The Effect of Increased Infratentorial Intracranial Pressure and the Elevation of Blood Pressure on Frontal Cortical, Pontine Cerebral Blood Flow and Auditory Evoked Potentials

ABSTRACT

Patients with extra-axial mass lesions of the posterior fossa frequently demonstrate signs of brainstem dysfunction. These dysfunctions may be induced by the change of regional cerebral blood flow and electrophysiological status as well as mechanical compression and distortion of the brainstem. Frontal cortical regional cerebral blood flow(rCBF), pontine rCBF, brainstem autidory evoked potentials(AEPs), infratentorial intracranial pressure(infratentorial ICP) and mean arterial blood pressure(MABP) were recorded before and after expansion of an infratentorial epidural ballon in anesthetized experimental cat models. After the elevation of MABP during the increased infratentorial ICP, frontal cortical and potine rCBF, AEPs were recorded every 30 minutes. The results suggest that the elevating the MABP to improve cerebral perfusion pressure before irreversible change occurs in the brain may preserve cerebral function. We conclude that if the volume of the space in the posterior fossa that is occupied by the mass can be estimated, brain damage from low rCBF and brain compression due to intracranial hypertension can be prevented by the elevation of MABP before irreversible damage of the brain occurs.