EVIDENCE AND TREATMENT FOR CNS SPROUTING

在以前的一项研究中，一种新的反射被描述在受试者中， 在第六颈椎或头侧遭受脊髓损伤（SCI） 根（C6;神经水平）和未恢复显著运动 在这个水平下运行（Calancie，1991）。 响应于电 刺激胫骨和/或胫后神经 四肢，短潜伏期运动反应从远端肌肉诱发 上肢的肌肉群，特别是手内肌， 腕伸肌 相反，临床上相同的损伤 在急性期，但随后恢复了C6以下的一些功能 没有表现出这样的反应，也没有健全的控制对象。 这项拟议中的研究将调查这些反射的起源， 它们可能反映了：1）预先存在的神经回路， 在正常情况下无效，但在功能上 可能反映了异常的中枢神经系统再生发芽。 我们的初步 研究表明，这些反射在神经损伤后发展， 是由于从轴突切断的下肢传入轴突发芽， 支配颈尾膨大部的运动神经元。 如果这是 正确的话，我们将证明中枢神经系统的可塑性 以前在成人脊髓中未被识别，并且可能 这将对促进再生的未来战略产生重大影响。 此外，委员会认为， 根据我们之前的研究，这种反射活动的发展 预示着功能恢复不佳，我们将尝试实施 在急性SCI阶段的治疗方案，旨在尽量减少 这些肢体间反射的发展，如果成功， 导致比这些个体经历更大的功能恢复 而他们，几乎都没有。 实验将在5年内进行，包括 急性和亚急性（<1年）损伤受试者（n= 50例受试者），以及 慢性（>1年）颈脊髓损伤（n = 100例受试者）。 我们将反复 对同一个人采取措施。 上、下游的流量特性 肢体单个运动单位（SMU）被各种下肢募集 刺激（肌肉抽搐，肌腱ta，轻触，热，冷，头发拉， 皮肤振动、电击）将是调查的主要焦点。 感觉传入纤维和脊髓长束介导的特性 这些反射也将被仔细检查。 范围和规模 在SCI后不同阶段的上肢反射将是 量化为所应用的治疗是否 影响脊髓反射组织 同样，标准化 对急性脊髓损伤研究对象进行肌肉和感觉测试 将这些行为测量与电生理学 我们获得的措施。

In a previous study a novel reflex was described in subjects who had suffered spinal cord injury (SCI) at or cephalad to the sixth cervical root (C6; neurological level) and who had not recovered significant motor function below this level (Calancie, 1991). In response to electrical stimulation of the tibial and/or posterior tibial nerves in the lower extremity, short-latency motor responses were evoked form distal muscle groups in the upper extremity, particularly intrinsic hand muscles and wrist extensors. Conversely, subjects with clinically-identical injuries at the acute stage but who subsequently recovered some function below C6 did not demonstrate such responses, nor did able-bodied control subjects. The proposed study will investigate the origin of these reflexes, in that they might reflect either: 1) pre-existing neural circuitry which is ineffectual under ordinary circumstances but which becomes functionally possible reflecting aberrant CNS regenerative sprouting. Our preliminary studies indicate that these reflexes develop after the neural lesion, and are due to sprouting from axotomized lower extremity afferent axons which innervate motoneurons of the caudal cervical enlargement. If this is correct, we will have demonstrated a capacity for CNS plasticity previously unrecognized in the adult human spinal cord, and which may well bear upon future strategies to promote regeneration. Furthermore, based on our previous study that the development of such reflex activity bodes poorly for functional recovery, we will attempt to implement a therapeutic program in the acute SCI stage which is designed to minimize the development of these interlimb reflexes, which if successful may result in greater functional recovery than these individual experience on their own (which is almost none). Experiments will be conducted over a 5 year period, and will include subjects with acute and subacute (<1 year) injury (n= 50 subjects) and chronic (>1 year) cervical SCI (n = 100 subjects). We will make repeated measures on the same individuals. The discharge properties of upper extremity single motor units (SMU) recruited by various lower extremity stimuli (muscle twitch, tendon ta, light touch, heat, cold, hair pulls, skin vibration, electric shocks) will be a major focus of investigation. Properties of the sensory afferents and spinal cord long tracts mediating these reflexes will also be examined carefully. The extent and magnitude of upper extremity reflexes at different stages after SCI will be quantified as an indicator of whether or not the applied therapy is affecting spinal cord reflex organization. Similarly, a standardized test of muscle and sensation will be given to acute SCI research subjects to correlate these behavioral measures with the electrophysiological measures which we obtain.