McKetton Larissa, Venkatraghavan Lakshmikumar, Poublanc Julien, Sobczyk Olivia, Crawley Adrian P, Rosen Casey, Silver Frank L, Duffin James, Fisher Joseph A, Mikulis David J
Division of Neuroradiology, Joint Department of Medical Imaging, University Health Network, Toronto, ON, Canada.
Department of Anaesthesia, University Health Network, Toronto, ON, Canada.
Front Neurol. 2018 Apr 6;9:226. doi: 10.3389/fneur.2018.00226. eCollection 2018.
Patients with large artery intracranial occlusive disease (LAICOD) are at risk for both acute ischemia and chronic hypoperfusion. Collateral circulation plays an important role in prognosis, and imaging plays an essential role in diagnosis, treatment planning, and prognosis of patients with LAICOD. In addition to standard structural imaging, assessment of cerebral hemodynamic function is important to determine the adequacy of collateral supply. Among the currently available methods of assessment of cerebral hemodynamic function, measurement of cerebrovascular reactivity (CVR) using blood oxygen level-dependent (BOLD) MRI and precisely controlled CO has shown to be a safe, reliable, reproducible, and clinically useful method for long-term assessment of patients. Here, we report a case of long-term follow-up in a 28-year-old Caucasian female presented to the neurology clinic with a history of TIAs and LAICOD of the right middle cerebral artery (MCA). Initial structural MRI showed a right MCA stenosis and a small right coronal radiate lacunar infarct. Her CVR study showed a large area of impaired CVR with a paradoxical decrease in BOLD signal with hypercapnia involving the right MCA territory indicating intracerebral steal. The patient was managed medically with anticoagulant and antiplatelet therapy and was followed-up for over 9 years with both structural and functional imaging. Cortical thickness (CT) measures were longitudinally assessed from a region of interest that was applied to subsequent time points in the cortical region exhibiting steal physiology and in the same region of the contralateral healthy hemisphere. In the long-term follow-up, the patient exhibited improvement in her CVR as demonstrated by the development of collaterals with negligible changes to CT. Management of patients with LAICOD remains challenging since no revascularization strategies have shown efficacy except in patients with moyamoya disease. Management is well defined for acute ischemia where the presence and the adequacy of the collateralization dictate the need for intervention. Long-term assessment in neurovascular uncoupling (i.e., chronic ischemia) may reveal improvements in CVR as the durability of compensatory collaterals improve, even in cases with no intervention. Thus, assessment of cerebrovascular hemodynamics using CVR measurements coupled with time-of-flight MR angiography can be useful in the clinical management of patients with LAICOD.
患有大动脉颅内闭塞性疾病（LAICOD）的患者面临急性缺血和慢性灌注不足的风险。侧支循环在预后中起重要作用，而影像学在LAICOD患者的诊断、治疗规划和预后中起着至关重要的作用。除了标准的结构成像外，评估脑血流动力学功能对于确定侧支供应是否充足也很重要。在目前可用的评估脑血流动力学功能的方法中，使用血氧水平依赖（BOLD）磁共振成像和精确控制的二氧化碳测量脑血管反应性（CVR）已被证明是一种安全、可靠、可重复且对患者进行长期评估具有临床实用性的方法。在此，我们报告一例28岁白种女性的长期随访病例，该患者因短暂性脑缺血发作（TIA）病史和右侧大脑中动脉（MCA）的LAICOD就诊于神经科门诊。初始结构磁共振成像显示右侧MCA狭窄和一个小的右侧放射冠腔隙性梗死灶。她的CVR研究显示大面积的CVR受损，高碳酸血症时BOLD信号出现反常下降，累及右侧MCA区域，提示脑内盗血。该患者接受了抗凝和抗血小板治疗，并通过结构和功能成像进行了9年多的随访。从感兴趣区域纵向评估皮质厚度（CT）测量值，该区域应用于显示盗血生理的皮质区域以及对侧健康半球的同一区域的后续时间点。在长期随访中，患者的CVR有所改善，表现为侧支循环的形成，而CT变化可忽略不计。LAICOD患者的管理仍然具有挑战性，因为除了烟雾病患者外，没有血管重建策略显示出疗效。对于急性缺血的管理已明确，侧支循环的存在和充足程度决定了是否需要干预。在神经血管解偶联（即慢性缺血）中的长期评估可能会发现，随着代偿性侧支循环的持久性改善，CVR会有所改善，即使在没有干预的情况下也是如此。因此，使用CVR测量结合时间飞跃磁共振血管造影评估脑血管血流动力学在LAICOD患者的临床管理中可能是有用的。
