L-dopa-resistant parkinsonism syndrome following cerebral radiation therapy for neoplasm

A bradykinetic form of parkinsonism, unresponsive to levo-dopa therapy deve loped in four patients two to eight weeks after completion of external beam irradiation (39.2 Gy to 59.4 Gy) of their intracranial neoplasm. In the ab sence of other causative factors, we relate the movement disorder to radiat ion-induced changes within the basal ganglia. At post mortem examination on e patient had putamenal gliosis and thickened vessels with loss of nigral n eurons.