The relationship between upper limb activity and impairment in post-stroke hemiplegia

Purpose. To investigate the relationship between upper limb impairments and activity limitation. Method. A cross sectional, single assessment observational study in which people with hemiplegia as a result of a stroke underwent a testing procedure in an instrumented wrist rig in which the following measures of impairment were recorded: Spasticity; motor control (ability to track a moving target); muscle activation patterns during tracking; stiffness; range of active movement and isometric muscle strength. Participants also performed clinical tests of upper limb activity (Action Research Arm Test) and hyper-tonicity (Modified Ashworth Scale). Results. Seventeen people with hemiplegia whose mean age was 57 (SD 13.4) took part. Their mean upper limb activity, measured by the Action Research Arm Test, was 19.3 (SD 11.2). Statistically significant positive relationships between level of activity and the negative features of the upper motor neuron syndrome such as motor control r=0.710 (p=0.003), active range of movement r=0.540 (p=0.025) and strength into flexion r=0.515 (p=0.034) and extension r=0.575 (p=0.016) were identified, but not with the positive features, such as spasticity or the secondary features such as stiffness. Conclusions. The negative features of the upper motor neuron syndrome appear more likely to affect upper limb activity than the positive or secondary features, but findings need confirming in different study populations, preferably with larger samples.