Most of our body functions and involuntary processes are handled by the autonomic system, which is loosely grouped into the sympathetic and parasympathetic nervous systems. These nerves control functions such as heart rate, blood pressure, digestion, sweating, and blood flow (i.e., prioritizing where to shunt blood). Trunks of the sympathetic nerves are grouped and found along the front side of our spinal column.
A lumbar sympathetic block is done for diagnostic and therapeutic reasons. Your doctor will be able to identify the sources of pain, based on the success of the nerve block; and the block will relieve conditions that cause excessive stimulation of the sympathetic nerve. This is a procedure that is usually considered after more conservative treatments, such as with oral medications, have failed.
When is a lumbar sympathetic block indicated?
There are conditions that cause the sympathetic nervous system to be excessively stimulated, such as the Complex Regional Pain Syndrome (also known as Reflex Sympathetic Dystrophy). Diseases such as herpes zoster (or shingles), neuropathies, and peripheral vascular disease have also been shown to respond to this therapy. Chronic pain has also been shown to respond to sympathetic blocks.
How is the procedure carried out?
Sympathetic nerve blocks are done under local anesthesia, but you may be given a mild sedative in order to calm you down. The procedure requires a sterile technique, so the surgical site will be prepped with an antiseptic solution, and the surrounding area draped with sterile linen.
The needle is inserted under fluoroscopic (X-ray) guidance, going through muscle and tissue until the target area is reached. Local anesthetic is then introduced into the area. Other guiding modalities have been of use in recent years, such as computerized tomography (CT), magnetic resonance imaging (MRI) and ultrasonography.
If the block is successful, you will see signs of relief from the sympathetic overstimulation, such as lessening of reddening, an increase in temperature, and relief of pain. Once success is confirmed, the surgeon will withdraw the needle, or complete other nerve blocks as necessary.
The procedure can take less than half an hour, depending on the exact circumstances of the case and the experience of the physician. You will be kept under observation in recovery after the procedure, and if no untoward signs are seen, can even be sent home within the day.
What are the outcomes and risks of a sympathetic nerve block?
Lumbar sympathetic nerve blocks have generally positive outcomes, with most patients experiencing relief of symptoms. Adverse effects are rare, and are most often related to bruising and pain at the insertion site. These complaints are easily managed with medications. There is also a risk for infection at the surgical site, and intraoperative damage to the surrounding nerves, muscles and tissues. Rare complications such as priapism and disc herniation have also been reported.
Patients who suffer from bleeding or clotting disorders, or who have infection over the surgical site, should not be allowed to undergo the procedure. Your physician will advise you on the requirements for medical clearance.
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