A lumbar sympathetic block is an injection performed to treat and diagnose sympathetic pain.
The sympathetic nerves are located on either side of the spine, in the lower back. Normally these nerves control basic functions like regulating blood flow, although in certain conditions, the sympathetic nerves can carry pain information from the peripheral tissues back to the spinal cord. A lumbar sympathetic block typically involves a series of injections to relieve leg pain, or sciatica, caused by complex regional pain syndromes, usually after injury to a joint or limb.
The procedure will most likely have to be repeated to produce a long-lasting benefit. The spacing of injections will be based on how long the pain relief lasts between injections. Typically, you will experience a longer benefit following each subsequent injection.
A lumbar sympathetic block is performed under x-rays, using a thin needle. Local anesthetics will numb the group of nerves, decreasing pain. Changes in sweat and temperature may be observed. The procedure is performed as an outpatient, but sedation is offered.
Lumbar sympathetic blocks may have therapeutic or diagnostic value. One of two things will happen:
- The pain does not go away, and there is evidence of a sympathetic block. The fact that the pain is unresponsive to sympathetic blocks is of diagnostic value.
- The pain goes away after the injection and stays away longer than the life of the local anesthetic. This means the block was of therapeutic value.