Center for Advanced Reconstruction of Extremities (C.A.R.E.), Sahlgrenska University Hospital, Mölndal, Sweden.
Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Restor Neurol Neurosci. 2023;41(3-4):91-101. doi: 10.3233/RNN-221292.
While functional near-infrared spectroscopy (fNIRS) can provide insight into cortical brain activity during motor tasks in healthy and diseased populations, the feasibility of using fNIRS to assess haemoglobin-evoked responses to reanimated upper limb motor function in patients with tetraplegia remains unknown.
The primary objective of this pilot study is to determine the feasibility of using fNIRS to assess cortical signal intensity changes during upper limb motor tasks in individuals with surgically restored grip functions. The secondary objectives are: 1) to collect pilot data on individuals with tetraplegia to determine any trends in the cortical signal intensity changes as measured by fNIRS and 2) to compare cortical signal intensity changes in affected individuals versus age-appropriate healthy volunteers. Specifically, patients presented with tetraplegia, a type of paralysis resulting from a cervical spinal cord injury causing loss of movement and sensation in both lower and upper limbs. All patients have their grip functions restored by surgical tendon transfer, a procedure which constitutes a unique, focused stimulus for brain plasticity.
fNIRS is used to assess changes in cortical signal intensity during the performance of two motor tasks (isometric elbow and thumb flexion). Six individuals with tetraplegia and six healthy controls participate in the study. A block paradigm is utilized to assess contralateral and ipsilateral haemodynamic responses in the premotor cortex (PMC) and primary motor cortex (M1). We assess the amplitude of the optical signal and spatial features during the paradigms. The accuracy of channel locations is maximized through 3D digitizations of channel locations and co-registering these locations to template atlas brains. A general linear model approach, with short-separation regression, is used to extract haemodynamic response functions at the individual and group levels.
Peak oxyhaemoglobin (oxy-Hb) changes in PMC appear to be particularly bilateral in nature in the tetraplegia group during both pinch and elbow trials whereas for controls, a bilateral PMC response is not especially evident. In M1 / primary sensory cortex (S1), the oxy-Hb responses to the pinch task are mainly contralateral in both groups, while for the elbow flexion task, lateralization is not particularly clear.
This pilot study shows that the experimental setup is feasible for assessing brain activation using fNIRS during volitional upper limb motor tasks in individuals with surgically restored grip functions. Cortical signal changes in brain regions associated with upper extremity sensorimotor processing appear to be larger and more bilateral in nature in the tetraplegia group than in the control group. The bilateral hemispheric response in the tetraplegia group may reflect a signature of adaptive brain plasticity mechanisms. Larger studies than this one are needed to confirm these findings and draw reliable conclusions.
功能性近红外光谱（fNIRS）可提供健康和患病人群在进行运动任务时皮质脑活动的深入了解，但使用 fNIRS 评估四肢瘫痪患者重新激活的上肢运动功能的血红蛋白诱发反应的可行性仍不清楚。
本初步研究的主要目的是确定使用 fNIRS 评估具有手术恢复抓握功能的个体上肢运动任务期间皮质信号强度变化的可行性。次要目标是：1）在四肢瘫痪患者中收集初步数据，以确定 fNIRS 测量的皮质信号强度变化的任何趋势，2）比较受影响个体与年龄匹配的健康志愿者的皮质信号强度变化。具体而言，患者患有四肢瘫痪，这是一种由颈脊髓损伤引起的瘫痪，导致上下肢运动和感觉丧失。所有患者都通过手术肌腱转移恢复了抓握功能，该手术构成了大脑可塑性的独特、集中的刺激。
fNIRS 用于评估在执行两项运动任务（等长肘部和拇指弯曲）期间皮质信号强度的变化。六名四肢瘫痪患者和六名健康对照者参与了这项研究。采用块范式评估运动前皮质（PMC）和初级运动皮质（M1）中的对侧和同侧血液动力学反应。我们评估了范式期间光学信号的幅度和空间特征。通过对通道位置进行 3D 数字化并将这些位置与模板图谱大脑进行配准，可以最大限度地提高通道位置的准确性。采用短分离回归的广义线性模型方法，在个体和组水平上提取血液动力学响应函数。
在四肢瘫痪组中，PMC 中的峰值氧合血红蛋白（oxy-Hb）变化在捏合和肘部试验中似乎特别具有双侧性，而对于对照组，双侧 PMC 反应并不特别明显。在 M1/初级感觉皮质（S1）中，对捏合任务的 oxy-Hb 反应在两组中主要是对侧的，而对于肘部弯曲任务，偏侧化并不特别明显。
这项初步研究表明，该实验设置对于评估具有手术恢复抓握功能的个体在自愿上肢运动任务期间使用 fNIRS 进行脑激活是可行的。与对照组相比，与上肢感觉运动处理相关的脑区的皮质信号变化在四肢瘫痪组中更为明显且更为双侧。四肢瘫痪组的双侧半球反应可能反映了适应性大脑可塑性机制的特征。需要进行比这更大的研究来证实这些发现并得出可靠的结论。
