Regional Cerebral Blood Volume During Acute Transient Rises of the Intracranial Pressure (Plateau Waves)

T is a well-known fact that progressive intracranial hypertension during one stage of its development is characterized by intermittent, sometimes paroxysmal symptoms. Continuous recording of the ventricular fluid pressure (VFP) in patients with expanding intracranial lesions has shown that such intermittent symptoms coincide with acute temporary rises of the VFP level? 8 The corresponding VFP curve usually follows a specific pattern, characterized by a steep rise to a high level (60-100 mm Hg) and, following some minutes, an often equally steep fall. This gives the curve a plateau-like appearance (Figs. 1-3). The plateau waves have been subjected to extensive clinical studies? ~,13,~s-21 Variations of the VFP curve similar to plateau waves could be provoked by increasing the pressure in the ventricles at ventriculography or by exerting pressure on the region of a skull defect. It was inferred that an induced or spontaneous increase of the intracranial pressure may cause dilatation of cerebral vessels which in turn causes the intracranial pressure to rise further? s By means of simultaneous recording of the cerebral blood flow ~7 and the ventricular fluid pressure combined with cerebral angiography, it was shown that the plateau waves are accompanied by dilatation of cerebral arteries and, at the same time, a decrease of the cerebral blood flow? 9 These findings indicate that during the plateau waves there is an increase of the intracranial blood volume. In general, the studies quoted suggest that the plateau waves may appear indepen