trial variation in upper extremity movement smoothness during reaching tasks in acute stroke patients.
- To investigate the relationship between movement smoothness variability and clinical outcomes and neuroanatomical injury.
Main Methods:
- Twenty-two acute stroke patients and 22 controls performed a planar reaching task.
- Movement smoothness quantified using spectral arc length (SPARC); trial-by-trial variation assessed via interquartile range (IQR).
- Clinical assessments and MRI-derived lesion data (basal ganglia, motor cortex, corticospinal tract) were analyzed.
Main Results:
- Stroke patients exhibited less smooth and more variable reaching movements compared to controls.
- Increased smoothness variability, independent of average smoothness, correlated with worse clinical performance and 90-day outcomes.
- Higher movement variability was associated with greater corticospinal tract injury, but not basal ganglia or motor cortex lesions.
Conclusions:
- Trial-by-trial variation in movement smoothness is a significant indicator of sensorimotor control deficits post-stroke.
- Movement variability offers valuable insights for developing targeted neurorehabilitation strategies.
- Corticospinal tract integrity is linked to movement smoothness variability in acute stroke.
