Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex
Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex
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DOI：
10.1093/brain/awu096
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发表时间：
2014-06-01
期刊：
影响因子：
14.5
通讯作者：
Napadow, Vitaly
中科院分区：
文献类型：
--
作者：
Maeda, Yumi;Kettner, Norman;Napadow, Vitaly
脑可塑性在腕管综合征中的功能意义尚不清楚。使用功能性MRI和生物行为测试，Maeda等人将正中神经支配的手指的模糊的初级躯体感觉皮层表示与神经病学和受损的精神病学表现和辨别准确性联系起来。腕管综合征是一种正中神经卡压性神经病变，以感觉运动障碍为特征。最近的报告表明，这种综合征的特点也是功能和结构的神经可塑性在大脑的初级躯体感觉皮层。然而，这种神经可塑性和腕管综合征的功能缺陷之间的联系尚不清楚。63例年龄在20-60岁的腕管综合征患者和28例年龄和性别匹配的健康对照受试者在3 T下进行事件相关功能磁共振成像，同时向正中神经支配（第二和第三）和尺神经支配（第五）手指提供振动触觉刺激。对于每一个主题，每个数字的对侧初级躯体感觉皮层代表的趾间皮层分离距离进行了评估。我们还评估了精细运动技能的性能使用先前验证的心理性能测试（最大自愿收缩和视觉捏/释放测试）和触觉辨别能力使用四指强迫选择反应测试。这些生物行为和临床指标进行了评估，并与第二/第三趾间皮层分离距离。与健康对照组相比，腕管综合征患者对侧初级躯体感觉皮层第二/第三趾间皮层分离距离减少（P < 0.05），证实了我们先前的初步多模态神经影像学研究结果。对于心理性能测试，腕管综合征受试者表现出最大随意收缩捏强度降低（P < 0.01）和每秒捏/松循环次数减少（P < 0.05）。此外，对于四指强迫选择测试，腕管综合征受试者表现出更长的反应时间（P < 0.05），正中神经（而非尺神经）受神经支配的手指的感觉辨别准确性降低（P < 0.001）。第2、3趾间皮层间距与感觉异常程度（r =-0.31，P < 0.05）、捏/放次数（r =-0.31，P < 0.05）呈负相关，与第2、3指感觉辨别准确率（r = 0.50，P < 0.05）呈正相关。因此，减少第二/第三趾间皮层分离距离在对侧初级躯体感觉皮层与更差的触觉学（特别是感觉异常），减少精细运动技能的表现，以及更差的正中神经支配的手指的感觉辨别准确性。总之，腕管综合征患者正中神经支配手指的初级体感皮层神经可塑性确实是不适应的，是这些患者功能缺陷的基础。
The functional significance of brain plasticity seen in carpal tunnel syndrome is unclear. Using functional MRI and bio-behavioural testing, Maeda et al. link blurred primary somatosensory cortical representations of median nerve innervated fingers with symptomatology and impaired psychomotor performance and discrimination accuracy. Neuroplasticity in these patients is thus indeed maladaptive.Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the primary somatosensory cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20-60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit's contralateral primary somatosensory cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral primary somatosensory cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = -0.31, P < 0.05), and number of pinch/release cycles (r = -0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral primary somatosensory cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, primary somatosensory cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients.