Lotfi J, Meyer J S
Cerebral Blood Flow Laboratory, VAMC, Houston, Texas.
Cerebrovasc Brain Metab Rev. 1989 Spring;1(1):2-25.
The nervous system is particularly susceptible to the harmful effects of alcohol. These include Wernicke-Korsakoff syndrome, which is related to thiamine deficiency secondary to chronic alcohol abuse. Other neurotoxic effects of alcohol with cognitive impairments include delirium tremens, alcoholic seizures or "rum fits," and alcoholic neuropathies. It has become recognized in recent years that alcohol and its metabolites directly damage the nervous system even in the absence of nutritional deficiencies. Cerebral blood flow (CBF) measurements provide a noninvasive indirect monitor of cerebral metabolic activity. It has been shown conclusively that CBF measured by the 133Xe inhalation method is decreased in chronic alcoholism, correlating well with the amount of alcohol consumed. With abstinence, CBF returns toward normal levels provided the neurotoxic effects of chronic alcoholism are of recent onset. Clinical and pathological studies show significant loss of brain volume with ventricular dilatation after alcohol abuse even among young "social" drinkers. This toxic effect of alcohol is accompanied by varying degrees of cognitive impairments ranging from slight memory loss to frank dementia. Both the decrease in brain volume and the cognitive impairments, which occur with or without nutritional deficiency, are to a large extent reversible with abstinence and nutritional supplementation. Alcohol appears to accelerate age-related declines in CBF while nutritional deficiencies enhance the neurotoxic effects of alcohol. Measurements of local CBF (LCBF) and partition coefficients (L lambda) in deep cerebral structures, including the hypothalamus, thalamus, forebrain nuclei, and limbic system, can be achieved utilizing three-dimensional methods after inhalation of stable xenon as a contrast medium combined with serial computed tomographic imaging of the brain. Among chronic alcoholics, there are significant and diffuse reductions in cortical and subcortical gray matter CBF that are especially remarkable in hypothalamus and substantia innominata, which includes the nucleus basalis of Meynert, a major source of cholinergic input to neocortex and hippocampus. Reductions in LCBF are measurable in cognitively impaired patients with and without Wernicke-Korsakoff syndrome. Reductions of CBF include white matter and are more severe in patients with Wernicke-Korsakoff syndrome. Both types of encephalopathy improve with treatment, but recovery is usually more rapid and complete if nutritional deficiency is absent. Alcohol also appears to be a risk factor for stroke, possibly by depleting neuronal reserves and unfavorably influencing cardiovascular risks.
神经系统对酒精的有害影响尤为敏感。这些影响包括韦尼克 - 科尔萨科夫综合征，它与慢性酒精滥用继发的硫胺素缺乏有关。酒精对认知功能有损害的其他神经毒性作用包括震颤谵妄、酒精性癫痫发作或“rum fits”以及酒精性神经病。近年来人们已经认识到，即使在没有营养缺乏的情况下，酒精及其代谢产物也会直接损害神经系统。脑血流量（CBF）测量为脑代谢活动提供了一种非侵入性的间接监测手段。已经确凿地表明，通过吸入133Xe方法测量的慢性酒精中毒患者的CBF会降低，且与饮酒量密切相关。戒酒后，如果慢性酒精中毒的神经毒性作用是近期发生的，CBF会恢复到正常水平。临床和病理研究表明，即使在年轻的“社交”饮酒者中，酒精滥用后也会出现脑容量显著减少和脑室扩张。酒精的这种毒性作用伴有不同程度的认知功能损害，从轻微的记忆力减退到明显的痴呆。无论是否存在营养缺乏，脑容量减少和认知功能损害在很大程度上都可以通过戒酒和营养补充得到逆转。酒精似乎会加速与年龄相关的CBF下降，而营养缺乏会增强酒精的神经毒性作用。在吸入稳定的氙作为造影剂并结合脑部系列计算机断层扫描成像后，利用三维方法可以测量包括下丘脑、丘脑、前脑核和边缘系统在内的深部脑结构中的局部脑血流量（LCBF）和分配系数（L lambda）。在慢性酒精中毒患者中，皮质和皮质下灰质CBF存在显著且弥漫性的降低，在下丘脑和无名质中尤为明显，无名质包括迈内特基底核，它是新皮质和海马胆碱能输入的主要来源。在有或没有韦尼克 - 科尔萨科夫综合征的认知功能受损患者中，均可测量到LCBF降低。CBF降低包括白质，在韦尼克 - 科尔萨科夫综合征患者中更为严重。两种类型的脑病经治疗后均可改善，但如果不存在营养缺乏，恢复通常会更快且更完全。酒精似乎也是中风的一个危险因素，可能是通过消耗神经元储备并对心血管风险产生不利影响。
