What is a sympathetic nerve block?

A sympathetic nerve block helps your healthcare provider find the cause of the burning, pain, or tingling in your arms and hands or legs and feet. During the test, medicine is injected near your spine. This “blocks” the sympathetic nerves in that area.

The sympathetic nervous system is a network of nerves all over your body. The nerves branch from your spine. This nervous system controls several involuntary body functions, or body functions that you have no control over. These include blood flow (opening and closing of blood vessels), digestion, and opening the sweat glands. A problem with these nerves can affect blood flow. Symptoms are often felt in the hands or feet. They may hurt, burn, feel cold, or be sore to the touch.

The sympathetic nervous system is controlled by bunches of nerves called ganglions. One large ganglion, called the stellate ganglion, helps control nerves in the upper body. In the lower body, nerves are controlled by several ganglions that make up the sympathetic chain. The location of your pain often determines where you'll receive the nerve block. If you have pain in the upper part of your body, you may get pain relief from blocking the stellate ganglion in your neck area. If you have pain in the lower part of your body, a ganglion near the lower spine may be targeted with a lumbar sympathetic block

If these nerves are causing your problem, the injection will ease your symptoms for hours, days, or longer. This injection is used both to help diagnose and to treat certain nerve problems, including long-lasting (chronic) pain.

A sympathetic nerve block is believed by many pain healthcare providers to be an effective method for controlling chronic pain. But there is not a lot of medical evidence to show if these blocks are actually helpful.

Why might I need a sympathetic nerve block?

A sympathetic nerve block can be used to diagnose or treat pain involving the nerves of the sympathetic nervous system. Examples of conditions for which a sympathetic nerve block might be used include:

• Pain from spasms in the blood vessels

• Complex regional pain syndrome, previously called reflex sympathetic dystrophy and causalgia

• Raynaud syndrome

• Some types of chronic stomach pain

• Excessive sweating

• Burning, pain, or tingling in your arms, hands, legs, or feet

What are the risks of a sympathetic nerve block?

Risks and complications are rare but can include:

• Bleeding or fluid leakage in the spinal cord

• Puncture of a blood vessel

• Infection

• Lung puncture

• Nerve injury

How do I get ready for a sympathetic nerve block?

You will meet with a pain management specialist experienced in doing nerve blocks.

You will review your health history with your healthcare provider. Tell your provider if you have an infection, fever, or other recent health problems. If you have diabetes or use any blood-thinning medicines, ask if you will need to take any special precautions.

Tell your healthcare provider about all the medicines you take. This includes over-the-counter medicines, herbs, vitamins, and other supplements. You may need to stop taking certain medicines a few days before the shot.

Also tell your healthcare provider if you:

• Have any allergies

• Have had any problems with contrast dyes, past injection procedures, anesthesia, or other medicines. You may get medicine to help you relax during the injection.

• Are pregnant or think you may be pregnant

Also be sure to:

• Follow any directions you are given for not eating or drinking before the procedure.

• Ask a family member or friend to drive you home after the procedure.

• Follow any other instructions from your healthcare provider.

What happens during a sympathetic nerve block?

This is what happens during a typical sympathetic block procedure:

• The medical team starts an IV (intravenous) line and watches your vital signs carefully.

• You may be given some medicine through the IV line to make you relaxed and sleepy.

• Before the actual block, the area in your neck or back will be made numb with a local anesthetic.

• X-rays (or fluoroscopy) may be used to help the specialist find the right ganglion.

• Once the ganglion is located, an anesthetic solution will be injected into the location. In some cases, other chemicals are used.

• After the injection, the needle will be removed and pressure will be applied. The site will be covered with a small bandage.

• If the sympathetic nerves are causing your problem, the temperature in your hands or feet will rise quickly. You may also see some flushing of the skin in the area. The block will relieve your symptoms for a while. Sympathetic nerve blocks may give long-term relief from symptoms. For this treatment, a few blocks are given 1 to 2 weeks apart.

What happens after a sympathetic nerve block?

You will stay in a recovery area for about an hour. A sympathetic nerve block is a relatively safe procedure. You can often go home afterward and return to your normal activities after a day of rest. Your healthcare provider can tell you when it’s OK to return to work. If you had IV sedation, you'll likely need to have someone drive you home.

Side effects after a sympathetic block may include short-term (temporary) soreness, a feeling of warmth, or some weakness. If you've received a nerve block in the stellate ganglion, you may have some temporary voice changes, eyelid droop, or trouble swallowing. Until swallowing is back to normal, take small bites of food and sip drinks carefully.

Physical therapy, talk therapy, and pain medicine may all be part of your treatment along with a sympathetic nerve block. In most cases, you will be given a series of blocks to get the best possible response.

Sympathetic blocks don't work for everyone. Also, the pain relief they give may lessen over time. But for some people, a sympathetic block may give weeks or months of pain relief.

Next steps

Before you agree to the test or the procedure, make sure you know:

• The name of the test or procedure

• The reason you are having the test or procedure

• What results to expect and what they mean

• The risks and benefits of the test or procedure

• What the possible side effects or complications are

• When and where you are to have the test or procedure

• Who will do the test or procedure and what that person’s qualifications are

• What would happen if you did not have the test or procedure

• Any alternative tests or procedures to think about

• When and how you will get the results

• Who to call after the test or procedure if you have questions or problems

• How much you will have to pay for the test or procedure