Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow, UP, India.
J Hepatol. 2010 Mar;52(3):348-54. doi: 10.1016/j.jhep.2009.12.012. Epub 2010 Jan 6.
BACKGROUND & AIMS: Mild cognitive and psychomotor deficit has been reported in patients with extra-hepatic portal vein obstruction. This prospective study was done to ascertain the presence of minimal hepatic encephalopathy by neuropsychological testing and its correlation with diffusion tensor imaging derived metrics, T1 signal intensity, brain metabolites in (1)H magnetic resonance spectroscopy, blood ammonia and critical flicker frequency in patients with extra-hepatic portal vein obstruction.
Neuropsychological tests, critical flicker frequency, blood ammonia, diffusion tensor imaging, T1 signal intensity and (1)H magnetic resonance spectroscopy were determined in 22 extra-hepatic portal vein obstruction and 17 healthy children. Bonferroni multiple comparison post hoc analysis was done to compare controls with patient groups.
Based on neuropsychological tests, 7/22 patients had minimal hepatic encephalopathy, and significantly increased Glx/Cr ratio, blood ammonia, mean diffusivity and globus pallidus T1 signal intensity with decreased critical flicker frequency in comparison to controls and in those without minimal hepatic encephalopathy. Cho/Cr, mI/Cr ratio and fractional anisotropy were unchanged in patient groups compared to controls. A significant inverse correlation of neuropsychological test with mean diffusivity, Glx/Cr ratio and blood ammonia and a positive correlation among mean diffusivity, blood ammonia and Glx/Cr ratio was seen.
Extra-hepatic portal vein obstruction is a true hyperammonia model with porto-systemic shunting and normal liver functions that results in minimal hepatic encephalopathy in one-third of these children. Hyperammonia results in generalized low grade cerebral edema and cognitive decline as evidenced by increased Glx/Cr ratio, mean diffusivity values and abnormal neuropsychological tests.
肝外门静脉阻塞患者存在轻度认知和运动功能障碍。本前瞻性研究旨在通过神经心理学测试确定轻微肝性脑病的存在，并将其与扩散张量成像衍生指标、T1 信号强度、磁共振波谱 1H 分析中的脑代谢物、血氨和临界闪烁频率进行相关性分析，以评估肝外门静脉阻塞患者的情况。
对 22 例肝外门静脉阻塞患儿和 17 例健康儿童进行神经心理学测试、临界闪烁频率、血氨、扩散张量成像、T1 信号强度和磁共振波谱 1H 分析。采用 Bonferroni 多重比较事后分析比较对照组和患者组。
根据神经心理学测试，7/22 例患者存在轻微肝性脑病，与对照组和无轻微肝性脑病患者相比，谷氨酸+谷氨酰胺/Cr 比值、血氨、平均弥散度和苍白球 T1 信号强度明显升高，临界闪烁频率明显降低。与对照组相比，患者组的 Cho/Cr、mI/Cr 比值和各向异性分数无变化。神经心理学测试与平均弥散度、谷氨酸+谷氨酰胺/Cr 比值和血氨呈显著负相关，平均弥散度、血氨和谷氨酸+谷氨酰胺/Cr 比值之间呈显著正相关。
肝外门静脉阻塞是一种具有门体分流和正常肝功能的真正高氨血症模型，其中三分之一的儿童会出现轻微肝性脑病。高氨血症导致弥漫性轻度脑水肿和认知功能下降，表现为谷氨酸+谷氨酰胺/Cr 比值升高、平均弥散度值升高和神经心理学测试异常。
