Production of subcortical lesions by implantation of radioactive substances.

Abstract

Stereotaxic implantation of Pd109 and Y90 spheres in subcortical structures in the brains of cats showed that these pure sources of BETA radiation can be relied upon to produce histologically standardized lesions. Max lesion volume is dependent upon the energy of the BETA rays emitted, and variation of source strengih permits adjustment of the diameter of the resultant radionecrosis. Two weeks after implantation the spheres were surrounded by a zone of cytological change and there was an irregular transition from dead. to damaged, and normal cells. Beyond this was a ring of edema. Although stereotaac placement of a sphere of this strength in the area produced a lesion, none of the metabolic changes previously caused by electrocoagulation of the area developed, and the animals remained healthy until killed 3 weeks after operation. The difference obtained with the radionecrotic method is accounted for on the basis that the lesions are discrete and gradual in development. Clinical trial of this method was undertaken in which 2 Y90 sources, each approximates 400 mC in strength, were implanted in the globus pallidus of individuals with parkinsonism The resultant clinical improvement indicated that quantitated radionecrosis might have a place in stereotaxic neurosurgery. A stereotaxic manipulator,more » constructed for delivery of sources of BETA radiation and so shielded as to hold the radiation exposure of the operating personnel at negligible levels, is described. (H.H.D.)« less