Medial Branch Block

What is a Medial Branch Block?

A Medial branch block is a injection of local anesthetic and steroids placed outside the joint space near the nerve that supplies the joint called the medial branch.

Medial branch blocks are typically used for patients who have pain primarily in their back coming from arthritic changes in the facet joints or for mechanical low back pain. You may require multiple injections depending upon how many joints are involved.

After you are evaluated by a nurse, the procedure will be done in the fluoroscopy room with you lying on your stomach. For procedures in the neck, an intravenous is started.

The back or neck is then cleansed with an antiseptic soap. Sterile drapes are placed. The skin is anesthetized (numbed) with a local anesthetic. This is felt as a stinging or burning sensation. Using fluoroscopy guidance, needles are then advanced to the medial branches.

Once the needles are in the proper location, local anesthetic is injected through the needles, and the needles are removed. Your skin will be cleansed and bandages will be applied.

A Medial branch block procedure is a diagnostic procedure. One of three things may happen:

  • The pain does not go away, which means that the pain is probably not coming from the blocked facet joints. This has diagnostic value.
  • The pain goes away and stays away for a few hours, but the original pain comes back and doesn¹t get better again. This would mean the block was also of diagnostic value, indicating that the pain is probably coming from the joints but the steroid was not of benefit.

If you get a positive, short-term benefit, another procedure called radiofrequency lesioning may be done which may last months to years.The radiofrequency procedure can only be performed after two of the medial branch blocks are performed and have a positive result.

As with most procedures, there is a rare risk of bleeding, infection, nerve injury or allergic reaction to the medications used. Some short-term side effects may occur. If local anesthetic spreads to nearby nerves, you may have weakness or numbness that can last for several hours. If this happens you may have to stay in the procedure area until this resolves. You may have increased pain for a few days after the injection, including localized pain at the injection site.