患者，女性，５７岁。间断性头晕，呕吐，进行性加重８年，症状与头位有关，抬头时出现或加重，近３年被迫昼夜保持低头胸膝卧位。曾头颅ＣＴ平扫两次均报告未见异常。查体：神清语利，被动体位，极度消瘦，视乳头无水肿，双眼球水平震颤，神经系统未见其它异常。脑ＣＴ平扫显 Patient, female, 57 years old. Intermittent dizziness, vomiting, progressive exacerbation of 8 years, the symptoms associated with the first bit, when appearing or exacerbated by the last 3 years were forced to keep bow and knee supine position around the clock. Had skull CT scan twice were reported no abnormalities. Physical examination: God Qing language Lee, passive position, extremely thin, no swelling of the optic nerve, both eyes tremor tremor, the nervous system, no other abnormalities. Brain CT plain scan