Effects of Baclofen on Muscle Strength in Cerebral Palsy

脑性瘫痪(CP)是最常见的起源于儿童的肢体残疾，痉挛和虚弱是其主要临床症状。在过去的二十年里，这一人群的痉挛管理发生了巨大的变化，首先是引入了选择性背根切断术(SDR)，最近引入了鞘内巴氯芬(ITB)泵植入。ITB对于脊髓性痉挛患者是有效的；然而，CP的临床结果虽然通常是积极的，但不是很确定，痉挛的减少通常不那么明显，功能改善不那么显著，甚至是模棱两可的。据报道，ITB的积极作用包括放松痉挛和痉挛，这可能会减少相关的不适和改善运动的方便性。一个尚未解决的主要问题是，肌肉无力是ITB的直接影响，还是像SDR后那样，只有由于痉挛消除而出现的明显无力。在这些已经非常虚弱的患者中，虚弱的加剧可能会被证明是有问题的。本项目的具体目标是：(1)量化ITB导致的自主扭矩产生、痉挛和选择性控制的变化；(2)确定这些临床变化对功能运动结果的相互影响，以促进该疗法在脑瘫的临床应用。将检验下列假设：a)ITB将以剂量依赖的方式对八(8)个主要下肢和两(2)个具有代表性的上肢肌肉组的等长和偏心峰值扭矩产生负面影响；b)在运动任务和步态中对相对痉挛激动剂的肌肉的单独控制将以剂量依赖的方式得到反向改善；c)功能增益，包括PODCI的步态时空参数和全球功能评分的变化，将不会与剂量相关。或者，这些将取决于个人潜在的运动能力，ITB产生的痉挛和力量的变化量，以及这些变化如何相互作用来改变功能表现。我们的长期目标是通过更精确的患者选择和剂量调整，以及更多地考虑术后力量训练等辅助治疗，来改善脑瘫患者的痉挛管理。

Cerebral palsy (CP) is the most prevalent physical disability originating in childhood of which spasticity and weakness are primary clinical signs. Spasticity management in this population has changed dramatically in the past two decades, first with the introduction of selective dorsal rhizotomy (SDR) and most recently with the introduction of intrathecal baclofen (ITB) pump implantation. ITB is efficacious for persons with spasticity of spinal origin; however, the clinical results in CP, while generally positive, are less well-established, reduction in spasticity is typically less marked, and functional gains are less impressive or even equivocal. Reported positive effects of ITB include a relaxation in spasms and spasticity which may reduce associated discomfort and improve ease of movement. A major unresolved question is whether muscle weakness is a direct effect of ITB or whether only an apparent weakness occurs due to elimination of spasticity, as seen after SDR. Exacerbation of weakness could prove problematic in these patients who are already significantly weak. The Specific Aims of this project are to:(1) quantify the changes in voluntary torque production, spasticity and selective control as a result of ITB; and (2) determine the interplay of these clinical changes on functional motor outcomes so as to improve clinical application of this therapy in CP. The following hypotheses will be tested: a) ITB will have a negative effect on isometric and eccentric peak torque production of eight (8) major lower extremity and two (2) representative upper extremity muscle groups in a dose-dependent manner; b) Isolated control of muscles opposing spastic agonists during movement tasks and gait will be conversely improved in a dose-dependent manner; c) Functional gains, including changes in gait temporal-spatial parameters and the Global Function Scale of the PODCI, will not be dose-related. Alternatively, these will depend on the individual's underlying motor capabilities, the amount of change in spasticity and strength produced by ITB, and how these changes interact to alter functional performance. Our long term goal is to improve spasticity management in CP by more precise patient selection and dosage adjustment, and greater consideration of adjunct therapies such as strength training post-operatively.