Two Cases of Postural Hypotension Showing

Of the two forms of orthostatic hypotension, one, the arterial orthostatic anemia or hypotonic regulatory disturbance (1), is characterized by an increase in the pulse rate and a fall of the systolic blood pressure, with or without a rise in the diastolic pressure, upon change from the recumbent to the erect posture. These circulatory reactions are due to an increased activity of the sympathetic nervous system, which normally compensates for the hydrostatic displacement of blood due to the changes in position. In the second form, the postural hypotension or hypodynamic regulatory disturbance, this reaction of the sympathetic system to changes in posture is absent. The result is a momentary fall of the systolic as well as the diastolic blood pressure during a change from the recumbent to the erect posture, the pulse rate being maintained at a constant level (Figure 1). Postural hypotension was described for the first time in 1925 by Bradbury and Eggleston (2). It is a rather rare condition, of which Springarn and Hitzig (3), in 1942, found only 50 cases described in the literature. It is supposed to be due to organic lesions in the brain stem or spinal cord, following encephalitis, encephalomalacia and tumors, tabes dorsalis, syringomyelia and hematomyelia (4-6). A similar condition may also occur after extensive sympathectomies (7-9). Hammarstrom and Lindgren (10) made histological studies of the central nervous system in a case of postural hypotension and found lesions located in the right internal capsule, the cerebellum, the occipital lobes, and the cortex of the lateral parts of the hemispheres of the cerebrum. In the present study of two cases of postural hypotension, the authors determined the daily urinary excretion of the catechol amines, epinephrine and nor-epinephrine. The urinary output of epinephrine after intravenous administration of insulin, which increases the output by ten-fold in healthy subjects (11), was also studied. In one of the cases, the urinary excretion of catechol amines was followed during an intravenous infusion of norepinephrine, as well as after a subcutaneous injection of histamine.