书写痉挛脑功能磁共振成像研究

A functional magnetic resonance imaging study on writer's cramp

目的应用脑功能磁共振成像(fMRI)技术,观察书写痉挛患者痉挛性书写脑功能区激活特点,探讨书写痉挛可能发病机制。方法采用fMRI组块设计,分别获得10例书写痉挛患者和10名年龄、性别匹配健康对照组执行默写、手写、笔写任务时的平均脑功能激活图,同时通过一般线性分析法产生“笔写减手写”及“笔写减默写”的差异脑功能图。结果书写痉挛患者进行书写任务时,受累手对侧基底节区,特别是壳核(激活体素个数864),较健康对照组(激活体素个数54)显著激活;运动皮质(第一运动区、辅助运动区、运动前区)及同侧小脑较健康对照亦有明显激活;而进行手指写和默写任务时两组间差异并不明显;“笔写减手写”及“笔写减默写”差异脑功能图发现书写痉挛患者在除去手指写运动及语言处理相关影响后上述脑区仍有明显激活,健康对照组则皮质下结构激活消失,运动相关皮质激活亦明显减少。结论书写痉挛患者执行笔写任务时上述脑区尤其皮质下结构异常激活与书写痉挛发生存在一定关联,基底节区及相应皮质-皮质下环路功能紊乱,可能在书写痉挛发病机制中起到重要作用。

Objective In this study, functional magnetic resonance imaging （fMRI） is performed to visualize what type of brain activity correlates with writer＇ s cramp. Methods Ten patients with writer＇ s cramp and ten age- and gender-matched control subjects participated in this study, fMRI block design is used. Subjects were scanned while performing three visually instructive tasks with MR Vision 2000： （ 1 ） suppositional writing; （2） writing with finger; （3） writing with a pencil. Data were analyzed with Analysis of Functional Neuroimaging（AFNI） software for groups of patients versus controls. Results Compared with controls, patients with writer＇s cramp showed greater activation of contralateral basal ganglion （especially the putamen,864 activated voxels in patients versus 54 in controls）, ipsilateral cerebellar hemisphere, and contralateral sensorimotor, supplementary motor, premoter, primary sensory cortex in the task of writing with a pencil. There is no obvious difference in the task of writing compared with finger writing. Furthermore, these differences existed in the subtractive activated maps for ＂writing with pencil＂ minus ＂writing with finger＂, while the activation of subcortical area and insula in controls disappeared. Conclusion These results indicate that the dysfunction of basal ganglion and subcortical-cortical loop might play a pathophysiologic role in the writer＇ s cramp.