CHANGES in cerebral blood flow induce changes in the cerebrospinal fluid pressure in the same direction.1 This report presents evidence that changes in craniospinal blood volume modify the extent of this effect.
MATERIALS AND METHODS
The types of patients studied and the methods of continuously recording the several pressures of interest have been described.2 The patients included in this report were all those who had pressure-volume curves determined3 and had satisfactory recordings of the arterial pressures.
OBSERVATIONS
We have shown from the drug responses that variations in cerebrospinal fluid pressure associated with variations in arterial pressure are due not to changes in arterial or systemic venous pressure but to concomitant changes in cerebral blood flow.1 The fluid pulses associated with systole and diastole, the "arterial" pulses, are due, therefore, to pulsatile changes in flow rather than to the measured variations in arterial pressure. It has been