In 1895, Hill and Bernard postulated that a failure of splanchnic vasoconstriction on assumption of the upright posture could lead to low blood pressure (BP) in man.1,2 The first description of patients with postural hypotension was reported by Bradbury and Eggleston3 in 1925. The clinical features in the patients these authors described included orthostatic hypotension, syncope, fixed heart rate, heat intolerance, anhidrosis, nocturnal polyuria, and impotence. This description is complete in view of our present understanding of this illness.
Table 1 provides a partial list of several conditions known to impair autonomic function; each of the disorders listed may disrupt afferent, efferent, or CNS components of the autonomic nervous system pathway. Secondary causes of autonomic failure include identifiable diseases of the sympathetic outflow; eg, in the CNS, these include brain tumors, parkinsonism, and cerebral infarction. In the spinal cord, lesions such as tabes dorsalis and syringomyelia must be