Delayed Brain Swelling after X-Irradiation of the Visual Cortex in the Macaca Mulatta

Abstract

For the past ten years we have studied the effect of 3,500 rads of x-irradiation, in a single exposure, on the cerebral cortex of the young adult Macaca mulatta. The geometry of the exposure and the dosimetry of the absorption area was determined at Brookhaven National Laboratory, in conjunction with Arland L. Carsten. The irradiation site, since 1966, has been the right visual cortex. This permits a precise measurement of functional changes as expressed in the visual evoked response. Attention has been directed to the ultrastructural evidence for cellular changes in carbohydrate and protein metabolism within days of exposure and, by light microscopy, to alteration in the dendritic plexus within four to twelve weeks, and the proliferative and degenerative changes of radionecrosis in the exposed area four to five months following irradiation [1]. Long-term functional alterations have included unilateral, succeeded by bilateral depression of the evoked response and behavioral blindness. Long-term structural changes have included periodic brain swelling and retrograde transsynaptic degeneration within the visual system. The purpose of the current series is to more precisely delineate, in time and degree, the delayed brain swelling following exposure to ionizing irradiation.