Spatiotemporal kinematic parameters reflect spasticity level during forward reaching in children with hemiplegic cerebral palsy: correlation and regression analysis

Literature has identified disparities in reaching patterns between children with cerebral palsy and typically developing children. However, determining the spatiotemporal parameters that effectively quantify upper limb motor performance and examining the relationship between these parameters and spasticity level remains a challenge. This study aimed to investigate the relationship between the level of spasticity and the spatiotemporal parameters and detect which parameter is the most influenced by spasticity level. Fifty children with hemiplegic cerebral palsy participated and were asked to reach forward, at a self-selected pace, toward one target at a normalized distance under one level of accuracy. An optoelectronic system captured three-dimensional spatiotemporal parameters quantifying the movement time, velocity, strategy and smoothness of forward reaching. Spearman rank correlation coefficient was used to investigate the strength of the relationship between the level of spasticity and the spatiotemporal parameters (P˂0.05). Regression analysis was used to model the relationship between the studied variables and to investigate the impact of spasticity on the studied kinematic parameters. The level of spasticity was significantly correlated with normalized jerk score (NJS), number of movement units and peak velocity respectively (r = .0.7-0.8). The regression model was statistically significant (p < .001), and explained a significant proportion of the variances of the studied parameters especially NJS (R² = 0.972) and NMU (R² = 0.953). NJS is the most influenced parameter by the level of spasticity; therefore, it can be used as an index to quantify the impact of spasticity on reaching performance and to evaluate the effectiveness of treatment strategies on motor recovery.