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Medical Branch Nerve Block

The vertebral bones are separated by discs (aka “cushions”) on the front part of the spine. Along the back part of the spine, the vertebral bones contact each other on both sides and form facet joints. There are right and left facet joints at each level of the spine. Facet joints stabilize the spine during movement. However, over time, repetitive strain on these joints can cause inflammation.

Pain signals from each facet joint are transmitted by the medial branch nerve to the brain.

This nerve only carries signals of pain. It does not control your ability to move. Therefore, a small amount of numbing medication (local anesthetic) can be injected along the nerve to decrease or “numb” the pain originating from these joints. If you experience substantial pain relief for the duration of the local anesthetic (usually 6-8 hours), we have confirmed the facet joint as the source of your pain.

Although history, physical exam, and imaging studies may suggest that your pain is due to your facet joints, the only way to definitively confirm this is to receive a medial branch nerve block or facet injection. Medial branch nerve blocks can help diagnose pain from facet arthritis, degeneration of the facet joint, facet hypertrophy, and facet edema. In addition, this procedure opens up avenues of treatment for longer lasting relief such as radiofrequency denervation.

How It Works

Medial branch nerve blocks are performed under live fluoroscopic guidance to ensure the accuracy and safety of this procedure.

  • You will be asked to lie on your stomach or side.
  • The injection area will be cleaned with an antiseptic, and a sterile drape will be placed.
  • Your doctor will guide a needle toward an easily visible bony target to approximate the location of each medial branch nerve.
  • Next, your physician will deposit a small amount of numbing medicine at the target sites.
  • Finally, a needle will be removed, and a sterile dressing will be applied.

You will be discharged with a pain diary that tracks your pain level for the next 24 hours. If you receive substantial pain relief (80%) for the duration of the numbing medicine (usually 6-24 hours), we have confirmed the facet joint associated with that medial branch nerve as the source of your pain. For longer lasting relief, you may receive radiofrequency denervation of the medial branch nerves.


Similar to any other procedure or medication, there are potential risks — although very low. These include infection, bleeding, allergic reaction, and prolonged increases in pain. Your Center for Pain Management physician will use sterile techniques and x-ray guidance throughout the procedure to significantly reduce the risks.