Calancie B, Alexeeva N, Broton J G, Suys S, Hall A, Klose K J
Miami Project to Cure Paralysis and Department of Neurological Surgery, University of Miami School of Medicine, Florida 33136, USA.
J Neurotrauma. 1999 Jan;16(1):49-67. doi: 10.1089/neu.1999.16.49.
Noninvasive transcranial magnetic stimulation (TMS) of the motor cortex was used to evoke electromyographic (EMG) responses in persons with spinal cord injury (n = 97) and able-bodied subjects (n = 20, for comparative data). Our goal was to evaluate, for different levels and severity of spinal cord injury, potential differences in the distribution and latency of motor responses in a large sample of muscles affected by the injury. The spinal cord injury (SCI) population was divided into subgroups based upon injury location (cervical, thoracic, and thoracolumbar) and clinical status (motor-complete versus motor-incomplete). Cortical stimuli were delivered while subjects attempted to contract individual muscles, in order to both maximize the probability of a response to TMS and minimize the response latency. Subjects with motor-incomplete injuries to the cervical or thoracic spinal cord were more likely to demonstrate volitional and TMS-evoked contractions in muscles controlling their foot and ankle (i.e., distal lower limb muscles) compared to muscles of the thigh (i.e., proximal lower limb muscles). When TMS did evoke responses in muscles innervated at levels caudal to the spinal cord lesion, response latencies of muscles in the lower limbs were delayed equally for persons with injury to the cervical or thoracic spinal cord, suggesting normal central motor conduction velocity in motor axons caudal to the lesion. In fact, motor response distribution and latencies were essentially indistinguishable for injuries to the cervical or thoracic (at or rostral to T10) levels of the spine. In contrast, motor-incomplete SCI subjects with injuries at the thoracolumbar level showed a higher probability of preserved volitional movements and TMS-evoked contractions in proximal muscles of the lower limb, and absent responses in distal muscles. When responses to TMS were seen in this group, the latencies were not significantly longer than those of able-bodied (AB) subjects, strongly suggestive of "root sparing" as a basis for motor function in subjects with injury at or caudal to the T11 vertebral body. Both the distribution and latency of TMS-evoked responses are consistent with highly focal lesions to the spinal cord in the subjects examined. The pattern of preserved responsiveness predominating in the distal leg muscles is consistent with a greater role of corticospinal tract innervation of these muscles compared to more proximal muscles of the thigh and hip.
采用非侵入性经颅磁刺激（TMS）运动皮层的方法，诱发脊髓损伤患者（n = 97）和健全受试者（n = 20，用于对比数据）的肌电图（EMG）反应。我们的目标是评估在脊髓损伤的不同水平和严重程度下，受损伤影响的大量肌肉中运动反应的分布和潜伏期的潜在差异。根据损伤部位（颈髓、胸髓和胸腰段）和临床状态（运动完全性损伤与运动不完全性损伤），将脊髓损伤（SCI）人群分为亚组。在受试者试图收缩单个肌肉时给予皮层刺激，以便既最大化对TMS产生反应的概率，又最小化反应潜伏期。与大腿肌肉（即下肢近端肌肉）相比，颈髓或胸髓运动不完全损伤的受试者更有可能在控制其足部和踝关节的肌肉（即下肢远端肌肉）中表现出自主和TMS诱发的收缩。当TMS确实在脊髓损伤平面以下节段支配的肌肉中诱发反应时，颈髓或胸髓损伤患者下肢肌肉的反应潜伏期同等延迟，这表明损伤平面以下运动轴突的中枢运动传导速度正常。事实上，颈髓或胸髓（T10及以上）水平损伤的运动反应分布和潜伏期基本无法区分。相比之下，胸腰段损伤的运动不完全性SCI受试者在下肢近端肌肉中保留自主运动和TMS诱发收缩的可能性更高，而远端肌肉无反应。当该组中观察到对TMS的反应时，潜伏期并不比健全（AB）受试者显著延长，强烈提示“神经根保留”是T11椎体及以下损伤受试者运动功能的基础。在所检查的受试者中，TMS诱发反应的分布和潜伏期均与脊髓高度局灶性损伤一致。在小腿远端肌肉中占主导的保留反应模式与皮质脊髓束对这些肌肉的支配作用相比大腿和髋部更近端肌肉的作用更大是一致的。
