Lumbar Sympathetic Block

The sympathetic nerves are found on the front side of the spinal column. They are part of the autonomic pain relief4nervous system, which controls many body functions, such as heart rate, sweating, digestion, and blood pressure.

Sometimes, the sympathetic nerves continue to transmit pain signals following an injury, even when the injury heals. This transmission results in a condition known as complex regional pain syndrome (CRPS), which is also called reflex sympathetic dystrophy (RSD). A lumbar sympathetic block is a test the doctor uses to locate the cause of symptoms, which include burning pain, skin color changes, and swelling.

Why is the lumbar sympathetic block done?

If a patient has symptoms of CRPS, the doctor can identify the cause of the symptoms with the lumbar sympathetic block. During the procedure, the doctor injects a numbing medication (anesthetic) near the spine to block the sympathetic nerves of that region.

If these nerves are the cause of the symptoms, the injection offers temporary relief for a short time immediately after the procedure. The doctor can do a series of these blocks one to two weeks apart, which provides more long-lasting pain relief.

How do I prepare for the procedure?

The night before the procedure, you are to ingest no food or fluids after midnight. Small sips of water with necessary medications are allowed, however. Diabetics are advised to adjust or hold medications for diabetes. Certain medications must be discontinued days before the lumbar sympathetic block, such as blood thinners (Coumadin and Plavix). Be sure to discuss your medicationsSympathetic Block with the doctor well before the procedure. In addition, you need to have someone to transport you home, as driving after the block is not permitted.

What can I expect during the lumbar sympathetic block?

Right before the procedure, you are given instructions, informed of the risks and benefits of the block, and asked to sign a consent form. A nurse will place an intravenous (IV) catheter into your arm for fluids and/or sedative medications.

The staff will position you on your stomach on the procedure table, where the low back region is cleansed with an antiseptic. The doctor will numb the skin using a tiny needle and a local anesthetic. X-ray guidance is used to assure correct needle placement before the block is done. The doctor then injects a local anesthetic near the sympathetic nerves.

What can I expect after the procedure?

Once the medication is injected, you will be moved to the recovery area for 30 to 45 minutes. A nurse will monitor your vital signs and give you something to eat. Before discharge, you will be given discharge instructions.

Lumbar Sympathetic BlockYou will not be allowed to drive, bath, shower, or soak in water for the remainder of the day. The injection site will be sore and a little swollen for a few days, so use an ice pack for 20-minute intervals to alleviate the pain. You are allowed to resume normal activities the day following the lumbar sympathetic block.

What risks are associated with the lumbar sympathetic block?

While complications are rare, they include infection, pain at the injection site, allergic reaction to medications, and bleeding. The procedure cannot be performed if you have an active infection, such as the flu or a cold, or if you have a high blood pressure reading.

Is the lumbar sympathetic block effective?

Nerve blocks work by temporarily interrupting the conduction of impulses in peripheral nerves or nerve trunks created by instillation of a local anesthetic. These blocks can provide therapeutic relief of pain when administered correctly.

The response to a lumbar sympathetic block is the best diagnostic tool for CRPS/RSD. In recent research studies, over two-thirds of patients reported significant relief of pain with minimal effect on motor and sensory function.


Datta S, Everett CR, Trescot AM, et al. An updated systematic review of the diagnostic utility of selective nerve root blocks. Pain Physician. 2007; 10(1): 113-128.

Riew KD, Park JB, Cho YS, et al. Nerve root blocks in the treatment of lumbar radicular pain. A minimum five-year follow-up. J Bone Joint Surg Am. 2006;88(8):1722-1725.