Patients with a presumed transient ischemic attack should undergo a neuroimaging evaluation within 24 hours of their symptom onset, preferably with magnetic resonance imaging, according to new recommendations for evaluating the disorder.
The guideline, issued by the American Heart Association/American Stroke Association, redefines transient ischemic attack (TIA) as an urgent problem worthy of immediate treatment, rather than a minor issue that can be managed with watchful waiting. New imaging methods have shown that many TIAs are associated with new infarcts, and that up to 15% of patients will have a major stroke within 3 months of a TIA, with almost half of those occurring within 48 hours.
“Often, health professionals consider TIAs benign, but regard strokes as serious,” wrote Dr. J. Donald Easton, writing chair of the statement and professor and chair of the department of clinical neurosciences at Alpert Medical School of Brown University and the Rhode Island Hospital in Providence, R.I. “Those views are incorrect. Stroke and TIA are on a spectrum of serious conditions involving brain ischemia. Both are markers of reduced cerebral blood flow and an increased risk of disability and death. However, TIAs offer an opportunity to initiate treatment that can forestall the onset of permanently disabling injury.”
TIAs have in the past been temporally defined as a focal cerebral ischemic event with symptoms lasting less than 24 hours. The new description defines TIA from a tissue-based stance, as “a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction.”
The tissue-based description is important, according to the recommendation committee, because distinguishing TIA by a time limit is misleading and can be inaccurate. “Time-based definitions unproductively focus diagnostic attention on the temporal course rather than the underlying pathophysiology. The key diagnostic issue in patients with cerebral ischemic events is not how long the event lasted, but rather the cause of the ischemia and whether cerebral injury occurred.” A tissue-based definition also encourages the use of neurodiagnostic tests to identify brain injury and its cause, while the time-based definition encourages a “wait and see” approach, during which further ischemic insult may occur, they added.
Immediate evaluation not only offers the ability to discover the exact extent of any new infarct, but the chance to identify the TIA’s cause. Testing should investigate whether there is any intracranial or extracranial vessel disease, and include a cardiac evaluation.
The committee recommended the following diagnostic evaluation, based on the new definition:
– Patients with TIA should undergo neuroimaging within 24 hours of symptom onset, preferably by MRI with diffusion-weighted imaging. If these are not available, computed axial tomography should be performed.
– The evaluation should include noninvasive testing of the cervicocephalic vessels.
– Noninvasive testing of the intracranial vessels is reasonable when the knowledge of transcranial vessel disease would alter management decisions. This may be done by carotid ultrasound/transcranial Doppler, magnetic resonance angiography, or computed tomography angiography.
– An electrocardiogram should be performed as soon as possible, especially in patients in whom the initial workup has shown no immediate cause of the TIA.
– Consider hospitalization of TIA patients if they present within 72 hours of the event with any of the following criteria: ABCD2 score of 3 or higher; ABCD2 score of 0-2 and uncertainty that a diagnostic work-up can be completed within 2 days; ABCD2 score of 0-2 and other evidence that the TIA was caused by focal ischemia.
The statement will appear in the June issue of Stroke (doi:10.1161/STROKEAHA.108.192218).
The writing committee also included members of the U.S. Cardiovascular Surgery and Anesthesia Council, the U.S. Cardiovascular Radiology and Intervention Council, the U.S. Cardiovascular Nursing Council, and the U.S. Atherosclerotic Peripheral Vascular Disease Working Group.
Members of the writing committee disclosed having conflicts of interest with a number of pharmaceutical and medical device manufacturers.
Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
根据短暂性脑缺血发作（TIA）的最新评估建议，疑似TIA患者应在症状发生后24小时内接受神经影像学评估，最好是磁共振成像（MRI）检查。
该指南是由美国心脏学会（AHA）和美国卒中学会（ASA）联合发布的。指南重新定义TIA为一种值得立即进行治疗的急症，而不是仅给予观察性等待的小病。新的影像学方法已经显示，许多TIA与新的梗死灶相关，且15%的患者将在TIA后的3个月内发生大卒中，其中几乎一半发生在48小时内。
“医护人员常常认为TIA是良性的，而认为卒中是严重的，”指南的执笔委员会主席、布朗大学阿尔坡特医学院和罗得岛州医院临床神经科学系教授暨主任J. Donald Easton博士这样写道，“这些观点是错误的。卒中和TIA是同一谱系疾病，这是一类包括脑缺血在内的严重疾病。这两种病都是脑血流量减少、残疾及死亡危险增加的标志物。然而，TIA阶段提供了一个启动治疗以遏制永久性致残性损伤发生的机会。”
过去，TIA被定义为一种局灶性的脑缺血事件，其症状持续不超过24小时。新的描述则从以组织为基础的角度定义TIA，TIA是“一种由大脑局部、脊髓或视网膜缺血引起的短暂性发作的神经功能障碍，不存在急性梗死。”
根据建议委员会的意见，以组织为基础的描述很重要，因为根据时间来界定TIA容易产生误导，是不准确的。“以时间为基础的定义，毫无成效地将诊断注意力集中在短暂性过程，而不是疾病本身的病理生理学变化。对于发生脑缺血事件的患者，诊断的要点并不是该事件持续多久，而是缺血的原因以及是否发生了脑损伤。”一个以组织为基础的定义还能促使应用神经诊断学实验来检出脑损伤及其病因，而以时间为基础的定义则鼓励“观望”策略，岂不知在等待期间有可能发生更多的缺血事件，他们补充道。
即刻评估不但为发现任何新发梗死灶并确定其确切范围提供了可能性，而且提供了找出TIA“元凶”的机会。所进行的检查应评估是否存在任何颅内或颅外血管病变，并应包括心脏评估。
基于TIA新定义，委员会建议进行下列诊断性评估：
– TIA患者应在症状发生后24小时内接受神经影像学检查，最好是带弥散加权像（DMI）的MRI。如果没有上述条件，那么应进行轴位CT扫描。
– 评估内容应包括对头颈部血管的无创性检查。
– 若存在经颅血管疾病，将会改变治疗策略，因而对颅内血管进行无创性检查是合理的。检查方法包括颈动脉超声/经颅多普勒、磁共振血管成像或CT血管成像。
– 心电图应尽早进行，尤其是对于初始病情检查未发现TIA直接原因的患者。
– 如果TIA患者在事件发生后72小时内满足下列指标，考虑住院治疗：ABCD2评分≥3；ABCD2评分为0～2，但不确定诊断性检查可以在２天之内完成；ABCD2评分为0～2，且有其他证据显示TIA是由局灶性缺血引起的。
该指南将发表在2009年6月份的《卒中》（Stroke）杂志上(doi:10.1161/STROKEAHA.108.192218)。
执笔委员会还包括的美国心血管手术与麻醉委员会、美国心血管放射与干预委员会、美国心血管护理委员会和美国动脉粥样硬化性外周血管病工作组的成员。
执笔委员会的成员宣称与许多制药企业和医疗器械生产厂商之间存在利益关系。
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