Medial Branch Block (MBB)

A Medial Branch Block (MBB) is a diagnostic and sometimes therapeutic injection used to determine whether the facet joints in the spine are the source of your back or neck pain. It involves injecting a local anesthetic near the medial branch nerves that supply the facet joints.

If your pain improves significantly after the injection, it confirms that these joints are likely the source of your symptoms.

• To identify the cause of back, neck, or mid-back pain
• To determine if you are a candidate for radiofrequency ablation (RFA)
• Occasionally used to provide temporary relief of facet joint pain

• Cervical spine (neck)
• Thoracic spine (mid-back)
• Lumbar spine (lower back)

• Discuss all medications with your provider, especially blood thinners.
• You may be asked to fast for 6–8 hours if sedation is planned.
• Arrange for transportation home if sedation is used.
• Continue most medications unless otherwise instructed.

• You will lie on your stomach (or face-up for cervical injections).
• The skin is cleaned and numbed with local anesthetic.
• Using fluoroscopy (live X-ray) for guidance, the provider will insert small needles near the targeted medial branch nerves.
• A small amount of local anesthetic (no steroid) is injected.
• Procedure time: 15–30 minutes
• Sedation: May be used, but often unnecessary

What to Expect:

• Relief may be felt within 15–30 minutes if the medial branch nerves are contributing to your pain.
• Soreness at the injection site may occur for 1–2 days.
• Keep a pain diary to track how much relief you experienced and how long it lasted.

Activity:

• Rest the day of the procedure.
• Resume light activity the next day unless told otherwise.
• Avoid strenuous exercise for 24 hours.

• A positive result (at least 80% pain relief) may lead to radiofrequency ablation (RFA), which provides longer-lasting relief.
• If there is no relief, the facet joints may not be the primary pain source, and other options will be explored.

Although rare, risks may include:

• Temporary increase in pain
• Bruising or bleeding
• Infection
• Nerve irritation
• Allergic reaction to medications
• Dizziness or lightheadedness

• MBB is mainly diagnostic, not a long-term pain solution on its own.
• It helps determine if RFA is appropriate for longer-term relief.
• Tracking your pain relief after the procedure is critical to the decision-making process.

If the MBB provides significant temporary relief, your doctor may discuss doing a radiofrequency ablation (RFA), which can provide longer-lasting pain relief by disrupting the nerve's ability to send pain signals. Insurance requires this to be at least 80% effective for the 1st to the 6th hour in order to proceed with ablation.