What Are Lumbar Sympathetic Blocks?

Lumbar sympathetic blocks involve injections of a local anesthetic in an effort to achieve analgesia (pain relief) in the lower back, buttocks, or legs. The local anesthetic is injected into or around the area of the lumbar sympathetic nerves. The local anesthetic can be combined with a steroid, a potent inhibitor of inflammation, which can provide prolonged pain relief. Infrequently, the local anesthetic is combined with clonidine or adrenaline in an effort to achieve extended pain relief.

There are two divisions of the nervous system—central and peripheral. The peripheral nervous system governs automatic functions such as heart rate, digestion, blood pressure, breathing, and sweating. The peripheral nervous system has two divisions—sympathetic and parasympathetic. Both divisions of the peripheral nervous system work in tandem. The sympathetic nervous system arises from the thoracic and lumbar areas of the spinal cord. The nerves of the sympathetic system are deep and run bilaterally in a parallel fashion along the spine.

The lumbar sympathetic nerves can sometimes continue to emit pain signals, even after healing of a nerve injury or irritation. Oral narcotic medications, although sometimes helpful, cannot adequately control the pain attributed to the sympathetic nerves. Lumbar sympathetic blocks can be used to diagnose and treat pain and cardiovascular disease affecting the legs.

How Are Lumbar Sympathetic Blocks Performed?

Following a discussion with the physician about the pros and cons of lumbar sympathetic blocks, the patient will sign an informed consent form. On the day of the procedure, the patient will be placed in a prone or lateral position on a table. The lateral position is usually reserved for patients who cannot tolerate the prone position. Sedatives can be given orally or through an IV to keep the patient calm throughout the procedure. The physician then sanitizes the injection area with an antiseptic solution.

Landmarks are used to mark the area of injection. A local anesthetic is injected to numb the skin. Using X-ray guidance, another needle filled with local anesthetic is positioned near the sympathetic nerves. Sometimes contrast (dye) is used to confirm correct needle placement. After confirmation, the local anesthetic, with or without a steroid, is slowly injected and the needle is withdrawn. The local anesthetic can be lidocaine, which is short acting, or bupivacaine, which is long acting. The procedure can be performed on one or both sides.

Lumbar sympathetic blocks can be performed in 30 minutes or less. The patient is monitored for a period of time, usually 30 to 45 minutes, and sent home in stable condition. Briefly after the injections, patients may report a reduction or complete resolution of symptoms. The temperature will also increase in the affected leg. If effective, lumbar sympathetic blocks may be repeated every one to two weeks for prolonged relief of pain. The number of injections varies from patient to patient. Some may need a series of two, and others upward of ten, for sustained pain relief.

There are usually minimal complications with lumbar sympathetic blocks. Tenderness and bruising at the injection site are the most prevalent complications. Other uncommon complications include allergic reaction to the medication injected, infection, nerve damage, bleeding, low blood pressure (hypotension), bloody urine (hematuria), anesthetic toxicity, headaches, spinal or epidural block, blood collection (hematoma), direct intravascular injection, failure to ejaculate, and numbness or weakness in the lower extremities.

If a steroid is added to the local anesthetic, complications could include weight gain, thinning and weakening of bones (osteoporosis), and weakening of the immune system (immunosuppression).

Lumbar sympathetic blocks should not be performed in patients with the following:

  • Active infection, viral or bacterial, requiring or not requiring antibiotics
  • Taking blood thinners (e.g. Coumadin, aspirin, Pletal, Plavix)
  • Uncontrolled heart disease or diabetes mellitus
  • Allergies to injectables such as local anesthetics, steroids, adrenaline, or clonidine
  • Fever of 100.5 or greater
  • Blood disorders
  • Cancer in the area of injection
  • Vascular malformations in the area of injection

Blood thinners such as Coumadin, aspirin, Pletal, or Plavix should be discontinued five to seven days prior to lumbar sympathetic blocks. Blood thinners may be resumed shortly after the procedure. The procedure can also be rescheduled once better control of heart disease or diabetes mellitus is established.

Conditions Related To Lumbar Sympathetic Blocks

Indications for the administration of lumbar sympathetic blocks include:


Lumbar sympathetic blocks are useful in the diagnosis and treatment of painful and circulatory conditions affecting the lower back and legs. The procedure employs the infiltration of an anesthetic close to the lumbar sympathetic nerve chain. X-ray guidance, or fluoroscopy, may increase success rates and decrease the chance of complications. Most patients report some improvement in symptoms after lumbar sympathetic blocks. Overall, lumbar sympathetic blocks are minimally invasive with a paucity of serious side effects or complications.


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