title: Temporal structure of variability decreases in upper extremity movements post stroke.
abstract: BACKGROUND
  The objective of this study was to determine movement variability in the more-affected upper-extremity in chronic stroke survivors. We investigated two hypotheses: (1) individuals with stroke will have increased amount of variability and altered structure of variability in upper-extremity joint movement patterns as compared to age-matched controls; and (2) the degree of motor impairment and joint kinematics will be correlated with the temporal structure of variability.
  
  
  METHODS
  Sixteen participants with chronic stroke and nine age-matched controls performed three trials of functional reach-to-grasp. The amount of variability was quantified by computing the standard deviation of shoulder, elbow, wrist and index finger flexion/extension joint angles. The temporal structure of variability was determined by calculating approximate entropy in shoulder, elbow, wrist and index finger flexion/extension joint angles.
  
  
  RESULTS
  Individuals with stroke demonstrated greater standard deviations and significantly reduced approximate entropy values as compared to controls. Furthermore, motor impairments and kinematics demonstrated moderate to strong correlations with temporal structure of variability.
  
  
  CONCLUSIONS
  Changes in the temporal structure of variability in upper-extremity joint angles suggest that movement patterns used by stroke survivors are less adaptable. This knowledge may yield additional insights into the impaired motor system and suggest better interventions that can enhance upper-extremity movement adaptability.
authors: Department of Occupational Therapy, School of Health Professions, University of Texas Medical Branch, Galveston, TX 77555, USA. amsethi@utmb.edu
authors: Amit
authors: A
authors: Sethi
authors: Tara
authors: T
authors: Patterson
authors: Theresa
authors: T
authors: McGuirk
authors: Carolynn
authors: C
authors: Patten
authors: Lorie G
authors: LG
authors: Richards
authors: Nicholas
authors: N
authors: Stergiou
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D002908:Chronic Disease; D004551:Elbow Joint / Q000503:physiopathology; D005260:Female; D005384:Finger Joint / Q000503:physiopathology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D012785:Shoulder Joint / Q000503:physiopathology; D020521:Stroke / Q000503:physiopathology*; D014955:Wrist Joint / Q000503:physiopathology