患者男,38岁,头痛、头昏、呕吐伴行走无力、不稳,逐渐加重2月余。体检:瞳孔等大等圆,光反射敏感,四肢肌力4级,病理征(-)。实验室检查无异常。影像学检查:CT示右小脑稍高密度影,较均匀,四脑室受压缩小,幕上脑室系统对称性扩张(图1)。MRI平扫示右侧小脑半球 Male patient, 38 years old, headache, dizziness, vomiting, walking weakness, instability, and gradually increased more than 2 months. Physical examination: Pupil and other large round, light sensitive, limb muscle strength 4, pathological sign (-). No abnormal laboratory tests. Imaging examination: CT showed a slightly higher density of the right cerebellum shadow, more uniform, reduced compression of the fourth ventricle, supratentorial ventricular system symmetry expansion (Figure 1). MRI plain showed the right cerebellar hemisphere