Intracranial Pressure Gradients Caused by Experimental Cerebral Ischemia and Edema

To assess the development and resolution of ischemic cerebral edema and brain swelling, measurements of intracranial pressure (ICP) were made in cats after the transorbital occlusion of one middle cerebral artery. Measurement of ICP gradients was difficult: epidural, subdural and intraventricular catheters caused brain damage or failed to function; the accuracy of a miniature strain gauge could not be determined after implantation; and absolute values for intradural pressures could not be obtained with epidural devices. However, variable increases of ICP were recorded on the sides of occlusion from three cats, and were directly related to the severity of the neurological deficits. On the sides opposite occlusion ICP increased slightly or not at all. Several days after occlusion ICP decreased and gradients could not be demonstrated with certainty. Thus, measurements of ICP gradients can be used to assess ischemic cerebral edema and brain swelling, but the usefulness of such measurements is limited at present by methodological problems.