A natural history study evaluating the use of multimodal signal acquisition techniques to characterize movement in children and young adults with movement disorders

Clinical Center

Investigators

Abstract

Functional limb movement is initiated in the brain, where the signal then travels through the central nervous system via the subcortical brain structures and spinal cord, ultimately passing into the peripheral nervous system resulting in the coordinated activating/contracting of a set of muscles. Functional movement also relies on sensory information from the muscles and skin that are transmitted back to the brain via the spinal cord, which can also act on this sensory information. This typical information flow is disrupted in individuals with movement disorders like cerebral palsy (CP) at multiple levels, resulting in movement impairment. This protocol will measure activation at multiple points along this signal chain during isolated movements at the wrist, knee and ankle including cortical activity sensed from electroencephalography (EEG), muscle activation patterns from electromyography (EMG), muscle dynamics sensed using ultrasound via sonomyography, and kinematics via motion capture. It will evaluate the hypothesis that the measurements at each point of this signal chain during movement will be altered in children with CP compared to age-matched peers and that the quantitative relationship between each of these measurements will also be different. It will also examine the use of sonomyography from real-time ultrasound as a method to control assistive devices, including a wearable exoskeleton at the knee and closed loop functional electrical stimulation (FES) at the wrist, knee and ankle. The protocol is divided into two parts. In Part I, participants will perform single degree of freedom movement tasks using three joints (wrist flexion/extension, knee flexion-extension, and ankle plantar flexion-dorsiflexion) with and without FES assistance, as well as walking on a treadmill. Real-time ultrasound imaging will be used to monitor their muscle movement during these tasks, along with EEG, EMG and motion capture. Then, each participant will perform a target achievement task in which the position of a cursor on a screen is linked to the joint movement measured by ultrasound. The hypothesis is that the ultrasound imaging technique will enable us to extract movement intent in real-time from the participants and hence successfully track the desired targets using wrist, knee and ankle movement. In Part II, they will perform a similar target achievement task with the wrist and ankle with assistance from FES, with the intensity of the FES controlled by the real-time ultrasound. At the knee, they will do the same task with FES assistance, and with robotic exoskeleton assistance, again both controlled by ultrasound. The exploratory aim of this part is to investigate the feasibility of using real-time ultrasound imaging for control of a robotic exoskeleton and FES. To date, five total participants have been enrolled and completed both Part I and Part II of the protocol: two with CP and three healthy volunteers (HV). The goal is to have 20 total participants (10 with CP, 10 HV) complete Part I and Part II of the study, at which point we will analyze the data to evaluate our hypotheses.