Maeda Yumi, Kettner Norman, Sheehan James, Kim Jieun, Cina Stephen, Malatesta Cristina, Gerber Jessica, McManus Claire, Mezzacappa Pia, Morse Leslie R, Audette Joseph, Napadow Vitaly
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, 02129, USA ; Department of Radiology, Logan College of Chiropractic/University Programs, Chesterfield, MO, 63017, USA.
Neuroimage Clin. 2013;2:313-319. doi: 10.1016/j.nicl.2013.02.001.
Carpal tunnel syndrome (CTS) is a common median nerve entrapment neuropathy characterized by pain, paresthesias, diminished peripheral nerve conduction velocity (NCV) and maladaptive functional brain neuroplasticity. We evaluated structural reorganization in brain gray (GM) and white (WM) matter and whether such plasticity is linked to altered median nerve function in CTS.
We performed NCV testing, T1-weighted structural MRI, and diffusion tensor imaging (DTI) in 28 CTS and 28 age-matched healthy controls (HC). Voxel-based morphometry (VBM) contrasted regional GM volume for CTS versus HC. Significant clusters were correlated with clinical metrics and served as seeds to define associated WM tracts using DTI data and probabilistic tractography. Within these WM tracts, fractional anisotropy (FA), axial (AD) and radial (RD) diffusivity were evaluated for group differences and correlations with clinical metrics.
For CTS subjects, GM volume was significantly reduced in contralesional S1 (hand-area), pulvinar and frontal pole. GM volume in contralesional S1 correlated with median NCV. NCV was also correlated with RD and was negatively correlated with FA within U-fiber cortico-cortical association tracts identified from the contralesional S1 VBM seed.
Our study identified clear morphometric changes in the CTS brain. This central morphometric change is likely secondary to peripheral nerve pathology and altered somatosensory afference. Enhanced axonal coherence and myelination within cortico-cortical tracts connecting primary somatosensory and motor areas may accompany peripheral nerve deafferentation. As structural plasticity was correlated with NCV and not symptomatology, the former may be a better determinant of appropriate clinical intervention for CTS, including surgery.
腕管综合征（CTS）是一种常见的正中神经卡压性神经病变，其特征为疼痛、感觉异常、周围神经传导速度（NCV）降低以及大脑功能适应性神经可塑性改变。我们评估了大脑灰质（GM）和白质（WM）的结构重组，以及这种可塑性是否与CTS患者正中神经功能改变有关。
我们对28例CTS患者和28例年龄匹配的健康对照者（HC）进行了NCV测试、T1加权结构磁共振成像（MRI）和扩散张量成像（DTI）。基于体素的形态计量学（VBM）对比了CTS患者与HC的局部GM体积。将显著的聚类与临床指标进行相关性分析，并以此为种子，利用DTI数据和概率性纤维束成像来定义相关的WM束。在这些WM束中，评估了各向异性分数（FA）、轴向扩散率（AD）和径向扩散率（RD）的组间差异以及与临床指标的相关性。
对于CTS患者，对侧S1区（手部区域）、丘脑枕和额极的GM体积显著减小。对侧S1区的GM体积与正中神经NCV相关。NCV还与RD相关，并且在从对侧S1区VBM种子确定的U形纤维皮质-皮质联合束内与FA呈负相关。
我们的研究发现CTS患者大脑存在明显的形态计量学变化。这种中枢形态计量学变化可能继发于周围神经病变和躯体感觉传入改变。连接初级躯体感觉和运动区域的皮质-皮质束内轴突连贯性和髓鞘形成增强可能伴随周围神经传入缺失。由于结构可塑性与NCV相关而非与症状相关，前者可能是CTS包括手术在内的适当临床干预的更好决定因素。
