There is mounting experimental evidence that suggests children with hemiplegic cerebral palsy (HCP) lack the ability to properly plan their motor actions. The purpose of this investigation was to determine how these planning deficits might affect the ability of children with HCP to execute a complex sequence of actions that have different final end states in the hand/arm position. Thirteen children with HCP (age = 6.8 ± 2.9 yrs, Manual Ability Classification levels = II–IV) and 15 typically developing (TD) children (age = 5.8 ± 1.1 yrs) completed a sequential motor task that involved reaching to grasp an object and place it into six-different target positions. Each target had a biomechanically different final hand/arm position for placing the object. A three-dimensional motion capture system was used to calculate the resultant spatiotemporal kinematics of a marker that was placed on the hand. In addition, video analysis was used to quantify the child’s reaction time, end-state comfort effect, and task failures. Compared with the TD children, the children with HCP had notable deviations in their spatiotemporal kinematics when reaching for the object and placing it in the respective target positions. The children with HCP also exhibited slower reaction time, reduced end-state comfort, and increased number of task failures when placing the objects in the respective target potions. Interestingly, the children with HCP showed impaired planning on the affected as well as the less affected arm. This suggests that the inability of children with HCP to properly plan a motor action might partly arise from central deficits in their cognitive processing, and not exclusively from the peripheral deficits seen in the musculoskeletal system. Altogether our results imply that children with HCP lack the ability to plan and execute sequential motor actions.
Surkar, Hoffman, Davies, and Kurz are with the Sensorimotor Learning Laboratory, Department of Physical Therapy, Munroe Meyer Institute of Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, NE. Harbourne is with the Department of Physical Therapy, John G. Rangos School of Health Sciences, Duquesne University, Pittsburgh, PA.