Title: The Influence of Upper Extremity Intensive Motor Learning Intervention on Inter-Limb Coordination in Children with Unilateral Spastic Cerebral Palsy
Description: Continuous inter-limb coordination is the movement relationship between body limb segments (e.g. an arm and a leg) (Magill & Anderson, 2014) and is organized within the framework of the characteristics of the environmental conditions, the task demands, and the limb dynamics (e.g. the action capabilities of the individual) (Holt et al., 2000). When maximal coordination is achieved, stability, which is the defined as the system’s ability to offset a perturbation (Li et al., 2005), is optimized (Meyns et al., 2012). Individual coordinative relationships provide insights into neuromuscular deficiencies and their corresponding coordination difficulties (Kurz & Stergiou, 2004), such as those affecting children with cerebral palsy (CP) (Meyns et al., 2012). CP describes a group of neurodevelopmental disorders attributed to a non-progressive disturbance in the developing brain (Bax et al., 2005). Children with unilateral spastic CP (USCP), the most common subtype (Odding et al., 2006), are affected on one side of their body, experience problems with bimanual coordination, and indicate lower levels of inter-limb coordination and stability compared to their typically developing peers.

This can affect both their functional independence and quality of life (Steenbergen et al., 2008; Meyns et al., 2012). To date, no study has evaluated whether inter-limb coordination of this population during a gross motor task can be improved with treatment. The goals of this study were to evaluate continuous inter-limb coordination and stability in children with USCP compared to typically developing children (TDC) and to determine if coordination and stability of children with USCP could be improved with intensive upper extremity (UE) intervention. Constraint Induced Movement Therapy (CIMT) and Hand Arm Bimanual Intensive Therapy (HABIT) were employed to both improve UE function and determine whether inter-limb coordination and stability are also improved. A total of 33 age-matched children participated, divided evenly into three groups of Treatment (n=6, CIMT; n=5, HABIT), No-Treatment, and Typically Developing. Vicon 3-D motion capture was used to collect movement data. Continuous measures of coordination using relative phase analysis, including Mean Absolute Relative Phase (MARP) and Deviation Phase (DP) were used to quantify coordination (MARP) and stability (DP) during novel, gross motor tasks of standing and in-place marching with symmetric and asymmetric arm swing.

Results indicated that children with USCP have a lower level of coordination compared to TDC (p<0.05), but there is no difference in the stability of their patterns (p>0.05). This indicates that all children have difficulty producing consistent cyclical movements with their arms, regardless of pathology. All children also demonstrated greater difficulty coordinating their UE during the in-place marching tasks compared to the standing tasks (p<0.05), which may be due to the inherent increase in degrees of freedom associated with the addition of the lower extremities to the task. Treatment of either CIMT or HABIT improved coordination between the arms (p<0.05), but also decreased stability between the more affected arm and leg during the in-place marching tasks (p<0.05) with symmetric and asymmetric arm swing, respectively. This decrease in stability may represent the children’s inability to consistently execute the same cyclical movements for an extended period of time due to their newly learned patterns resulting from improvements in UE function after treatment.

This is the first study to identify similarities in stability between TDC and children with USCP and to demonstrate improvements in continuous, inter-limb coordination after intensive UE intervention in this pathologic population. The finding that TDC do not indicate greater stability in their motor patterns may imply that their patterns are not yet mature. Therefore, it may be efficacious to intervene at a young age to ensure correct coordinative patterns are learned and become stable as the child matures. Evidence that both function and continuous coordination between the arms are improved after intervention also suggests that with increased gross motor practice during the intervention, continuous inter-limb coordination may improve in a greater variety of tasks. Due to the prominence and accessibility of UE interventions, implementation of more gross motor tasks may be an economical way to advance coordination, which can positively impact activities of daily living and increase participation in community activities in children with USCP.