Mascalchi Mario, Ginestroni Andrea, Toschi Nicola, Poggesi Anna, Cecchi Paolo, Salvadori Emilia, Tessa Carlo, Cosottini Mirco, De Stefano Nicola, Pracucci Giovanni, Pantoni Leonardo, Inzitari Domenico, Diciotti Stefano
Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, Italy.
Hum Brain Mapp. 2014 Mar;35(3):819-30. doi: 10.1002/hbm.22216. Epub 2012 Dec 8.
The term leuko-araiosis (LA) describes a common chronic affection of the cerebral white matter (WM) in the elderly due to small vessel disease with variable clinical correlates. To explore whether severity of LA entails some adaptive reorganization in the cerebral cortex we evaluated with functional MRI (fMRI) the cortical activation pattern during a simple motor task in 60 subjects with mild cognitive impairment and moderate or severe (moderate-to-severe LA group, n = 46) and mild (mild LA group, n = 14) LA extension on visual rating. The microstructural damage associated with LA was measured on diffusion tensor data by computation of the mean diffusivity (MD) of the cerebral WM and by applying tract based spatial statistics (TBSS). Subjects were examined with fMRI during continuous tapping of the right dominant hand with task performance measurement. Moderate-to-severe LA group showed hyperactivation of left primary sensorimotor cortex (SM1) and right cerebellum. Regression analyses using the individual median of WM MD as explanatory variable revealed a posterior shift of activation within the left SM1 and hyperactivation of the left SMA and paracentral lobule and of the bilateral cerebellar crus. These data indicate that brain activation is modulated by increasing severity of LA with a local remapping within the SM1 and increased activity in ipsilateral nonprimary sensorimotor cortex and bilateral cerebellum. These potentially adaptive changes as well lack of contralateral cerebral hemisphere hyperactivation are in line with sparing of the U fibers and brainstem and cerebellar WM tracts and the emerging microstructual damage of the corpus callosum revealed by TBSS with increasing severity of LA.
术语“脑白质疏松症（LA）”描述了老年人中由于小血管疾病导致的常见慢性脑白质（WM）病变，其临床相关性各异。为了探究LA的严重程度是否会引起大脑皮质的某些适应性重组，我们使用功能磁共振成像（fMRI）评估了60名轻度认知障碍患者在简单运动任务期间的皮质激活模式，这些患者根据视觉评分分为中度或重度LA组（中度至重度LA组，n = 46）和轻度LA组（轻度LA组，n = 14）。通过计算脑WM的平均扩散率（MD）并应用基于纤维束的空间统计学（TBSS），在扩散张量数据上测量与LA相关的微观结构损伤。在连续轻敲右手并测量任务表现的过程中，对受试者进行fMRI检查。中度至重度LA组显示左侧初级感觉运动皮层（SM1）和右侧小脑过度激活。使用WM MD的个体中位数作为解释变量的回归分析显示，左侧SM1内的激活后移，左侧辅助运动区（SMA）、中央旁小叶以及双侧小脑脚过度激活。这些数据表明，随着LA严重程度的增加，大脑激活受到调节，在SM1内出现局部重新映射，同侧非初级感觉运动皮层和双侧小脑的活动增加。这些潜在的适应性变化以及对侧大脑半球缺乏过度激活与U纤维、脑干和小脑WM束的保留以及TBSS显示的随着LA严重程度增加胼胝体出现的微观结构损伤一致。
