This is a double-blind randomized controlled trial to evaluate the efficacy of the sympathetic block via thoracic vertebra T3 for the treatment of CRPS I upper limb. Patients with CRPS I refractory to medical treatment will be subjected to four physical therapy sessions and then the randomized for experimental or control block and then more four physiotherapy sessions. Patients will be evaluated after one month of the blockade (primary outcome) and then up to 12 months. Will be evaluated by analgesic scale (Mcgill, brief pain inventory, dn4 questionnaire, NPSI, VAS), functional (ADM) and quality of life (HAD and WHOQOL-brief).

Inclusion Criteria:

• Complex regional pain syndrome (IASP, 1994) involving an upper limb;
• Pain scores in excess of five visual analog scale (VAS);
• Poor outcome to treatment (less than 50% reduction in VAS scores) -

Exclusion Criteria:

• History of severe brain injury, epilepsy and stroke
• Patients who had undergone sympathetic ganglion block for treatment of the affected limb, by any technique
• Severe systemic disease
• Addictive behavior, severe psychiatric disorders, psychiatric diseases untreated
• Refusal to participate or not initial adherence to orientations
• Refusal to be randomized in a treatment group or with contraindications to any of them pregnancy.