Department of Diagnostic Imaging, University Health Network, University of Toronto, Ontario, Canada.
AJNR Am J Neuroradiol. 2011 Feb;32(2):413-8. doi: 10.3174/ajnr.A2290. Epub 2010 Nov 18.
Acute hyperammonemic encephalopathy has significant morbidity and mortality unless promptly treated. We describe the MR imaging findings of acute hyperammonemic encephalopathy, which are not well-recognized in adult patients.
We retrospectively reviewed the clinical and imaging data and outcome of consecutive patients with documented hyperammonemic encephalopathy seen at our institution. All patients underwent cranial MR imaging at 1.5T.
Four patients (2 women; mean age, 42 ± 13 years; range, 24-55 years) were included. Causes included acute fulminant hepatic failure, and sepsis with a background of chronic hepatic failure and post-heart-lung transplantation with various systemic complications. Plasma ammonia levels ranged from 55 to 168 μmol/L. Bilateral symmetric signal-intensity abnormalities, often with associated restricted diffusion involving the insular cortex and cingulate gyrus, were seen in all cases, with additional cortical involvement commonly seen elsewhere but much more variable and asymmetric. Involvement of the subcortical white matter was seen in 1 patient only. Another patient showed involvement of the basal ganglia, thalami, and midbrain. Two patients died (1 with fulminant cerebral edema), and 2 patients survived (1 neurologically intact and the other with significant intellectual impairment).
The striking common imaging finding was symmetric involvement of the cingulate gyrus and insular cortex in all patients, with more variable and asymmetric additional cortical involvement. These specific imaging features should alert the radiologist to the possibility of acute hyperammonemic encephalopathy.
急性高氨血症性脑病如不及时治疗，发病率和死亡率均较高。我们描述了成人患者中尚未被充分认识的急性高氨血症性脑病的磁共振成像（MRI）表现。
我们对我院收治的经证实的高氨血症性脑病连续患者的临床和影像学数据及结局进行了回顾性分析。所有患者均在 1.5T 行颅脑 MRI 检查。
4 例患者（2 例女性；平均年龄 42 ± 13 岁；范围 2455 岁）纳入本研究。病因包括急性暴发性肝衰竭、伴有慢性肝衰竭的脓毒症和心肺移植后出现各种全身并发症。患者的血氨水平为 55168 μmol/L。所有患者均双侧对称存在信号异常，常伴有岛叶和扣带回的弥散受限，皮质其他部位也常受累，但更具多变性和不对称性。1 例患者存在皮质下白质受累。另 1 例患者显示基底节、丘脑和中脑受累。2 例患者死亡（1 例发生暴发性脑水肿），2 例患者存活（1 例神经功能完整，另 1 例存在严重智力障碍）。
所有患者的突出共同影像学表现为扣带回和岛叶的对称受累，伴有更具多变性和不对称性的皮质其他部位受累。这些特定的影像学特征应使放射科医生警惕急性高氨血症性脑病的可能性。
