Previous studies have shown that epidural stimulation of the lumbosacral spinal cord (scES) can re-enable lower limb volitional motor control in individuals with chronic, clinically motor complete spinal cord injury (SCI). This observation entails that residual supraspinal connectivity to the lumbosacral spinal circuitry still persisted after SCI, although it was non-detectable when scES was not provided. In the present study, we aimed at exploring further the mechanisms underlying scES-promoted recovery of volitional lower limb motor control by investigating neuroimaging markers at the spinal cord lesion site via magnetic resonance imaging (MRI). Spinal cord MRI was collected prior to epidural stimulator implantation in 13 individuals with chronic, clinically motor complete SCI, and the spared tissue of specific regions of the spinal cord (anterior, posterior, right, left, and total cord) was assessed. After epidural stimulator implantation, and prior to any training, volitional motor control was evaluated during left and right lower limb flexion and ankle dorsiflexion attempts. The ability to generate force exertion and movement was not correlated to any neuroimaging marker. On the other hand, spared tissue of specific cord regions significantly and importantly correlated with some aspects of motor control that include activation amplitude of antagonist (negative correlation) muscles during left ankle dorsiflexion, and electromyographic coordination patterns during right lower limb flexion. The fact that amount and location of spared spinal cord tissue at the lesion site were not related to the ability to generate volitional lower limb movements may suggest that supraspinal inputs through spared spinal cord regions that differ across individuals can result in the generation of lower limb volitional motor output prior to any training when epidural stimulation is provided.

中文翻译：

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临床运动完全性脊髓损伤患者的脊髓成像标志物和通过脊髓硬膜外刺激恢复自主腿运动

以前的研究表明，腰骶脊髓 (scES) 的硬膜外刺激可以重新启用慢性、临床运动完全性脊髓损伤 (SCI) 患者的下肢自主运动控制。这一观察结果表明，在 SCI 后，与腰骶脊髓回路的残余脊髓上连接仍然存在，尽管在未提供 scES 时无法检测到。在本研究中，我们旨在通过磁共振成像 (MRI) 研究脊髓病变部位的神经影像标记，进一步探索 scES 促进自主下肢运动控制恢复的机制。在硬膜外刺激器植入之前收集了 13 名慢性、临床运动完全性 SCI 患者的脊髓 MRI，并对脊髓特定区域（前、后、右、左和总脊髓）的保留组织进行了评估。硬膜外刺激器植入后，在任何训练之前，在左右下肢屈曲和踝关节背屈尝试期间评估自主运动控制。产生力量施加和运动的能力与任何神经影像学标志物无关。另一方面，特定脊髓区域的保留组织与运动控制的某些方面显着且重要地相关，包括左脚踝背屈期间拮抗（负相关）肌肉的激活幅度，以及右下肢屈曲期间的肌电图协调模式。