Complex Regional Pain Syndrome (“CRPS”), formerly known as Reflex Sympathetic Dystrophy (“RSD”), is a chronic, painful, and disabling progressive disorder of the sympathetic nervous system. It affects one or more extremities, and most often occurs following trauma, such as a fracture or nerve damage to the affected extremity. CRPS is characterized by excruciating pain that is disproportionate to the original injury, which continues long after the original injury has healed. See id. Additionally, CRPS causes vasomotor (relating to the constriction and dilation of blood vessels), sudomotor (stimulation of sweat glands), inflammation, motor impairment, hyperesthesia, trophic changes (changes brought about in tissues from interruption or destruction of nerve, blood supply or both), and allodynia (a painful response to a normally innocuous stimulus such as a touch, sound, temperature, or vibration) in the affected extremity. See id.
Pain is a subjective experience. This recognition led to the development of the McGill Pain Scale, which is widely used around the world to help health care professionals gauge their patients’ level of pain. See id. “A CRPS pain flare is the most intense pain known to man and ranked the highest on the McGill pain scale, scoring higher than amputation and childbirth.” Id. Many that are diagnosed with CRPS commit suicide due to inability to tolerate the excruciating pain and inability to cope with the severe functional limitations. The Reflex Sympathetic Dystrophy Syndrome Association (“RSDSA”), a non-profit organization dedicated to providing support and education, while driving research to find effective treatments and a cure for CRPS, compared living with CRPS as equivalent to “living with chronic pain more severe than a constant jellyfish sting” and constant electrocution from “sitting in an electric chair with bolts of electricity running through the [affected extremity].”
There is no cure  but various medical procedures can be used to reduce pain such as Stellate Ganglion Blocks.
Many suffering from CRPS will experience “unremitting pain and crippling, irreversible changes in spite of treatment.” Id. No single drug or combination has produced consistent long-lasting improvement in symptoms. See id. CRPS pain “is severe and unresponsive to almost all analgesics.” “Opioids will not control the pain of a flare-up unless given in a quantity that would make the patient somnolent.” Therefore, “[o]pioids are not considered as first-line treatments for patients suffering from CRPS.” Id. “Because there is no cure for CRPS, treatment [such as physical therapy] is aimed at relieving painful symptoms.”
 See Colleen M. Johnston, Florin I. Oprescu & Marion Gray, Building the Evidence for CRPS Research from a Lived Experience Perspective, 9 Scandinavian Journal of Pain 30, 31 (2015).
 See RSDA Information Package, The Reflex Sympathetic Dystrophy Syndrome Association, (May 18, 2016), http://rsds.org/wp-content/uploads/2016/03/RSDSA-Information-Package-3-31-16.pdf; see also Audrey Johns, The Taste & CRPS: The Story of a Brave Pain Warrior, 1 The Reflex Sympathetic Dystrophy Syndrome Association Newsletter, 2 (2014), http://rsds.wpengine.com/wp-content/uploads/2015/02/RSDSA_NEWSLETTER_ISSUE_2_R9.pdf.
 See Complex Regional Pain Syndrome Information Sheet, National Institute of Neurological Disorders and Stroke, (Nov. 3, 2015), http:// www.ninds.nih.gov/disorders/reflex_sympathetic_dystrophy/reflex_sympathetic_dystrophy.htm.
 See RSDA Information Package, The Reflex Sympathetic Dystrophy Syndrome Association, (May 18, 2016), http://rsds.org/wp-content/uploads/2016/03/RSDSA-Information-Package-3-31-16.pdf.
 See Im Ducharme, M.D., C.M., F.R.C.P., Tips for Managing Complex Regional Pain Syndrome, Reflex Sympathetic Dystrophy Syndrome Association, (Sept. 11, 2015), http://rsds.org/wp-content/uploads/2016/03/RSDSA-Pediatric-Information-Package-03-30-16.pdf.
 See Complex Regional Pain Syndrome Information Sheet, National Institute of Neurological Disorders and Stroke, http:// www.ninds.nih.gov/disorders/reflex_sympathetic_dystrophy/reflex_sympathetic_dystrophy.htm.