Quantification of Upper Extremity Motor Impairments in Pediatric Hemiplegia

Pediatric-onset stroke leads to pediatric hemiplegia (PH), causing motor impairments on one side of the body. Childhood is a critical period for motor, cognitive, and social development. As such, impairments that limit a child’s ability to engage within his/her environment can have devastating consequences as the child develops into adolescence and adulthood. Motor impairments in this population include weakness, movement synergies, and coupling movement across limbs, all of which limit independence with functional mobility throughout the lifespan. Crucial tasks such as reaching and grasping, which are required for countless daily activities including eating, dressing, and participating in the classroom, become limited or impossible. Motor impairments have been shown to vary based on injury time before, during, or after birth. Retention of high resolution ipsilateral corticospinal projections in earlier injuries may reduce the presence of the flexion synergy or involuntary joint coupling of shoulder abduction (SABD) with elbow, wrist, and finger flexion seen in later injuries. Previous work provides early evidence of the differential presentation of impairments based on injury timing in isometric conditions however the presentation of these impairments during functional reach and grasping movements is largely unknown. Therefore, the aim of the proposed study is to quantify the expressions of the flexion synergy and across limb coupling movements during a dynamic functional task as a function of SABD load and time of injury. Haptic robotics provide an avenue to assess the effect of injury timing on motor function by measuring kinematics and kinetics of reaching and grasping while modulating the amount of SABD torque required to complete the task. Utilizing a haptic robotic device, six-degree-of-freedom load cell, motion capture system, pressure mat, and surface EMG electrodes, this work proposes to: 1) characterize upper extremity reaching distance and hand opening/closing, as modulated by SABD load level and time of injury and 2) determine how the expression of across limb coupling movement varies as a function of SABD load and time of injury. Knowledge gained from elucidating the differential presentation of movement impairments in subpopulations of PH is essential to begin developing targeted, time of injury-specific interventions that have the greatest potential to improve functional mobility in this population.