Figure ：Progressive multifocal leukoencephalopathy lesion restricted to the posterior fossa

T2-weighted MRI shows typical hyperintense crescent-shaped progressive multifocal leukoencephalopathy lesion involving
the right middle cerebellar peduncle and white matter of the right cerebellar hemisphere.

A 47-year-old right-handed man with longstanding  HIV infection (CD4 count 105/mL; normal range 700–1,200/mL) presented with a 3-week history of  clumsiness and shaking of his right hand. Clinical examination  revealed a slow, irregular distal tremor of the  right upper limb present at rest and posture (video). Brain imaging revealed a demyelinating lesion affecting the right middle cerebellar peduncle and adjacent cerebellar white matter (figure). The CSF PCR for JC virus was strongly positive, establishing the diagnosis of progressive multifocal leukoencephalopathy (PML). Holmes tremor is a rare manifestation of PML.

     男性，47岁，有AIDS病史，近3周出现右手笨拙伴抖动。临床检查发现右上肢在静息和特定姿势出现慢速不规则远端震颤，符合Holmes震颤。头颅MRI提示右侧小脑中脚以及临近脑白质脱髓鞘样改变（图1）。脑脊液的乳多空病毒PCR检测强阳性，提示病人为进行性多灶性白质脑病。

Neurology. 2014 Jan 7;82(1):e8. 

评论：

    AIDS真是神经科的“好朋友”，很多并发症都涉及神经系统。在AIDS病人中发现脑白质有病变应该首先怀疑进行性多灶性白质脑病的可能，因为在常见的机会性感染中，乳多空病毒较易引起白质病变，而其他的机会性感染，诸如弓形体、结核或真菌，多引起肉芽肿占位性病变伴增强强化。

 知识链接：Holmes震颤

    是由丘脑、齿状核、黑质纹状体或其传导束通路间的病变而导致的一种综合征,可由多种病变引起,包括多发性硬化、卒中和肿瘤等。临床表现为不规则震颤，频率低<5Hz，可表现为静止性、意向性和姿势性，呈混合性震颤，多累及肢体近端和远端肌群。