Relationships between impairments in strength of limb muscle actions following stroke.

To examine the relationships between impairments in limb muscle strength soon after stroke, a secondary analysis of a data base of 48 patients with stroke was undertaken. Measurements of isometric muscle strength obtained bilaterally from eight muscle actions and recorded in the data base were retrieved for analysis. Most of the strength measures correlated significantly with one another. The measures of muscle strength showed high internal consistency in each limb, on each side, and over-all. Principal components analysis and cluster analysis indicated that the closest relationships were between muscle actions of the upper limb contralateral to the stroke (the "paretic" side), limb muscle actions of the side ipsilateral to the stroke (the "nonparetic" side), and muscle actions of the lower limbs. These findings may reflect the organization of the central nervous system following stroke.