Do associated reactions in the upper limb after stroke contribute to contracture formation?

Objective: To establish (1) whether associated reactions could contribute t o contracture formation and (2) whether the presence of spasticity was esse ntial for their expression, after stroke. Subjects: Subjects were 24 hemiparetics within 13 months of a stroke, unsel ected for contracture or spasticity. Main outcome measures: Associated reactions were identified by the presence of muscle activity in the affected biceps brachii and quantified as the am ount of affected elbow flexor torque produced during a moderate contraction of either the contralateral biceps brachii or the contralateral quadriceps muscles. Contracture was measured as loss of elbow joint range of motion a nd spasticity as the presence of abnormal reflex activity. Results: Associated reactions were present in at least one resting conditio n in seven subjects. During contractions of the contralateral biceps brachi i, the median amount of elbow flexor torque produced was 0.39 (interquartil e range, IQR 2.5) Nm while during contractions of the contralateral quadric eps muscle it was 0.19 [IQR 1.6) Nm. Associated reactions were not associat ed with contracture (p = 0.39) which was present in over half of the subjec ts. The incidence of associated reactions was about the same as that of spa sticity, but the two were not related (p = 0.61). Conclusions: Even though associated reactions were present in 29% of the su bjects during moderate contraction of the contralateral muscles, they were not targe, nor were they associated with contracture or spasticity, suggest ing that this phenomenon is not usually a major problem for everyday functi on after stroke.