Influence of Intracranial Components on Intracranial Pressure Pulse Wave

Abstract

The following studies were made in order to clarify whether the intracranial pressure pulse wave (ICPPW) varies according to the pathological changes at the same level of intracranial pressure (ICP). The mean ICP and the ICPPW [particularly the pulse pressure (PP), and the tangent (rising slope)] were examined in four groups of anesthetized dogs under artificial respiration; 1) cisternal saline injections (control), 2) hypercapnia induced, 3) acute hydrocephalus, 4) chronic hydrocephalus. The following results were obtained: (1) In the control group, the PP and the tangent rose linearly with ICP; (2) At the same ICP level, hypercapnia increased the PP to a level higher than that of the control group. This is due to the fact that hypercapnia produced a significant increase in dv (pulsatile change in cerebral blood volume); (3) At an ICP level, acute hydrocephalus increased the PP and the tangent to levels higher than those of the control group. This may have been caused by an increase in the intracranial liquor and the isolation from the spinal sac, which acts to modulate pressure. (4) At an ICP level, chronic hydrocephalus increased the PP to a level higher than that of the control group. This may have been caused by an increase of intracranial liquor. It is concluded that ICPPW is influenced not only by ICP but by intracranial pathological changes.