第176课 乙醇中毒—肝性脑病（Hepatic encephalopathy）

上期试题：多发性骨梗死多发于E

A、甲状腺功能亢进

B、原发性骨肿瘤

C、甲状旁腺功能亢进

D、骨转移瘤

E、镰状细胞贫血

 酗酒者脑异常表现包括脑萎缩、原发性胼胝体变性（Marchiafava-Bignami病）、韦尼克（Wernicke）脑病，渗透性髓鞘溶解症和肝硬化的并发症，如肝性脑病和凝血性疾病。

这期就单一介绍肝性脑病（Hepatic encephalopathy）

       肝性脑病是指肝功能不全患者发生的一系列神经精神异常。大多数病例与肝硬化门脉高压或存在门-体静脉分流有关，但可见于急性肝功能衰竭者，极少数见于无肝脏相关疾病的门-体静脉旁路分流患者。肝性脑病（Hepatic encephalopathy）虽然是一个临床病症，但一些神经影像技术，尤其MRI，通过识别并检测原来在正常肝脏内代谢的产物在中枢神经系统异常升高来最终诊断肝性脑病（Hepatic encephalopathy）。慢性肝性脑病（Hepatic encephalopathy）的典型MR异常表现为T1WI上苍白球高信号，这可能反映出组织中的锰浓度增高。磁共振波谱成像（MRI）升高的谷氨酰胺/谷氨酸峰结合肌醇和胆碱峰减低，反映出继发于脑内高氨血症的细胞容积内稳态失衡。最近的数据已经表明，白质异常也归因于中枢神经系统氨浓度增高，另一些MRI技术也可发现，其他序列表现正常的脑白质，磁化传递率测量值显著降低；快速FLAIR序列揭示大脑半球内 白质弥漫或局灶性高信号；DWI可发现脑白质扩散增高。所有这些MR异常在肝功能恢复正常后均可回归正常，或许反应病态下的轻度弥漫性间质脑水肿，似乎在肝性脑病（Hepatic encephalopathy）发病机制中发挥至关重要的作用。

        Hepatic encephalopathy is a series of neuropsychiatric disorders that occur in patients with liver dysfunction. The majority of cases with liver cirrhosis portal hypertension or existing door - venous shunt, but seen in acute liver failure, very few see no related liver diseases patients with venous bypass shunt door - body. Hepatic encephalopathy (Hepatic encephalopathy) is a clinical disorder, but some of the neuroimaging techniques, especially MRI, through the recognition and detection originally within normal liver metabolic product of abnormal increase in the central nervous system to the final diagnosis of Hepatic encephalopathy (Hepatic encephalopathy). The typical MR abnormality of Hepatic encephalopathy is the high signal of the white ball on T1WI, which may reflect the increase of manganese in the tissue. Magnetic resonance spectra (MRI) increased glutamine/glutamic acid in combination of muscle mellow and cholinergic peaks, reflecting the homeostatic imbalance in the cell volume of the secondary hyperaminemia of the brain. Recent data have shown that white matter abnormalities are also attributed to the increased ammonia concentration in the central nervous system, another MRI techniques can also be found, other sequences appear normal brain white matter, magnetization transfer ratio measurements significantly reduced; Rapid FLAIR sequence reveals white matter diffuse or focal high signal in cerebral hemisphere; DWI can be found to increase the proliferation of white matter. All these MR abnormalities in liver function returned to normal after all can return to normal, perhaps pathological reaction under mild diffuse interstitial cerebral edema, seems to be in Hepatic encephalopathy (Hepatic encephalopathy) play a crucial role in the pathogenesis.

      急性肝性脑病（Hepatic encephalopathy）表现为在T2WI上皮层灰质双层对称性高信号，常伴扩散受限。皮层下白质、基底节、丘脑和中脑也可受累。这些异常可导致颅内压增高和严重脑损伤，反映继发于急性脑高氨血症的细胞毒性水肿不断进展。

     Hepatic encephalopathy (acute Hepatic encephalopathy) is characterized by high - level symmetry of the cortical gray layer on T2WI and is often accompanied by diffusion limitation. Subcortical white matter, basal ganglia, thalamus and midbrain can also be affected. These abnormalities can lead to increased intracranial pressure and severe brain injury, which reflects the continuous progress of cytotoxic edema secondary to acute cerebral hyperamemia.

T1WI上特征性高信号出现在黑质、红核、苍白球

这些病变在T2WI相对不明显，但仍然可见

另一患者为弥漫性脑白质水肿（多伦多西部医院提供）

7月男孩，急性肝功能衰竭
左：头颅MRI示T2WI上脑皮质灰质对称性弥漫异常高信号

中：相应病灶在各向同性扩散加权像上呈等信号

右：表现扩散系数图为低信号，与脑细胞毒性水肿相符

本期试题：肝性脑病的正确概念应是？

A．肝功能衰竭并发精神病

B．肝功能衰竭所致的神经精神综合征

C．肝功能衰竭并发昏迷

D．肝功能衰竭并发脑水肿

E．肝脏疾病并发脑部疾病