Why would a doctor consider doing a lumbar sympathetic block on a patient?

Variety of reasons: A lumbar sympathetic block is performed to block the sympathetic nerves that go to the leg on the same side as the injection. This may in turn reduce pain, swelling, color, sweating and other unusual changes in the lower extremity and may improve mobility. It is done as a part of the treatment of Reflex Sympathetic Dystrophy (RSD), Sympathetic Maintained Pain, Complex Regional Pain Syndrome and Herpes Zoster (shingles) involving the legs. Certain patients with neuropathy or peripheral vascular disease may also benefit from lumbar sympathetic blocks.