Characteristics of associated reactions in people with hemiplegic cerebral palsy

To investigate the relationship between associated reactions and a) spasticity, b) contracture and c) coordination.

Associated reactions were measured as magnitude of muscle activity in the affected limb during a 50% maximum voluntary contraction of muscles in the unaffected limb. Spasticity was measured as hyper-reflexia during passive muscle stretch, coordination as performance during a tracking task, and contracture as loss of range of motion. Chi-square analysis was used to examine the association between associated reactions and spasticity, and linear regression to examine the relationship between associated reactions and spasticity, coordination and contracture.

Twenty-three people with hemiplegic cerebral palsy aged from 15 to 47 years (mean [SD]: 29 years [9]) participated. Thirteen participants exhibited spasticity, and six participants exhibited associated reactions. Five of the six participants with associated reactions also had spasticity (χ2=2.37, p=0.12). Associated reactions were highly correlated with spasticity (r=0.77, p=0.001), but not with contracture (r=0.35, p=0.29) or coordination (r=-0.31, p=0.30).

Although 27% of participants exhibited associated reactions, and these were mostly small, associated reactions appear to be an expression of spasticity in hemiplegic cerebral palsy.