Local and central orthostatic sympathetic reflexes in Raynaud's phenomenon.

Finger and hand blood flow was measured by 133xenon washout technique during orthostatic manoeuvres in patients with primary Raynaud's phenomenon (PR), Raynaud's phenomenon secondary to generalized scleroderma (GS) and in healthy, cold-tolerant controls. When supine, finger and hand washout rates in PR were significantly elevated over that of controls and GS. A significantly decreased response to a 40-cm lowering of the hand (local vasoconstrictor response) was observed in PR and was found to be normal in GS. During head-up tilting to 45 degrees (central sympathetic stimulation), all three groups showed parallel responses. We conclude that no increased responses on local or central orthostatic sympathetic reflexes were seen in patients with Raynaud's phenomena. A generally increased sympathetic activity as pathophysiological background for the vasospastic attacks is not likely. However, the increased finger 'blood flow' observed in patients with primary Raynaud's phenomenon in the resting condition, which we interpret as a 'hyperaemic' state, might have influenced the orthostatic sympathetic responses.