Contribution of muscle strength and integration of afferent input to postural instability in persons with stroke.
OBJECTIVE
To determine the relationship of muscle strength to postural sway in persons with stroke under standing conditions in which vision and ankle proprioception were manipulated.


METHODS
Forty persons with stroke and 40 healthy older adult controls were recruited from the community and underwent balance testing consisting of 6 conditions that manipulate vision and somatosensory information while standing. Postural sway was measured during each condition. In addition, lower extremity joint torques and cutaneous sensation from the plantar surface of the foot were assessed.


RESULTS
Postural sway was increased with more challenging standing conditions (i.e., when multiple sensory systems were manipulated) to a greater extent with the group with stroke compared to controls. Muscle strength was only correlated to sway during the most challenging conditions. Furthermore, a greater number of persons with stroke fell during the balance testing compared to controls.


CONCLUSIONS
Impairments in re-weighting/integrating afferent information, in addition to muscle weakness, appear to contribute to postural instability and falls in persons with stroke. These findings can be used by clinicians to design effective interventions for improving postural control following stroke.
Marigold
Daniel S
DS
Graduate Program in Neuroscience, University of British Columbia, and Rehab Research Lab, G.F. Strong Rehab Centre, Vancouver, BC, Canada.
Eng
Janice J
JJ
Tokuno
Craig D
CD
Donnelly
Catherine A
CA
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D010291:Paresis / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D020521:Stroke / Q000503:physiopathology*