[Analysis of intracranial pressure pulse wave in experimental hydrocephalus]

Much has been written about the relationship between the pulse pressure (PP) of the intracranial pressure pulse wave (ICPPW) and ventricular dilatation. Some data suggest that high PP is the cause of ventricular dilatation, and other authors have reported that high amplitude of PP results from decreased intracranial compliance. In order to clarify these points, the amplitude of PP and Pressure-Volume Response (PVR: an indicator of intracranial compliance) were measured in bilateral ventricles using Howchwald's hydrocephalic model (right-left difference in ventricle size is clear, due to hemicraniectomy).

Hydrocephalus was developed by means of intracisternal injection of a Kaolin powder solution using dogs. The mean ICP, amplitude of the PP, PVR and ventricular size (studied by MR image) were evaluated under pathological conditions induced by the following procedures. Group A: control. Kolin induced hydrocephalus without craniectomy. Group B: Kaolin induced hydrocephalus with right side craniectomy. Group C: Kaolin induced hydrocephalus with right side craniectomy and dural resection. Group D: Kaolin induced hydrocephalus with right side craniectomy, dural resection and temporal muscle resection.

Using MR imaging, the same degree of symmetrical ventricle dilatation were identified in all groups except Group D. Group D alone demonstrated the difference of ventricular size (craniectomy side > non craniectomy side). There was no appreciable difference in mean ICP between each group. However the amplitude of PP and the PVR decreased stepwise from Group A to Group D. The difference of the amplitude of the PP and PVR between the right and left ventricles in each group was not significant. Even in the larger ventricle side (right) of Group D, the amplitude of PP was same as that of the left ventricle, and much smaller than that of other groups.

The results of our research suggest that: 1) There was no relation between the ventricular dilatation and the amplitude of PP. This means that the increased amplitude of PP was not the cause of the ventricular dilatation in this model. 2) These evidences suggest that a high degree of correlation exists between the amplitude of PP and the PVR. This means that PP can be a good parameter of the intracranial compliance in this model.