Q How have new understandings about the pain mechanisms involved with endometriosis-caused pelvic pain improved treatment?
According to Dr. Rapkin, the increased understanding of the mechanisms involved in endometriosis-associated pain gained from these key studies led to a paradigm shift, with endometriosis being viewed not just as a condition with mechanical hypersensitivity due to altered anatomy and inflammation but also as a neurologic condition, or a nerve pain condition with peripheral and central sensitization. “This means there is upregulation or hyperactivity both in the periphery (in the pelvis) and centrally (in the spinal cord and brain),” said Dr. Rapkin.
“In the periphery, the endometriotic lesions develop an afferent sensory innervation and communicate with the brain. Stimulation of these nerves by the inflammatory milieu contributes to pain.” Dr. Rapkin noted research by Maria Adele Giamberardino, which demonstrated that women with endometriosis and pain have a lower threshold for feeling pain in the tissues overlying the pelvis (the abdominal wall and back).14 This also has been shown by Dr. Berkley in rodents given endometriosis.
“The muscles develop trigger points and tender hyperalgesic points as part of the sensitization process. In addition, distant sensitization develops—women with pelvic pain and endometriosis have a lower threshold for sensing experimental pain in areas outside the pelvis, for example the back, leg, or shoulder. These discoveries clearly reflect up regulation for pain processing in the central nervous system.”
Dr. Rapkin also pointed to research published in 2016 by Sawson As-Sanie, MD, MPH, that showed an association between endometriosis-associated pelvic pain and altered brain chemistry and function.16 “Dr. As-Sanie demonstrated a decrease in gray matter volume in key neural pain processing areas in the brain in women with pain with endometriosis. This was not found in women with endometriosis who did not have pain,” she said. “Altered connectivity in brain areas related to perception and inhibition of pain is important in maintaining pain. Dr. As-Sanie’s studies also found that these changes are correlated with anxiety, depression, and pain intensity in patients with endometriosis and chronic pain.”
Continue to: Q What are some newer treatment approaches to chronic pain with endometriosis?