A 35 yr. old man coplained stomach-ache dizziness and nausea. The patient has gaze deviation nystagmus, vertical spontaneous nystagmus and positional nystagmus which was combination of direction changing and direction fiexd. He had no cranial sign beside these abnormal eye movement. For lack of physical, biochemical and neurological signs, it took about 50 days to reach to deffinit diagnosis, no matter what these abnormal eye movement indicated the exsistance of some lesion in the left and dorsal side of posteriol fossa from the beginning of disease.
The hemangioblastom in the left side culmen of vermis whose frontal end extended as for as the botom of the fourth ventricle was removed by suboccipital craniectomy.
The post-op. course was uneventful and the patient is well at present.