[Response of the ventricular system of the brain to anti-orthostasis and occlusion of the jugular veins].

Twenty test subjects were subdivided into two groups with respect to the reactions of brain ventricles to a preliminary head-down test (-30 degrees). Group 1 consisted of subjects who showed ventricular enlargement, headache and nausea; Group 2 included subjects without these reactions. The test subjects were also exposed to tests with neck vein occlusion. The first (continuous) test was performed at +40 mm Hg for 5 min; the second (step) test was carried out from +10 to +50 mm Hg for 2 min at each step. The results obtained demonstrate that an inadequate venous outflow from the cranial cavity influences brain ventricles; the data also give evidence that changes in compensatory mechanisms can be detected using occlusion tests.