Pregabalin Versus Placebo as an Add on for Complex Regional Pain Syndrome (CPRS) of the Upper Limb Managed by Stellate Ganglion Block (The PREGA Study)

Inclusion Criteria: * Patients diagnosed with CRPS Type I as per the IASP (International Association for the Study of Pain) criteria which states presence of an initiating noxious event, or cause for immobilization * Evidence at some point of swelling, color change, hot/cold/sweaty sensation and no other condition which can account for the pain and dysfunction of the upper limb * Men or women between ages 18-65 year old * Women should not be pregnant or breast feeding * No change in treatment for 4 weeks prior to recruitment * Pain scores of 4/10 on a verbal analogue scale Exclusion Criteria: * Patients with a neurologic disorder unrelated to CRPS * Patients who are already on pregabalin * Patients with renal impairment whose creatinine clearance is less than 60 ml/min * Patients with congestive heart failure who are also diabetic and taking thiazolidinedione medication like rivoglitazone * Unstable psychiatric history * Patients with another problem with equal or worse pain * Unstable medical condition