Effect of Changes in Systemic Venous Pressure on Cerebrospinal Fluid Pressure

THE RELATION between the cerebrospinal fluid pressure and the pressure in the internal jugular veins and in the intracranial venous sinuses has been studied by Becht, 1 Weed and Flexner, 2 and Bedford. 3 In substance, they found that the venous pressure was not modified essentially by changes in cerebrospinal fluid pressure, but that the fluid pressure was modified to some extent by changes in the venous pressure. None of them reported the effects of concomitant changes in both variables. We are presenting such observations because of their theoretical importance in a study of the factors controlling the cerebrospinal fluid pressure. MATERIALS AND METHODS The types of patients studied and the methods of continuously recording the several pressures of interest have been described. 4 OBSERVATIONS The Valsalva procedure shows how dependent the cerebrospinal fluid pressure is on the systemic venous pressure. When the Valsalva experiment is performed at initial fluid