Studies of cerebral circulation time in man. 1. Normal values and alterations with cerebral vascular disease and tumour in arm-to-retina circulation times.

During an extensive arteriographic investigation of subjects with arteriosclerotic, atherosclerotic, and thrombotic cerebral vascular disease, considerable delay has often been observed in opacification of the small cerebral arteries (Meyer, Sheehan, and Bauer, 1960; Sheehan, Bauer, and Meyer, 1960; Bauer, Sheehan, and Meyer, 1961; Bauer, Sheehan, Wechsler, and Meyer, 1962). The delay in filling is probably due to slowing of the cerebral circulation and in some cases it has been necessary to delay exposure of radiographs for one to five seconds in order to obtain satisfactory visualization of the intracranial vessels. Such prolongation of the circulation time, demonstrated arteriographically, has now been confirmed in some of our cases of cerebral vascular disease by the use of the SanchezPerez serial casette changer and a timing device. Slowing of the cerebral circulation time has also been shown following experimental cerebral embolism or occlusion of the middle cerebral artery (Meyer, 1958; Meyer, Gotoh, and Tazaki, 1962). Such observations led us to the hypothesis that simple bedside measurement of the arm-to-retina circulation times might be a valuable, although indirect, method of evaluating slowed cerebral circulation in embolic, thrombotic, arteriosclerotic, and atherosclerotic cerebral vascular disease. The arm-to-retina circulation time has been evaluated previously in the diagnosis of carotid artery occlusion by comparison of the circulation times of the two sides (David, Saito, and Heyman, 1961; Hollenhorst and Kearns, 1961; Heyman, 1961) but not in other forms of cerebral vascular disease. Theoretically, arm-to-retina circulation times should vary with cardiac output, systemic vascular resistance, cerebral vascular resistance, vascular resistance of the external carotid circulation, retinal