Thoracic sympathetic block for the treatment of complex regional pain syndrome type I: a double-blind randomized controlled study.

Pain relief in complex regional pain syndrome (CRPS) remains a major challenge, in part due to the lack of evidence-based treatment trials specific for this condition. We performed a long-term randomized, double-blinded active-control study to evaluate the efficacy of thoracic sympathetic block (TSB) for upper limb type I CRPS. The study objective was to evaluate the analgesic effect of TSB in CRPS. Patients with CRPS type I were treated with standardized pharmacological and physical therapy and were randomized to either TSB or control procedure as an add-on treatment. Clinical data, pain intensity, and interference (Brief Pain Inventory), pain dimensions (McGill Pain Questionnaire [MPQ]), neuropathic characteristics (Neuropathic Pain Symptom Inventory [NPSI]), mood, upper limb function (Disabilities of Arm, Shoulder and Hand), and quality of life were assessed before, and at 1 month and 12 months after the procedure. Thirty-six patients (19 female, 44.7 ± 11.1 years of age) underwent the procedure (17 in the TSB group). Average pain intensity at 1 month was not significantly different after TSB (3.5 ± 3.2) compared to control procedure (4.8 ± 2.7; P=0.249). At 12 months, however, the average pain item was significantly lower in the TSB group (3.47 ± 3.5) compared to the control group (5.86 ± 2.9; P=0.046). Scores from the MPQ, evoked-pain symptoms subscores (NPSI), and depression scores (Hospital Anxiety and Depression Scale) were significantly lower in the TSB group compared to the control group at 1 and at 12 months. Other measurements were not influenced by the treatment. Quality of life was only slightly improved by TSB. No major adverse events occurred. Larger, multicentric trials should be performed to confirm these original findings.