每日一题_2022.09.12

A 50-year-old man is brought to the emergency department encephalopathic, with a Glasgow Coma Scale score of 6. History is limited but includes psychiatric illness with antipsychotic medication nonadherence. He is intubated to secure his airway and admitted to the ICU. Initial laboratory data reveal: sodium 161 mEq/L, white blood cells 11,500/μL, blood urea nitrogen 127 mg/dL, hemoglobin 17.1 g/dL, creatinine 2.8 mg/dL. Toxicology screen is negative. Head CT reveals no acute pathology. During the course of the following week, he is hydrated; his acute renal failure and hypernatremia resolve, but he remains neurologically impaired. His eyes open but there is no visual pursuit. He is adynamic in bed, and extremities are flaccid. Further neurologic testing is performed. An EEG shows a nonspecific pattern of electrical activity, with no epileptic activity. Lumbar puncture shows white blood cells 0, glucose 80 mg/dL, protein 42 g/L. Repeat head CT shows no acute pathology. Brain MRI shows extensive periventricular white matter changes and no brainstem abnormalities.

The patient’s encephalopathy is most consistent with which of the following disorders?

A. Anti-NMDA receptor encephalitis

B. Drug-related encephalopathy

C. Infectious meningoencephalitis

D. Malignant catatonia

E. Osmotic demyelination syndrome

答案解析：

涉及脑桥的渗透性脱髓鞘长期以来被认为是低钠血症管理的并发症，表现为最严重的昏迷和痉挛性四肢瘫痪。然而，最近人们认识到，其他渗透性疾病，例如高钠血症、高血糖症和低血糖症可能使患者在治疗过程中易发生髓鞘溶解。此外，已经认识到损伤范围广泛地表现为脑桥髓鞘溶解或脑桥外髓鞘溶解。因此，该疾病被重新命名为渗透性脱髓鞘综合征，以识别所有疾病。

患者的毒理学筛查未发现，病史表明他不依从药物，因此不太可能发生与药物相关的中毒性脑病。脑脊液未发现炎症迹象，因此不太可能发生传染性脑膜脑炎，同样，也不太可能发生抗 NMDA 受体脑炎（脑 NMDA 受体的一种自身免疫性疾病）。恶性紧张症在精神病患者中很常见，与该患者未见的自主神经失调和肌肉强直形式的毒性有关。

正确答案：E

补充内容：渗透性脱髓鞘综合征影像学

MRI上，最早DWI序列可出现下部桥脑的弥散受限，这可以在患者出现四肢麻痹24小时内看到，该区域此后会显示出T1低信号、T2高信号的改变，典型者轴位图像可表现出三叉样外观。

T1WI和T2WI上的信号演变需要2个星期的时间，偶尔可见钆强化，类似于多发性硬化斑块的急性期。周边纤维（腹外侧纵向纤维），以及脑室周围和软膜下区域通常不受累。类似的信号改变在基底神经节、中脑和皮质下白质中也可出现。

概括而言，受累区域的信号特征包括：

➤ T1：轻度或中度低信号

➤ T2：高信号，保留外周和皮质脊髓束

➤ FLAIR：高信号

➤ DWI：高信号

➤ ADC：信号低或信号丢失

➤ T1 C+（Gd）：通常没有增强，但偶尔有病变区域强化的报道