Neuroimaging Study on the Effect of Transdermal Buprenorphine in Complex Regional Pain Syndrome Patients

Inclusion Criteria: 1. Patients diagnosed with complex regional pain syndrome Type I (Budapest Criteria) and persistent back pain (VAS ≥ 4). 2. Patients who can stop benzodiazepine treatment 2 weeks before study 3. Patients who initially decided to use buprenorphine according to clinical judgment 4. Patients who are able to understand the purpose and procedure of the study Exclusion Criteria: 1. Patients with an impaired cognitive function such as psychosis, dementia, or mental retardation 2. Patients with neurologic disease, cerebrovascular disease, history of brain tumor, history of severe head trauma, history of convulsive disease 3. Patients with cardiovascular disease, liver, respiratory or renal dysfunction 4. Patients with biliary disease 5. Patients who could not undergo the PET/magnetic resonance imaging (MRI) process. 6. Patients who have a risk of suicide or show aggressive behavior 7. Patients who have drug dependence (DSM-IV criteria) or history (past 6 months or older) 8. Employees of researchers or clinical research institutes 9. Patients with hypersensitivity or contraindication to buprenorphine