Are done to treat nerve (neurogenic) pain, most commonly the constant burning pain of Reflex Sympathetic Dystrophy (RSD) (Complex Regional Pain Syndrome) (CRPS) in the arm or leg. Arm pain is treated by injecting the Stellate Ganglion in the neck, leg pain by the lumbar sympathetic chain in the low back. If the nerve block is done soon after the diagnosis is made, combined with vigorous physical therapy, the RSD is often curable. If treatment is delayed, the CRPS may not be curable, and lead to permanent disability. Long-term pain relief is also available with Electrical stimulation of the posterior spinal cord.