A lumbar sympathetic plexus block is administered to block the sympathetic nerves that provide information and function to the lower extremities. This treatment may in turn, reduce pain, swelling, color and sweating changes in the lower extremity, and may also improve mobility.

It is done as a part of the treatment of complex regional pain syndrome (CRPS, and sometimes called reflex sympathetic dystrophy or RSD) and herpes zoster (shingles) involving the legs.

During the procedure:

• You will be asked to lie on your stomach.
• Your lower back will be cleaned with an antiseptic, and a sterile drape will be placed.
• Your physician will inject a numbing medication (local anesthetic) to numb the skin.
• A needle will then be guided to the targeted vertebral body — typically L2 and L3.
• Contrast dye will be injected to confirm the location of the needle along the targeted landmark and to ensure the needle is in safe position.
• A small volume of numbing medicine will be injected onto the lumbar sympathetic plexus.
• The needles will be removed, and a sterile dressing will be applied.

There are some expected changes that result from blocking the sympathetic nerves. These changes are temporary and may last about 4-6 hours. Such changes include the following symptoms on the same side as the injection: a temperature increase in the leg. You may also experience some fullness of the leg due to increased blood flow from the nerve block. This is a normal and expected outcome.