What is a Medial Branch Block?


This diagnostic procedure is performed to identify a painful facet joint. The facet joints are the joints between the vertebrae in the spine. They allow the spine to bend, flex and twist.


In preparation for the procedure, the patient is positioned on his stomach. The provider injects a local anesthetic. This numbs the skin and tissue around the facet joint that is suspected of causing the patient’s pain.

Contrast Dye Injected

Once this tissue is numb, the provider inserts a needle into the skin. The needle is carefully guided down to the facet joint. The provider injects a contrast solution through this needle. The contrast solution helps the provider see the area on a camera called a fluoroscope. The fluoroscope provides live x-ray images. The provider uses the fluoroscope to confirm the location of the needle’s tip.

Anesthetic Injected

Once the provider has confirmed that the needle is positioned correctly, the provider attaches a syringe containing an anesthetic medication. This medication is injected around small nerves called the medial branch nerves. These carry signals to and from the facet joints. The anesthetic will temporarily block sensation in these nerves.

End of Procedure

If the temporary injection relieves the patient’s pain, the provider may inject a more long-lasting anesthetic. If the temporary injection does not relieve the pain, the provider may test nearby facet joints to identify the correct one.