[Improvement in hemiballism after transient hypoxia in a case of subthalamic hemorrhage].

A 73-year-old man was admitted complaining of violent involuntary movement in the left upper and lower extremities. He had a ten-year history of hypertension and had had a left thalamic hemorrhage 6 years before admission. On neurological examination Horner's sign in the right eye, typical hemiballism in the left extremities and right hemiparesis, which was caused by the previous left thalamic hemorrhage, were observed. CT scan and MRI revealed recent hemorrhage in the right subthalamic nucleus. Haloperidol, tiapride and diazepam were administered to ameliorate the ballism, but they had to be reduced in amount because of the development of parkinsonism. Two months after onset, when there was still moderate ballism, he suffocated due to a swallowing disturbance. After two hours' coma, consciousness returned gradually. Twenty-four hours after suffocation, the neurological examination revealed normal consciousness and no deterioration in other neurological symptoms, but the ballism had almost disappeared without medication. No change was detected in MRI findings and the blood flows in the basal ganglia before and after suffocation. It is interesting that transient hypoxia due to suffocation reduced hemiballism in this patient without neuroradiological findings of ischemia in the basal ganglia. The mechanisms of reduction of hemiballism after transient hypoxia were discussed.