A patient, 11 year old boy, is described with a occulsion of the circle of willis developed three months after the removal of cerebellar astrocytoma. Pre-and postoperative angiograms show ed no abnormal vasculature in the supratentrial region except internal hydrocephalus. Several attacks of transient hemiparesis were initiated two months postoperatively. Generalized convulsion followed with right side hemiplegia and with motor aphsia was noticed three months after the operation. Four vessel angiograms revealed typical patterns of the occulsion of the circle of Willis when these symptomes were prominent. Authors concluded that abnormal vascular network was the collateral pathway secondarily due to the occulsion of the circle of Willis. It is suggested that the cause of vascular occulsion may not correlate with cerebellar tumor.
