Treatment of Complex Regional Pain Syndrome (CRPS) Using Low Dose Naltrexone (LDN)
A 48 year-old male veteran sustained an injury to his right leg in 2006. While undergoing aqua-therapy, he injured his right great toe, which subsequently became infected. Following drainage of an abscess and removal of the great toe’s nail, the patient developed the following CRPS symptoms in his right lower extremity: swelling, allodynia (pain to normal touch), color change, temperature change, and some weakness. By 2007, the patient developed moderate CRPS symptoms in his upper extremities. In 2008, he developed blisters and skin ulceration in his right lower extremity (Fig. ). At this time, the patient was being treated with opioids, pregabalin, and duloxetine.\nBy 2009, the patient’s pain had become severe enough that he could not ambulate without assistance. He developed muscle spasms in the right upper extremity. In 2010, he underwent a cardiac bypass surgery for coronary artery disease. His CRPS symptoms became widespread after this surgery, spreading to his upper chest, upper arms, and forearms. In 2011, the patient developed significant dystonic spasms to both upper extremities, resulting in hyperextension of his fingers. From 2008 to 2012, the patient underwent multiple treatments with anticonvulsants, antidepressants, physical therapy, psychotherapy, topical and systemic analgesics, including but not limited to opioids. The patient also currently has diabetes mellitus type II, hypertension, hyperlipidemia, as well as coronary artery disease.\nIn August of 2011, the patient began low-dose intravenous ketamine infusions. He reported a good initial response, but the relief was not sustained. He continued to have ketamine booster infusions at intervals of 4 to 6 weeks. Although the patient engaged in aggressive physical therapy during this time, his maximum interval of relief from pain following a given ketamine infusion decreased to an interval of 3 weeks. In January 2012, his use of the opioid oxycodone was changed to tapentadol. This narcotic was removed for 1 week prior to starting low-dose naltrexone, which was started and maintained at 4.5 mg per day (1 dose at night). Additional medications included: metformin, tramadol, valsartan, cloazepate, simvastatin, fish oil, and vitamin C.\nImmediately before LDN treatment, the patient had patchy areas of allodynia to the medial and dorsal aspect of his right foot, extensive areas of dysesthesia in his right lower extremity below the knee and heel of his foot, as well as bilaterally dysesthesia in the upper extremities. There were significant color and temperature changes in the right foot compared to the left foot, as well as pitting edema in the right foot. A triple-phase bone scan revealed significant reuptake in the right foot, characteristic of CRPS.\nBy March of 2012, the patient’s requirements for the lower dose intravenous ketamine infusions were not as frequent (6 week intervals, pain spikes not as high). The patient recovered from CRPS flares more quickly, felt more energetic, and tolerated pain better. He became physically more active, and his sleep improved significantly. Within 2 months after starting LDN, the patient’s dystonic spasms discontinued, although he still had moderate pain in both upper extremities. The patient was able to walk without a cane (Fig. ), which he had used continuously since 2006. His pain was an average of 8 to 10 on the Numeric Rating Scale (NRS) before starting LDN. It dropped down to an average of 5 to 6 on the NRS after starting LDN. After LDN therapy, the patient’s pain symptoms have reduced in severity, but not in their distribution. His current mood state is good. No side effects of LDN were noted.