The CSF pulse wave in hydrocephalus

Twenty-one dogs were rendered hydrocephalic by the intracisternal injection of kaolin. After various intervals between 1 and 44 days the animals were anesthetized for the measurement of arterial (lingual), ventricular, and sagittal sinus pressures. Following the recordings the animals were sacrificed by formalin infusion, the brains sectioned serially, and ventricular size measured. In general, the longer the period of incubation the larger the ventricles. There was no correlation between the degree of hydrocephalus and mean or pulsatile ventricular pressure. All animals with a pressure of less than 9 torr demonstrated non-linear transmission of the arterial wave into the CSF (which is the same as the pulse in the venous bed). All animals with a pressure greater than 12 torr had linear transmission of the wave. These findings in the hydrocephalic animals are the same as those found in nonhydrocephalic animals with similar pressures. It is concluded that the CSF pulse wave seen in hydrocephalic dogs is a result of how the cerebrovascular bed processes the cardiac pulse wave and is independent of the hydrocephalic process. There is no evidence that the pulse wave produces hydrocephalus.