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

项目摘要 脑瘫是小儿最常见的运动障碍。最常见的亚型，脑性偏瘫 麻痹（HCP）的特征在于身体一侧的感觉运动功能障碍，特别是影响上肢 四肢上肢的感觉运动控制受损会对教育机会产生负面影响， 参与日常活动，未来的工作前景和自尊。因此，上肢，特别是 手是职业和物理治疗的重要目标。尽管作出了这些努力， 上肢的缺陷通常持续到成年，并导致终身限制。主要贡献者 损伤是深刻的弱点。儿童的相对力量不足随着年龄的增长而增加， 成年不幸的是，这种弱点的潜在生理原因还没有得到很好的理解。可能 导致CP中肌肉无力的因素包括自主兴奋肌肉的能力降低，过度兴奋肌肉， 拮抗剂的共激活和改变的肌肉形态。这项研究的目的是确定相对 这些损伤机制对观察到的HCP儿童虚弱的贡献。 每个参与者将被要求完成一组实验。在第一个实验中， 手部肌肉过度兴奋，表现为痉挛、过度共激活或延迟松弛 时间将被评估。为了量化痉挛，一个定制的伺服控制夹具将施加控制拉伸的 通过掌指关节（MCP）的旋转，目标手指肌肉。痉挛性反射反应 将根据阻力扭矩和手指肌肉的激活进行量化，如用表面测量的 肌电图（EMG）。共激活和弛豫时间将从在过程中记录的EMG信号测量。 手固定在夹具内时，MCP关节周围的自主等长扭矩产生。等速 还将评估宫缩以评估功率的不足。对于第二个实验， 关键的外部手指肌肉的自主激活将通过抽搐内插和中枢神经系统检查。 活化比技术。表面电刺激将叠加在自发激活的 指定手指肌肉产生最大等长手指力。麻痹手的激活值将 与非麻痹手的手和在典型发育儿童中测量的值进行比较。这些 实验数据将被用于开发特定主题的神经力学计算机模型的手， OpenSim。肌肉形态，如长度和横截面积，将用超声测量， 包含在每个定制模型中。计算机模型将用于确定指尖的灵敏度 强度和控制不同的损害机制。总之，这项研究的结果将有助于更好地 为脑瘫儿童提供当前和未来的康复技术。

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.