Sympathotonic orthostatic hypotension: a report of four cases.

We describe four patients with sympathotonic orthostatic hypotension, a syndrome in which the decrease in blood pressure associated with standing is accompanied by tachycardia. The patients in this series had experienced either a viral infection or rapid weight loss prior to the onset of their orthostatic intolerance. Vasomotor reflexes and norepinephrine production were normal, and analysis of palmar autonomic surface potentials indicated that the sympathetic innervation of the upper extremities was intact. The amplitudes of the plantar autonomic surface potentials, however, were decreased although still within the normal range. The latencies of plantar autonomic surface potentials were slightly prolonged. Although most autonomic function tests are normal in sympathotonic orthostatic hypotension, mild abnormalities in the plantar autonomic surface potentials may indicate a neuropathy that primarily affects low thoracic or lumbar sympathetic neurons.