Effects of Baclofen on Muscle Strength in Cerebral Palsy

脑性瘫痪（CP）是最常见的肢体残疾，起源于儿童，痉挛和虚弱是其主要临床体征。 在过去二十年中，该人群的痉挛管理发生了巨大变化，首先是引入了选择性背根切断术（SDR），最近是引入了鞘内巴氯芬（ITB）泵植入术。 ITB对脊柱源性痉挛患者有效;然而，CP的临床结果虽然通常是积极的，但不太确定，痉挛缓解通常不太明显，功能改善不太明显，甚至不明确。 报告的ITB的积极作用包括缓解痉挛和痉挛状态，这可能会减少相关不适并改善活动的便利性。 一个尚未解决的主要问题是肌无力是否是ITB的直接影响，或者是否仅由于痉挛消除而发生明显的无力，如SDR后所见。 在这些已经明显虚弱的患者中，虚弱加重可能会造成问题。 本项目的具体目的是：（1）量化ITB导致的自主扭矩产生、痉挛状态和选择性控制的变化;（2）确定这些临床变化对功能性运动结局的相互作用，以改善该疗法在CP中的临床应用。 将检验以下假设：a）ITB将以剂量依赖性方式对8个下肢大肌群和2个代表性上肢肌群的等长和离心峰值扭矩产生负面影响; B）在运动任务和步态期间，对抗痉挛性激动剂的肌肉的单独控制将以剂量依赖性方式得到相反改善; c）功能增益，包括步态时空参数和PODCI的整体功能量表的变化，将与剂量无关。 或者，这些将取决于个体的基础运动能力、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以改变功能表现。 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辅助治疗（如术后力量训练）来改善CP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.