The Effects of an Acute Reduction in Blood Pressure by Means of Differential Spinal Sympathetic Block on the Cerebral Circulation of Hypertensive Patients 1

Recent observations by this group on the cerebral circulation in hypertension (1) have yielded normal values for cerebral blood flow and cerebral oxygen consumption but a marked increase in cerebrovascular resistance. Since the nature of this excessive vascular tone is obscure, it was felt that studies of its behavior during an acute fall in blood pressure might be of interest. Such studies, furthermore, should be pertinent to the rationale of therapy designed to lower the blood pressure in hypertension, since a fall in blood pressure must necessarily be accom- panied by a comparable embarrassment of the cere- bral circulation except insofar as the high cere- brovascular tone were capable of compensatory re- laxation.