A model for radiating leg pain of endometriosis.

Endometriosis is a prevalent female health disorder that often leads to back pain and radiating leg pain. Patients with such pain often seek care from multiple health care professionals, including manual therapists. We hypothesized that endometrioma can induce nerve inflammation thus the radiating leg pain that often accompanies endometriosis. To model sciatic endometriosis in female Wistar rats, a section of uterine horn was autotransplanted to the sciatic nerve. Uterus sections with the endometrium removed and autotransplanted to the sciatic nerve served as controls. After 1, 3, and 15 months the nerves were harvested and processed for immune cell presence and for neural elements. Control nerves were harvested after 4 months. All autotransplants survived, resulting in a fusion of the uterus sections to the nerves. Macroscopically, turgid cysts apposed to the nerves characterized the complexes. Microscopically, the complexes contained recruited macrophages, indicating persistent inflammation, and were innervated by small diameter axons. Only 1 of 8 control rats developed a small cyst, presumably due to residual endometrium. The persistent immune response and innervation suggest the nerve-uterus complexes as sources of inflammation and persistent neural discharge, and thus pain. This model could shed light upon the radiating leg pain that often accompanies endometriosis. Manual therapists should be aware of the possibility of endometriosis causing symptoms and examination findings that mimic musculoskeletal etiologies.