Cheema Ikreet, Switzer Aaron R, McCreary Cheryl R, Hill Michael D, Frayne Richard, Goodyear Bradley G, Smith Eric E
Department of Clinical Neurosciences, University of Calgary, Calgary, Canada.
Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services, Calgary, Canada; Department of Radiology, University of Calgary, Calgary, Canada; Department of Clinical Neurosciences, University of Calgary, Calgary, Canada.
J Neurol Sci. 2017 Apr 15;375:248-254. doi: 10.1016/j.jns.2017.02.004. Epub 2017 Feb 3.
The magnitude of the blood oxygen dependent level (BOLD) functional MRI (fMRI) response to visual stimulation is reduced in the small vessel disease cerebral amyloid angiopathy (CAA), reflecting impaired vascular reactivity. We determined whether BOLD responses were reduced in another small vessel disease, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).
BOLD fMRI data were collected using a visual stimulus (contrast-reversing checkerboard) and motor task (finger-tapping). The amplitude of BOLD responses in the visual cortex (visual stimulus) and motor cortex (motor task) were compared between 5 CADASIL, 18 CAA and 18 control subjects, controlling for age and hypertension.
BOLD response varied by group for the visual stimulus (p<0.001) but not the motor task (p=0.47). After adjusting for age and hypertension, the estimated mean visual cortex BOLD amplitude response was 3.95% in CADASIL (95% confidence interval, CI 3.15-4.75%), 1.73% in CAA (95% CI 1.19-2.27%), and 2.88% (95% CI 2.39-3.37%) in controls. In CADASIL, the visual BOLD response was greater than in CAA (p<0.001) and controls (p=0.04).
We observed increased and unchanged BOLD amplitude responses in the visual and motor cortices of CADASIL patients, respectively. This suggests that cortical blood flow regulation by neuronal activity may be relatively preserved in CADASIL, in contrast to CAA where occipital vascular reactivity is impaired. Cortical vascular reactivity in CADASIL may be preserved because the disease-related injury is primarily subcortical, whereas increased activation may reflect compensatory mechanisms for subcortical injury.
脑小血管病脑淀粉样血管病（CAA）中，血氧依赖水平（BOLD）功能磁共振成像（fMRI）对视觉刺激的反应幅度降低，反映了血管反应性受损。我们确定在另一种小血管病——伴有皮质下梗死和白质脑病的常染色体显性遗传性脑动脉病（CADASIL）中，BOLD反应是否降低。
使用视觉刺激（对比度反转棋盘格）和运动任务（手指敲击）收集BOLD fMRI数据。比较了5例CADASIL患者、18例CAA患者和18例对照者在视觉皮层（视觉刺激）和运动皮层（运动任务）中BOLD反应的幅度，并对年龄和高血压进行了控制。
视觉刺激时BOLD反应因组别而异（p<0.001），但运动任务时无差异（p=0.47）。在调整年龄和高血压因素后，CADASIL患者视觉皮层BOLD幅度反应的估计平均值为3.95%（95%置信区间，CI 3.15-4.75%），CAA患者为1.73%（95%CI 1.19-2.27%），对照组为2.88%（95%CI 2.39-3.37%）。在CADASIL患者中，视觉BOLD反应大于CAA患者（p<0.001）和对照组（p=0.04）。
我们分别观察到CADASIL患者视觉和运动皮层中BOLD幅度反应增加和不变。这表明与CAA患者枕叶血管反应性受损不同，CADASIL患者中神经元活动对皮质血流的调节可能相对保留。CADASIL患者的皮质血管反应性可能得以保留，因为与疾病相关的损伤主要在皮质下，而激活增加可能反映了对皮质下损伤的代偿机制。
