Regional cerebral blood flow in delayed brain swelling following x-irradiation of the right occipital lobe in the monkey.

Four to 5 months after exposure of the right occipital lobe of the monkey to 3500 rads of X-irradiation there is a proliferative and degenerative lesion accompanied by a massive break in the blood-brain barrier. The resulting vasogenic edema causes gross swelling in the ipsilateral hemisphere, compression of the contralateral hemisphere with ventricular dilatation, and distortion of midline structures, which may result in herniation through the incisura and foramen magnum. The regional cerebral blood flow, determined by [14C]antipyrine method, at successive stages in the development and resolution of the delayed brain swelling shows a reduction of blood flow in white and gray matter, first regionally, then throughout the ipsilateral hemisphere and finally throughout the brain. This is accompanied by an increase in CSF pressure, CSF lactic dehydrogenase and total protein, and clinical signs of increased intracranial pressure. With resolution of CSF pressure, there is a return to baseline of CSF chemistry and partial resolution of the other parameters. The cerebral blood flow shows a greater recovery in gray than white matter, but there remains a diffuse depression suggesting a long-term impairment in cellular metabolism and/or blood flow regulatory mechanisms.