Diaschisis after stroke: a novel approach with arterial spin labeling (ASL) MRI

本研究的总体目标是使用连续动脉自旋标记、CASL、灌注MRI来表征神经机能不能 并确定其对亚急性中风后轻偏瘫的作用。中风仍然是导致死亡的主要原因 尽管急性卒中的治疗和预防有所改善，患者在治疗过程中表现出相当大的变异性。 他们恢复的程度和这种变异性的机制在很大程度上仍然未知。一种机制， 一个被称为神经机能丧失的理论，在几乎世纪前被提出来解释部分的初始缺陷和部分地 断裂是指连接到大脑的未受伤大脑区域的脑血流量减少， 受伤的区域。动物模型表明，脑血流量的减少是神经元减少的结果。 相关领域的活动。在这个框架内，最初的赤字是由于神经联系不能和失去 在损伤部位的功能，而恢复发生在神经连接不能逆转。以前的研究尝试 在人类中的现象依赖于PET和SPECT，这是昂贵的，不是广泛可用的，并需要 放射性示踪剂的注入，限制了使用的频率和实用性。因此， 神经机能不能的研究及其与卒中缺陷和卒中恢复的相关性仍有待确定。这里我们 我建议使用动脉自旋标记（ASL）来研究亚急性期和慢性期患者的神经机能不能 在偏瘫中风之后。ASL是一种非侵入性MR方法，可量化血流。迄今为止，它已被用于 测量被血管闭塞性疾病损害的脑血流量，CBF。在这里，我们提出一个小说 ASL用于检测由于神经元活动减少而导致的CBF减少。该补助金的主要目的是 证明对侧小脑（交叉小脑神经联系不能）和 对侧半球然后我们将这些变化与中风后3至4周的初始运动缺陷相关联 6个月时恢复程度良好。

The overall goal of this study is to use continuous arterial spin labeling, CASL, perfusion MRI to characterize diaschisis and determine its contribution to hemiparesis after subacute stroke. Stroke remains the leading cause of death worldwide despite improvements in acute stroke treatment and prevention. Patients show considerable variability in the degree to which they recover and the mechanisms underlyingthis variabilityare still largely unknown. One mechanism, termed diaschisis, was proposed almost a century ago to explain part of the initial deficit and the ability topartially recover from it. Diaschisis refers to a reduction of cerebral blood flow in uninjured brain regions that are connected to the area of injury. Animal models suggest that the reduction in cerebral blood flow is the result of decreased neuronal activity in the connected areas. Withinthis framework, the initial deficit is due to combination of diaschisis and the loss of function at the lesion location, whereas recovery occurs as diaschisis reverses. Previous attempts to study this phenomenon in humans have relied on PET and SPECT, which are expensive, not widelyavailable, and require injection of radioactive tracers, limitingthe frequency and practicality of use. As a result, there have been relatively few studies of diaschisis and thus its relevance to stroke deficit and stroke recovery remains to be determined. Here we propose to use arterial spin labeling, ASL, to investigatediaschisis in patients in the subacute and then chronic phases after hemiparetic stroke. ASL is non-invasive MR method that quantifies blood flow. To date it has been used to measure cerebral blood flow, CBF, that has been compromised by vascular occlusive disease. Here we propose a novel application of ASL for detection of decreases in CBF due to reduction in neuronal activity. The main aim of this grant is to demonstrate reductions in CBF in the contralateral cerebellum (crossed cerebellar diaschisis)and in the contralesional hemisphere. We will then correlate these changes with initial motor deficit in 3 to 4 weeks after stroke and with degree of recovery at 6 months.