Case Report Successful Treatment of Lower Limb Complex Regional Pain Syndrome following Three Weeks of Hyperbaric Oxygen Therapy Rita Katznelson, 1,2 Shira C. Segal, 1 and Hance Clarke 1 1 Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada M5G 2C4 2 Division of Hyperbaric Medicine, Toronto General Hospital, Toronto, ON, Canada M5G 2C4 Correspondence should be addressed to Rita Katznelson; rita.katznelson@uhn.ca Received 22 October 2015; Accepted 8 December 2015 Copyright © 2016 Rita Katznelson et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Hyperbaric oxygen therapy (HBOT) is a treatment that delivers 100% oxygen at increased atmospheric pressures. e efficacy of HBOT for treating pain has been described in various animal pain models and may have clinical efficacy in the treatment of human chronic pain syndromes. We present our experience with posttraumatic Complex Regional Pain Syndrome (CRPS) type 2 in a patient who underwent 15 sessions of HBOT. A 41-year-old male with one-year history of CRPS of leſt foot followed by leſt ankle fracture demonstrated less pain, decreased swelling, less allodynia, and improvement in skin color and range of motion of the lower limb aſter 3 weeks of HBOT. Patient was back to work for the first time in over a year. HBOT may be considered as a valuable therapeutic tool in the treatment of long-standing CRPS. 1. Introduction Mechanisms of Complex Regional Pain Syndrome (CRPS) are poorly understood. Tissue hypoxia and inflammation can play an important role in the pathophysiology of this potentially debilitating condition [1–3]. We present the case of patient (G.G.) with CRPS type 2 of his lower leg that responded to a 3-week course of hyperbaric oxygen therapy. On February 21, 2014, G.G. slipped on ice in a parking lot while leaving work for the day and sustained a Weber B leſt ankle fracture. On February 23, 2014, he underwent an open reduction internal fixation of his ankle. His postoperative course was complicated with a cellulitis infection treated with antibiotics. Intense acute pain developed in his left ankle and foot immediately aſter the injury and the pain was very difficult to control postoperatively. G.G. developed persistent pain, which he described as having intermittent shooting qualities and severe electric shock episodes. It was accompanied with swelling, skin discoloration, allodynia, and temperature changes leading to diagnosis of CRPS of the leſt foot in April 2014. e computed tomography of the leſt ankle 6 months aſter surgery demonstrated union of the lateral malleolar fracture. Ultrasound of the leſt ankle at the same time was unremarkable. e patient was engaged in a rehabilitation program that focused on pain management, desensitization techniques, range of motion exercises, balance, gait retraining, and endurance training. G.G. was under the care of a chronic pain physician and his medication regimen included pregabalin 75 mg twice daily, acetaminophen and NSAIDs as needed, multivitamins, calcium, magnesium, and glucosamine. He experienced some relief in his symptoms by December 2014. Approximately 1 year following his ankle injury, on February 5, 2015, G.G. underwent removal of his plateau in an attempt to alleviate his pain. Unfortunately, his symptoms such as pain, swelling, and allodynia intensified and he presented to our clinic with hopes that hyperbaric oxygen therapy (HBOT) could potentially improve his symptoms. On March 17, 2015 (13 months since initial injury, 6 weeks since last surgery), prior to commencing HBOT, G.G. complained of a constant, dull, aching pain with intermittent shooting sensations. His numeric rating scale (NRS) pain score was 7-8/10 at its worst and 6/10 on average. Walking, standing, and sitting exacerbated the pain, and the pain Hindawi Publishing Corporation Pain Research and Management Volume 2016, Article ID 3458371, 4 pages http://dx.doi.org/10.1155/2016/3458371