Idiopathic orthostatic hypotension from failure of noradrenaline release in a patient with vasomotor innervation

Abstract

A 26 year old man is described with life long orthostatic hypotension unrelated to autonomic nerve degeneration and apparently due to failure of peripheral noradrenaline release. Tests of parasympathetic and sympathetic cholinergic nerve function were normal, but sympathetic adrenergic activity was defective. Thus blood pressure regulation was abnormal. There was no pressor response to tyramine, an indirect sympathomimetic drug, but a marked pressor response to the directly acting sympathomimetic drugs phenylephrine and noradrenaline. On standing there was a progressive fall rather than a rise in circulating noradrenaline concentrations, although adrenaline levels rose normally. The pupils showed diminished responses to ephedrine and cocaine, and a normal response to phenylephrine. Fluorescence microscopy of blood vessels showed that they were innervated with adrenergic nerves. His orthostatic hypotension responded well to oral phenylephrine (50 mg five times daily) but not to other forms of therapy. It is suggested that this patient's symptoms were due to failure of noradrenaline release even though sympathetic adrenergic nerves were present. We therefore wish to draw attention to a further cause of orthostatic hypotension, failure of peripheral noradrenaline release without autonomic neuropathy.