A lumbar sympathetic block is an injection placed in or near the sympathetic nerves. Located in the lumbar (lower) spine on each side of the backbone, these are the nerves responsible for regulating blood flow to legs and other basic functions. These nerves also play a role in transmitting pain signals from tissues in the immune system and skin (peripheral tissues) to the spinal cord. If the sympathetic nerves are contributing to lower back pain, a nerve block may provide relief.
Why Consider a Lumbar Sympathetic Block?
A lumbar sympathetic block may be recommended to treat lower back or sciatic nerve pain not responding well to conservative (non-surgical) treatments. An injection is sometimes used to block nerve sensations relegated to one leg, a common symptom of sciatica. The medication in the injection may minimize swelling and ease pain from nerve irritation enough to improve mobility. A lumbar sympathetic block may also recommended to manage pain related to:
• Reflex sympathetic dystrophy (RSD)
• Herpes Zoster (shingles) affecting legs
• Neuropathic or peripheral vascular diseases
What's In the Injection?
The nerve block injection includes a local anesthetic to minimize discomfort from the shot. The anesthetic sometimes provides added relief as nerves and tissues are numbed. A steroid medication is often included to extent the effects of the nerve block.
How is a Lumbar Sympathetic Block Performed?
Some patients respond better to the procedure with mild sedation from an intravenous medication. The patient is placed in a comfortable position during the procedure to allow access to the part of the lower back where the injection will be administered. The area is numbed with a local anesthetic and the doctor places the needle in the lower back area with the guidance of a special live X-ray. A dye may be used to ensure that the medication is delivered to the correct location. The procedure usually takes about half an hour to complete.
What Happens After the Injection?
Some patients report immediate relief after the injection while others experience noticeable results with a few weeks once the steroids have had a chance to work. Some warmth may be felt in the affected area or legs as pain subsides and the medication takes effect. Strenuous activity should be avoided for about 24 hours before returning to a normal routine.
How Safe is It?
Nerve blocks are generally considered safe for most patients. It's not recommended for anyone with an active infection or conditions like diabetes that aren't properly managed. Some temporary soreness may be experienced at the injection site, but this is normal and usually goes away shortly after the shot is given.
Results from a lumbar sympathetic block will depend on whether or not there are additional factors contributing to lower back or radiating nerve pain, such as a herniated disc or pressure on the sciatic nerve or sacroiliac (SI) joint. Injections may also be used to identify other possible pain sources. Some patients will benefit from a handful of injections while others report better results with more shots. Effects from the block usually last longer after each injection.