Generalized hyperalgesia in women with endometriosis and its resolution following a successful surgery

Although pains of various kinds top the list of complaints from women with endometriosis and are the most debilitating of the disease, little is known about the mechanism/mechanisms of endometriosis-associated pains. To test the hypothesis that women with endometriosis have generalized hyperalgesia which may be alleviated by a successful surgery, we recruited 100 patients with surgically and histologically confirmed endometriosis and 70 women without, and tested their responses to pain stimulations. Before the surgery, all patients rated their dysmenorrhea severity by Visual Analog scale (VAS) and went through an ischemic pain test (IPT) and an electrical pain test (EPT). The controls were also administrated with IPT/EPT. Three and 6 months after surgery, all patients were administrated with IPT/EPT and rated their severity of dysmenorrhea. We found that patients with endometriosis had significantly higher IPT VAS scores and lower EPT pain threshold than controls, but after surgery their IPT scores and EPT pain threshold were significantly and progressively improved, along with their dysmenorrhea severity. Thus, we conclude that women with endometriosis have generalized hyperalgesia, which was alleviated by surgery. Consequently, central sensitization may be a possible mechanism underlying various forms of pain associated with endometriosis, and its recognition should have important implications for the development of novel therapeutics and better clinical management of endometriosis.