Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland.
ETH Zurich, Zurich, Switzerland.
J Neurotrauma. 2023 May;40(9-10):952-964. doi: 10.1089/neu.2022.0205. Epub 2022 Sep 30.
After incomplete spinal cord injury (iSCI), the control of lower extremity movements may be affected by impairments in descending corticospinal tract function. Previous iSCI studies demonstrated relatively well-preserved movement control during simple alternating dorsiflections and plantar flexions albeit with severely reduced motor strength and range of motion. This task, however, required comparably limited fine motor control, impeding the sensitivity to assess the modulatory capacity of corticospinal control. Therefore, we introduced a more challenging ankle motor task necessitating complex and dynamic feedback-based movement adjustments to modulate corticospinal drive. Nineteen individuals with iSCI and 22 control subjects performed two different ankle movement tasks: (1) a regular, auditory-guided ankle movement task at a constant frequency as baseline assessment and (2) an irregular, visually guided ankle movement task following a pre-defined trajectory as a more challenging motor task. Both tasks were performed separately and in a randomized order. Electromyography (EMG) and kinematic data were recorded. The EMG frequency characteristics were investigated using wavelet transformations. Control participants exhibited a shift of relative EMG intensity from higher (>100 Hz) to lower frequencies (20-60 Hz) comparing the regular with the irregular movement task. There is evidence that EMG activity within these lower frequencies comprise information on corticospinal drive. The EMG frequency shift was less pronounced for the less impaired leg and absent for the more impaired leg of individuals with iSCI. The precision error during the irregular task was significantly higher for individuals with iSCI (more impaired leg: 12.34 ± 11.14%; less impaired leg: 6.93 ± 2.74%) compared with control participants (4.10 ± 0.84%). These results, along with the walking performance, correlated well with the delta frequency shift between the regular and irregular movement task in the 38 Hz band (corticospinal drive frequency) in the iSCI group, suggesting that task performance is related to the capacity to modulate corticospinal control. The irregular movement task holds promise as a tool for revealing further insights into corticospinal control of single-joint movements. It may serve as a surrogate marker for the assessment of modulatory capacity and the integrity of corticospinal control in individuals with iSCI early after injury and throughout rehabilitation.
不完全性脊髓损伤（iSCI）后，下肢运动的控制可能会受到下行皮质脊髓束功能受损的影响。先前的 iSCI 研究表明，尽管运动力量和运动范围严重降低，但在简单的交替背屈和跖屈运动中，运动控制相对较好。然而，这项任务需要相对有限的精细运动控制，这阻碍了评估皮质脊髓控制调节能力的敏感性。因此，我们引入了一项更具挑战性的踝关节运动任务，需要复杂和动态的基于反馈的运动调整来调节皮质脊髓驱动。19 名 iSCI 患者和 22 名对照组受试者分别完成了两项不同的踝关节运动任务：（1）以恒定频率进行的常规、听觉引导的踝关节运动任务作为基线评估，以及（2）遵循预定义轨迹的不规则、视觉引导的踝关节运动任务作为更具挑战性的运动任务。这两个任务是分开进行的，并且是随机顺序进行的。记录肌电图（EMG）和运动学数据。使用小波变换研究了 EMG 的频率特征。与常规运动任务相比，对照组参与者在不规则运动任务中表现出相对 EMG 强度从较高（>100 Hz）到较低频率（20-60 Hz）的转移。有证据表明，这些较低频率范围内的 EMG 活动包含皮质脊髓驱动的信息。iSCI 患者中，受损较轻的腿的 EMG 频率转移不那么明显，而受损较重的腿则没有。不规则任务期间的精度误差对于 iSCI 患者明显更高（受损较重的腿：12.34±11.14%；受损较轻的腿：6.93±2.74%），与对照组参与者（4.10±0.84%）相比。这些结果以及步行表现与 iSCI 组中规则和不规则运动任务之间 38 Hz 频段（皮质脊髓驱动频率）的 delta 频率转移密切相关，表明任务表现与调节皮质脊髓控制的能力有关。不规则运动任务有望成为揭示单关节运动皮质脊髓控制的进一步见解的工具。它可以作为评估 iSCI 患者损伤后早期和整个康复过程中调节能力和皮质脊髓控制完整性的替代标志物。
