VERTEBRAL POSITION ALTERS MUSCLE SPINDLE SENSITIVITY

描述(由申请人提供)：特发性下腰痛和脊柱手法的治疗性应用在临床、社会和经济上都产生了重大影响。据估计，超过75%的人会在一生中的某个时候经历下腰痛，每年的成本估计在200-500亿美元。荟萃分析的最新发现表明，脊椎手法可被推荐用于治疗急慢性特发性下腰痛。在美国，脊椎推拿手术的90%以上由脊椎按摩师提供，每年用于脊椎按摩服务的支出超过47亿美元。特发性下腰痛的病因和脊柱手法生理效应的潜在机制都不是很清楚。申请人最近的研究表明，椎骨的机械史改变了腰椎旁肌梭对随后的脊椎运动的敏感性。椎体滑动时的肌梭放电(平移)取决于椎骨先前是否处于卸载或加载椎体的位置，时间短至5秒。我们相信在脊柱中的这一新发现是重要的，因为运动部分不断地受到可以固定其空间方向的被动力。拟议的实验基于3个假设。(1)当椎体的线性移位先前已使椎旁肌梭卸载时，椎旁肌梭对椎体平移的敏感度增加。(2)椎体的线性移位对椎体平移的敏感性降低。(3)脊柱手法的治疗作用可能部分是通过其纠正椎旁肌梭敏感度的位置历史依赖性改变的能力来实现的。脊柱旁肌梭感觉反馈的历史依赖性改变可能导致本体感觉错误，并对节段性运动的神经控制产生不利影响。了解影响脊椎组织感觉输入的机械因素将有助于更好地了解脊椎护理的最适当的预防和治疗干预措施。脊柱手法本质上是一种生物力学干预，脊柱手法治疗特发性下腰痛的成功可能部分与特发性下腰痛的机械成分有关。

DESCRIPTION (provided by applicant): Idiopathic low back pain and the therapeutic use of spinal manipulation make a significant impact clinically, socially, and financially. It has been estimated that more than 75 percent of us will experience low-back pain at some time in our lives costing an estimated $20-$50 billion annually. Recent findings from meta-analyses indicate that spinal manipulation can be recommended clinically for the treatment of acute and chronic idiopathic low back pain. Chiropractors deliver more than 90 percent of spinal manipulations performed in the United and annual expenditures on chiropractic services exceed $4.7 billion annually. Neither the causes of idiopathic low back pain nor the mechanisms underlying the physiological effects of spinal manipulation are well understood. Recent investigations by the applicant indicate that the mechanical history of a vertebra alters the sensitivity of lumbar paraspinal muscle spindles to subsequent vertebral movement. Muscle spindle discharge in response to vertebral gliding (translation) depended upon whether the vertebra had been previously held in a position that unloaded or loaded the spindle for as little as 5 seconds. We believe this novel finding in the spine is important because motion segments are continually subjected to passive forces that can fix their spatial orientation. The proposed experiments are based upon 3 hypotheses. (1) Sensitivity of paraspinal muscle spindles to vertebral translation increases when linear displacement of the vertebra has previously unloaded the paraspinal muscle spindle. (2) Sensitivity of paraspinal muscle spindles to vertebral translation decreases when linear displacement of the vertebra has previously loaded the paraspinal muscle spindle. (3) The therapeutic effects of spinal manipulation may be mediated, in part, by its ability to correct the positional-history-dependent changes in paraspinal muscle spindle sensitivity. History-dependent alterations in sensory feedback from paraspinal muscle spindles could lead to proprioceptive errors and adversely affect neural control of segmental motion. Knowledge of mechanical factors that affect sensory input from vertebral tissues will help provide a better understanding of the most appropriate preventive and therapeutic interventions for spinal care. Spinal manipulation is inherently a biomechanical intervention and the therapeutic successes of spinal manipulation for idiopathic low back pain may relate, in part, to the mechanical component of idiopathic low back.