“缺血性脑白质病变”是慢性缺血造成的吗？
Is “ischemic white matter lesions” caused by chronic ischemia?

脑白质病变（WML）是老年人群的多发疾病，其起病隐匿，进展缓慢，无特异临床表现，多在影像 学检查时被发现。在脑部磁共振成像（MRI）上表现为脑室周围、深部白质或皮层下点、片状或弥漫性高T2及高 T2Flair异常信号灶，分布多基本对称。该类病变病因不明，目前多认为与动脉粥样硬化等血管性疾病引起的慢性 缺血有关，因此也常称作为“缺血性WML”。近年来众多研究证据证明，WML与大动脉粥样硬化及其狭窄无显著 关系，与小动脉病变的关系也不完全明确。这就对WML的慢性缺血性致病机制提出质疑。经过分析及比较研究发 现，老年期WML与广泛性脑萎缩（BA）在临床特点等方面非常相似。BA为慢性退行性神经变性疾病，这就提示 WML可能也为慢性退行性神经变性疾病，其与BA的差异可能主要在于病变组织的选择上。
White matter lesions (WML) are a kind of common disease frequently occurring in the elderly population. It is characterized by insidious onset, slow progression and no specific clinical manifestations, so it is mostly found in the imaging examination. Magnetic resonance imaging (MRI) of the brain may show spot, flaky or diffuse high T2 and high T2Flair signals in periventricular, deep white matter or subcortical areas, and the distribution of the lesions are mostly symmetrical. The pathogeny of this kind of lesions remains unknown. At present, it is generally believed to be related to chronic ischemia caused by vascular diseases such as atherosclerosis, so it is often called ischemic WML. In recent years, many studies have demonstrated that WML has no significant relationship with aortic atherosclerosis and its stenosis, and the relationship with small arterial disease is not completely clear. This calls into question the mechanism of chronic ischemic pathogenesis of WML. Through analysis and comparative study, we found that WML and generalized brain atrophy (BA) were very similar in clinical features. BA is a chronic neurodegenerative disease. This suggests that WML may also be a chronic neurodegenerative disease. The difference between it and BA may be mainly due to the selection of pathological tissues