Lei Yuming, Perez Monica A
University of Miami, Department of Neurological Surgery, The Miami Project to Cure Paralysis, Miami, Florida.
Bruce W. Carter Department of Veterans Affairs Medical Center , Miami, Florida.
J Neurophysiol. 2018 Jan 1;119(1):251-261. doi: 10.1152/jn.00542.2017. Epub 2017 Sep 20.
Most cervical spinal cord injuries result in asymmetrical functional impairments in hand and arm function. However, the extent to which reach-to-grasp movements are affected in humans with incomplete cervical spinal cord injury (SCI) remains poorly understood. Using kinematics and electromyographic (EMG) recordings in hand and arm muscles we studied the different phases of unilateral self-paced reach-to-grasp movements (arm acceleration, hand opening and closing) to a small cylinder in the more and less affected arms of individuals with cervical SCI and in age-matched controls. We found that SCI subjects showed prolonged movement duration in both arms during arm acceleration, and hand opening and closing compared with controls. Notably, the more affected arm showed an additional increase in movement duration at the time to close the hand compared with the less affected arm. Also, the time at which the index finger and thumb contacted the object and the variability of finger movement trajectory were increased in the more compared with the less affected arm of SCI participants. Participants with prolonged movement duration during hand closing were those with more pronounced deficits in sensory function. The muscle activation ratio between the first dorsal interosseous and abductor pollicis brevis muscles decreased during hand closing in the more compared with the less affected arm of SCI participants. Our results suggest that deficits in movement kinematics during reach-to-grasp movements are more pronounced at the time to close the hand in the more affected arm of SCI participants, likely related to deficits in EMG muscle activation and sensory function. NEW & NOTEWORTHY Humans with cervical spinal cord injury usually present asymmetrical functional impairments in hand and arm function. Here, we demonstrate for the first time that deficits in movement kinematics during reaching and grasping movements are more pronounced at the time to close the hand in the more affected arm of spinal cord injury. We suggest that this is in part related to deficits in muscle activation ratios between hand muscles and a decrease in sensory function.
大多数颈脊髓损伤会导致手部和手臂功能出现不对称的功能障碍。然而，对于不完全性颈脊髓损伤（SCI）患者的抓握动作受影响的程度，人们仍知之甚少。我们利用手部和手臂肌肉的运动学和肌电图（EMG）记录，研究了颈SCI患者和年龄匹配的对照组在抓取小圆柱体时，患侧和健侧手臂单侧自定节奏抓握动作的不同阶段（手臂加速、手部开合）。我们发现，与对照组相比，SCI患者在手臂加速、手部开合阶段，两侧手臂的动作持续时间都延长了。值得注意的是，与患侧较轻的手臂相比，患侧较重的手臂在手部闭合时动作持续时间进一步增加。此外，与患侧较轻的手臂相比，SCI患者患侧较重的手臂中，食指和拇指接触物体的时间以及手指运动轨迹的变异性都增加了。手部闭合时动作持续时间延长的参与者，其感觉功能缺陷更为明显。与患侧较轻的手臂相比，SCI患者患侧较重的手臂在手部闭合时，第一背侧骨间肌和拇短展肌之间的肌肉激活率降低。我们的结果表明，SCI患者患侧较重的手臂在抓握动作中，手部闭合时的运动学缺陷更为明显，这可能与EMG肌肉激活和感觉功能缺陷有关。新发现与值得注意之处颈脊髓损伤患者通常存在手部和手臂功能的不对称功能障碍。在此，我们首次证明，脊髓损伤患者患侧较重的手臂在伸手和抓握动作中，手部闭合时的运动学缺陷更为明显。我们认为，这部分与手部肌肉之间的肌肉激活率缺陷和感觉功能下降有关。
