Identifying the Neuromuscular Origins of Hand Muscle Weakness in Children with Hemiplegic Cerebral Palsy

确定偏瘫脑瘫儿童手部肌肉无力的神经肌肉起源

• 批准号: 10314526
• 负责人: Miranda Claire Ludovice
• 金额: $ 4.16万
• 依托单位: NORTH CAROLINA STATE UNIVERSITY RALEIGH
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10314526
• 关键词: Identifying; Neuromuscular; Origins; Hand; Muscle

PROJECT SUMMARY Cerebral palsy is the most common pediatric motor disorder. The most prevalent subtype, hemiplegic cerebral palsy (HCP), is characterized by sensorimotor dysfunction on one side of the body, especially affecting the upper limb. The impaired sensorimotor control of the upper limb can negatively impact educational opportunities, participation in daily activities, future job prospects, and self-esteem. For this reason, the upper limb, particularly the hand, is a significant target for occupational and physical therapy. Despite these efforts, substantial functional deficits in the upper limb often persist into adulthood and contribute to lifelong limitations. A main contributor to impairment is profound weakness. The relative strength deficits increase with age in children and extend into adulthood. Unfortunately, the underlying physiological causes of this weakness are not well understood. Possible contributors to muscle weakness in CP include a diminished ability to voluntarily excite the muscles, excessive co-activation of antagonists, and altered muscle morphology. The goal of this research is to determine the relative contributions of these impairment mechanisms to observed weakness in children with HCP. Each participant will be asked to complete a set of experiments. In the first experiment, possible involuntary hyperexcitability of hand muscles, as manifested as spasticity, excessive coactivation, or delayed relaxation time, will be assessed. To quantify spasticity, a custom servo-controlled jig will impose controlled stretch of the targeted finger muscles through rotation of the metacarpophalangeal (MCP) joints. The spastic reflex response will be quantified in terms of resistance torque and activation of finger muscles, as measured with surface electromyography (EMG). Coactivation and relaxation time will be measured from EMG signals recorded during voluntary isometric torque generation about the MCP joints with the hand fixed within the jig. Isokinetic contractions will also be assessed to evaluate deficits in power. For the second experiment, possible deficits in voluntary activation of key extrinsic finger muscles will be examined through twitch interpolation and central activation ratio techniques. Surface electrical stimulation will be superimposed on the voluntary activation of specified finger muscles to produce maximum isometric finger force. Activation values for the paretic hand will be compared with those of the non-paretic hand and the values measured in typically developing children. These experimental data will be used to develop subject-specific neuromechanical computer models of the hand in OpenSim. Muscle morphology, such as length and cross-sectional area, will be measured with ultrasound for inclusion in each custom model. The computer models will be used to determine the sensitivity of fingertip strength and control to different impairment mechanisms. Together, the results of this study will help to better inform current and future rehabilitation techniques in children with cerebral palsy.

项目总结