Supratentorial pressures. Part II: Intracerebral pulse waves.

Intracerebral pulse waves were recorded in cat and monkey while intracranial pressure (ICP) manipulations were performed. The intracerebral pulse waves appeared comparable to cerebrospinal fluid (CSF) pulsations. The wave forms were divided into multiple smaller waves, designated P1 to P4. The P1 component was primarily of arterial origin and was accentuated by increasing ICP unrelated to increased venous pressure, most commonly from a mass lesion. Bilateral carotid occlusion resulted in decreased amplitude of P1. Venous hypertension from jugular venous or sagittal sinus occlusion, on the other hand, accentuated waves P2 and P3 more than P1. This is consistent with a Starling resistor model of the cerebral venous system in which mass lesions may compress low-pressure veins and accentuate the arterial pressure-dependent P1 wave, whereas venous hypertension causes increased prominence of the later P2 and P3 waves.