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)

The purpose of this study is to assess the efficacy of pregabalin in patients with complex regional pain syndrome Type I and to determine whether it provides clinically significant pain relief and whether it improves functioning of the upper limb.

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