Low Dose Naltrexone Therapy for Complex Regional Pain Syndrome

Complex Regional Pain Syndrome (CRPS) is a rare and often debilitating chronic pain condition whereby individuals may experience extreme sensitivity, discoloration, and swelling of the affected area -- along with numerous other painful symptoms. There are currently a limited number of treatment options available to those suffering with the condition, with various treatments including nerve blocks, neuropathic medications, and desensitization physical therapy modules. There is budding interesting in the role naltrexone, an opiate antagonist, may play in the pain management of CRPS when prescribed in very low doses. This study aims to collect preliminary data on pain scores, symptom severity, and side-effects in patients with Complex Regional Pain Syndrome randomized to receive low dose naltrexone or placebo capsules. Enrollment of 40 patients total will occur over two years from study start to study end. Each patient will be randomized to receive placebo capsules or active low dose naltrexone capsules, with both the patient and treating clinician blind to the randomization. Each patient will be actively enrolled in the study for six months and will take the medication daily at the instructed dose for the respective duration of time. Following the initial visit and study enrollment, the investigators are asking each patient to return for three (3) in-person follow-up office visits. These office visits will occur 1 month after the patient starts the medication, 3 months afterwards, and 6 months afterwards. The final 6-month office visit will mark the conclusion of the patient's active participation in the study.

Inclusion Criteria: * Between 18 and 85 years old * Meeting CRPS diagnostic criteria using the Budapest Clinical Diagnostic Criteria * CRPS patients with severe pain (NRS\>3) that affects their daily life. * CRPS patients with pain and other symptoms for more than 3 months. Exclusion Criteria: * Patients with suspected disc herniation, spinal stenosis, myelopathy, and suspected radiculopathy in detailed examinations and examinations (MRI, CT). * Systemic or local infection * Malignancy * Current or planned pregnancy within the study period. * Uncontrolled medical and psychiatric condition * Patients with known liver issues, including but not limited to end-stage liver disease, severe cirrhosis or an acute hepatic state. * Patients who are currently using opioid drugs * Patients who are currently using alcohol or considering using alcohol during the study period. * Allergy to naltrexone or naloxone