Acute hydrocephalus was induced in five monkeys. Continuous recordings of Ventricular fluid pressure, respirations, and systemic arterial and venous pressures were performed for one hour before and 24 hours after ventricular obstruction. Ventricular fluid pressure was labile, increasing and decreasing over short time periods. During the increasing phase, two patterns of wave form emerged: "undulating" waves associated with periodic respirations and "monophasic" waves with hyperpnea. The latter occurred at higher levels of pressure and represent more ominous development. Concomitant changes occurred in systemic arterial pressure. Undulations in systemic arterial pressure were associated with undulating ventricular waves, the same as Mayer waves. Ventricular waves closely resemble the one-per-minute and plateau waves recorded in humans. Caudal displacement of the brain stem (four monkeys) is believed to be the result of generalized hydrocephalus and increased intracranial pressure.
Obenchain TG, Stern WE. Continuous Pressure Monitoring in Experimental Obstructive Hydrocephalus: I. The Dynamics of Acute Ventricular Obstruction. Arch Neurol. 1973;29(5):287–294. doi:10.1001/archneur.1973.00490290027001
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