Thoracic sympathetic ganglion block is a percutaneous procedure that paralyzes the action of sympathetic nerves transiently by injecting a local anesthetic around the ganglion. It is performed to diagnose and treat sympathetically maintained pain in phantom limb pain or complex reginal pain syndrome patient. The temperature of the affected arm is often lower than that of the opposite side. As a result of the procedure, the patient may experience sympathetic pain relief, such as coldness, stinging, numbness of the upper extremity. If the procedure does not last long, repetitive block or chemical neurolysis or radiofrequency thermocoagulation for the sympathetic ganglion is performed.

However, even though in rare cases, chemical neurolysis is known to cause permanent plexus injury radiofrequency thermocoagulation is known to be less successful than chemical neurolysis because it is difficult to identify and stimulate the exact location of the ganglion. Therefore, it is expected that there will be a benefit to the patients if there is a procedure with long-lasting and avoiding injury.

Recently, it has been reported that botulinum toxin (BTX) has been successfully used for the treatment of pain disorders. BTX plays a role with blocking the secretion of acetylcholine from the cholinergic nerve endings. Therefore, the use of BTX is expected to prolong the effect of neural blockade because pre-ganglia sympathetic nerves are cholinergic. It is also known that the action of BTX is not permanent and BTX does not exhibit cytotoxicity or neurotoxicity. Therefore, Botulinum toxin type A (BTA) is recommended for the treatment of migraine, myofascial pain syndrome, and neuropathic pain accompanied by allodynia. This study would like show whether thoracic sympathetic ganglion block using BTA has a longer duration than conventional local anesthesia by using prospective randomized, double-blind, parallel group, and comparative clinical trials.

Inclusion Criteria:

1. aged 19-80 years
2. Diagnosed with a complex regional pain syndrome (type 1 or 2) in unilateral upper extremity
3. 11-point numerical-rating-scale (NRS) pain score of 4 or higher in upper extremity
4. Temperature increase at diagnostic thoracic sympathetic ganglion block
5. Patients taking medication stably (without change in dosage/recipe) for more than 4 weeks prior to administration

Exclusion Criteria:

1. Refusal of the patient
2. Vascular disease at upper extremity
3. previous thoracic sympathetic neurolysis (thermocoagulation, chemical neurolysis)
4. coagulopathy
5. systemic infection or local infection at thoracic puncture site
6. significant deformity at thoracic spine
7. neoplasm
8. known allergic reaction with amide type local anesthetics
9. cognitive dysfunction (not understanding of numerical-rating-scale)
10. known allergic reaction with botulinum toxin
11. pregnant or feeding women
12. If the patient has participated in another clinical trial within 30 days before screening, or if passed no longer than 5-fold half-life of the clinical trial drug of the participating clinical trial