endothelin-1 and Complex-Regional-Pain-Syndromes

The clinical characteristics of complex regional pain syndrome (CRPS)--spontaneous and stimulus-evoked pain, autonomic abnormalities, motor dysfunction, and trophic changes in the affected limb--are well known. However, its pathogenesis is unclear, and the diagnosis is often delayed, in part due to lack of objective laboratory tests. Endothelin-1 (ET-1) is a potent vasoconstrictor that has recently been shown to produce pain, allodynia, edema, and muscle weakness, as well as to exert a direct excitatory effect on nociceptive afferents. Furthermore, new evidence indicates that ET-1 is involved in various cancer- and non-cancer-related painful conditions. The aim of the present explorative study was to determine the ET-1 plasma levels in patients with CRPS in an attempt to identify a 'laboratory marker' for CRPS and to search for evidence suggesting that ET-1 may be involved in the pathogenesis of CRPS. ET-1 plasma levels were determined in 20 severely affected CRPS patients, in eight patients with non-CRPS chronic painful conditions, and in 10 healthy volunteers. The results showed that there were no significant differences in ET-1 plasma levels between the three groups. We conclude that the plasma level of ET-1 cannot be regarded as a 'marker' for CRPS. Yet, the possibility that ET-1 is involved in the pathophysiology of CRPS has not been excluded and deserves further investigation.

Topics: Adult; Complex Regional Pain Syndromes; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Functional Laterality; Humans; Male; Pain Measurement; Pain Threshold; Surveys and Questionnaires

Impaired microcirculation during the chronic stage of complex regional pain syndrome (CRPS) is related to increased vasoconstriction, tissue hypoxia, and metabolic tissue acidosis in the affected limb. Endothelial dysfunction is suggested to be the main cause of diminished blood flow. The aim of this study was to examine the distribution of endothelial nitric oxide synthase (eNOS) and endothelin-1(ET-1) relative to vascular density represented by the endothelial marker CD31-immunoreactivity in the skin tissue of patients with chronic CRPS.. We performed immunohistochemical staining on sections of skin specimens obtained from the amputated limbs (one arm and one leg) of two patients with CRPS.. In comparison to proximal specimens we found an increased number of migrated endothelial cells as well as an increase of eNOS activity in distal dermis specimens.. We found indications that endothelial dysfunction plays a role in chronic CRPS.

Topics: Adult; Amputation, Surgical; Chronic Disease; Complex Regional Pain Syndromes; Endothelin-1; Extremities; Female; Humans; Immunohistochemistry; Middle Aged; Nitric Oxide Synthase Type III; Platelet Endothelial Cell Adhesion Molecule-1; Skin