Anticipatory Motor Planning and Control of Grasp in Children with Unilateral Spastic Cerebral Palsy.

Jennifer Gutterman,Katherine Dimitropoulou,Trevor Lee-Miller,Andrew M Gordon,Kathleen M Friel

doi:10.3390/brainsci11091161

Jennifer Gutterman, Katherine Dimitropoulou + Show 3 more

Open Access

https://doi.org/10.3390/brainsci11091161

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Abstract

Children with unilateral spastic cerebral palsy (USCP) have impairments in motor planning, impacting their ability to grasp objects. We examined the planning of digit position and force and the flexibility of the motor system in covarying these during object manipulation. Eleven children with a left hemisphere lesion (LHL), nine children with a right hemisphere lesion (RHL) and nine typically developing children (controls) participated in the study. Participants were instructed to use a precision grip with their dominant/less affected hand to lift and keep an object level, with either a left, centered or right center of mass (COM) location. Digit positions, forces, compensatory torque and object roll where measured. Although children with USCP generated a compensatory torque and modulated digit placement by lift-off, their index finger was either collinear or higher than the thumb, regardless of COM location, leading to larger rolls after lift-off especially for the RHL group. The findings suggest that while the kinetics of grasp control is intact, the kinematics of grasp control is impaired. This study adds to the understanding of the underlying mechanisms of anticipatory planning and control of grasp in children with USCP and may provide insights on how to improve hand function in children with USCP.

Highlights

Anticipatory control is an important component of grasping and manipulating objects
The torques were achieved by a larger Load force (LF) and higher Center of pressure (COP) on the center of mass (COM) side, Grip Force (GF) development that was similar between digits and continued to increase after lift-off and higher COP on the COM side
When the COM location was on the right (Figure 2F), Tcom was generated in the appropriate direction, target Tcom was not achieved, even after lift onset

Summary

Introduction

Anticipatory control (motor planning) is an important component of grasping and manipulating objects. To effectively drink from a cup, one needs to scale the size and orientation of their grasp to the cup before contact, as well as scale their fingertip forces to account for the cup’s texture, weight, and orientation to successfully reach the mouth Skillful engagement in such tasks entails anticipatory control of movements at the level of kinematic (hand shaping and digit placement) and kinetic (digit force) control. Children and adolescents with unilateral spastic cerebral palsy (USCP) have significant problems in anticipatory planning of action that affect their efficiency in goal-directed functional tasks [1,2,3] They do not take end-state comfort [4] into account when planning a multi-step action such as turning a doorknob [5] or placing a cylinder on a shelf [6]. Such impairments have been shown to occur even when using the less-affected hand [1,2], suggesting higher-level planning deficits [7]

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