Changes in intracranial pressure (ICP) pulse wave following hydrocephalus.

The pulse pressure (PP) of the intracranial pressure pulse wave (ICPPW) was measured in experimental and clinical hydrocephalus: namely, obstructive and kaolin-induced hydrocephalus as an experimental study, and noncommunicating and communicating hydrocephalus as a clinical study. At approximately the same ICP level, the PP was much higher in the obstructive hydrocephalus group and slightly higher in the kaolin-induced hydrocephalus group than in the controls. Also the PP level in noncommunicating hydrocephalus patients [3.19 mm Hg (SD: 1.04)] was significantly (P less than 0.05) higher than that in the communicating hydrocephalus patients [1.88 mm Hg (SD: 0.60)]. The results of our research suggest that the stronger the disturbance of the communication of the CSF between cranial cavity and spinal cavity the higher the PP of ICPPW. This results from the distensibility of the spinal dural sac and exerts a great influence on the elasticity and the PP of the cranial system. It is reasonable, therefore, to suggest that a marked increase in the ratio of the PP to the ICP in the normal or slightly high ICP hydrocephalus may indicate disturbance of the CSF flow, especially loss of CSF communication between the cranial and spinal compartments.