Clinical Investigations on Interrelations Between Intracranial Pressure and Intracranial Hemodynamics

Abstract

Studies of the ventricular fluid pressure (VFP) by continuous recording have shown that, in patients with intracranial hypertension the VFP has a marked tendency to rapid variations and that these variations often follow certain well defined patterns. It has been possible to distinguish three main forms of variations. Two are of a rhythmic nature and related to periodic breathing of the Cheyne-Stokes' type and to Traube- Hering-Mayer waves of the systemic blood pressure. They are probably related to an intrinsic rhythmic acitivity of medullary centers, released from influence of higher centra in the upper brain stem and may serve as examples of variations of the VFP caused by variations of the blood pressure within the cerebral vascular bed. A less known cause of increase in intracranial pressure is augmentation of the functional activity of the brain. By continuous recording via a lumbar needle Haug found that mental stimuli and pain provoked elevations of the CSF pressure. A decrease in CBF during spontaneous plateau waves has been shown by the isotope clearance technique and by the thermo—electric technique of Hensel and Betz. The rise in intra-cranial pressure causes a decrease in CBF followed by hypoxia and that the vasodilatation is due to the local action of hypoxic metabolites. The latter explanation would be in accordance with the increasing evidence that the autoregulation of the CBF is mainly governed by the cerebral metabolism.