SYMPATHETIC VASOCONSTRICTOR REFLEX PATTERN IN PATIENTS WITH COMPLEX REGIONAL PAIN SYNDROME

Twenty patients suffering from complex regional pain syndrome (CRPS) a nd 21 healthy control subjects were examined to evaluate sympathetic r eflex vasoconstriction. The mean age of the 12 female and eight male p atients was 48.9 (21-72) years. At the time of investigation the media n duration of the disease was 8.5 weeks (2-70). Twenty-one healthy sub jects were investigated for control. Different maneuvers, such as the veno-arteriolar reflex (VAR), inspiratory gasp (IG), cold presser test (CP) and mental arithmetic (MA), were employed to induce vasoconstric tion while the cutaneous blood flow of the affected and the contralate ral limb was recorded. In addition, the skin temperature of both limbs was measured by infrared thermography. In 14 of 20 patients and in 14 of 21 control subjects vasoconstriction due to the provocation tests could be measured, while the remaining six patients and seven controls showed vasodilatation in at least one test, and by that they were exc luded from analysis of vasoconstrictor reflex pattern. After thermoreg ulatory adaptation skin temperature was not different between the affe cted and the unaffected limb. Sympathetic reflex vasoconstriction trig gered by MA which represents cortical generated, moderate vasoconstric tor stimulus, was significantly reduced on the affected limb (102.9% o f prestimulus period) when compared to the control limb (85.0%, P < 0. 002) or to controls (84.8%, P < 0.001). VAR (pure postganglionic), IG and CP (both spinal and supraspinal), representing stronger vasoconstr ictor stimuli, revealed no significant side to side difference of symp athetic vasoconstriction and no significant difference as compared to controls. In conclusion our findings prove impairment of sympathetic v asoconstrictor activity after central vasoconstrictor stimulation in C RPS, and possible mechanisms are discussed. (C) 1998 International Ass ociation for the Study of Pain. Published by Elsevier Science B.V.