What Is a Medial Branch Blocks?

A medial branch block (MBB) is a minimally invasive diagnostic procedure used to determine whether facet joints are the source of neck, mid-back, or low back pain.

Facet joints are small stabilizing joints located at each level of the spine. When these joints become irritated or arthritic, they can cause localized spinal pain that may worsen with twisting, bending backward, or prolonged standing. The medial branch nerves are small nerves that carry pain signals from these facet joints to the brain.

A medial branch block temporarily numbs these nerves to determine if they are responsible for your pain.

Why Is It Done?

Unlike epidural injections, medial branch blocks are primarily diagnostic rather than long-term treatment.

They are performed to answer a key question:

Are the facet joints the true source of your pain?

If your pain improves significantly after the block (typically 80% or more relief), this strongly suggests that facet joints are driving your symptoms. If so, you may be a candidate for a longer-lasting procedure called radiofrequency ablation (RFA).

How the Procedure Works:

The procedure is performed in an outpatient setting using live X-ray guidance (fluoroscopy).

During the block:

1. You lie comfortably on the procedure table.

2. The skin is cleaned and numbed.

3. A small needle is guided to the medial branch nerve at the targeted spinal level.

4. A small amount of local anesthetic is injected.

The procedure typically takes 10–20 minutes. Because only numbing medication is used (not steroid), the relief is temporary often lasting several hours.

You’ll be asked to carefully track your pain levels afterward to help determine how effective the block was.

Areas Treated:

Medial branch blocks can be performed in:

Cervical Spine (Neck)

For neck pain that may radiate to the shoulders or upper back.

Thoracic Spine (Mid-Back)

For midline or paraspinal thoracic pain, often worsened by extension or rotation.

Lumbar Spine (Low Back)

For mechanical low back pain, especially pain that increases with standing, arching backward, or twisting.

What to Expect After the Injection:

Because this is a diagnostic procedure:

• Relief should occur quickly (within minutes).

• Relief is temporary.

• You may be asked to perform activities that normally provoke your pain to assess response.

Significant temporary relief suggests the facet joints are the primary pain generator. If relief is minimal, another pain source may be considered.

Risks and Side Effects:

Medial branch blocks are generally very safe when performed under imaging guidance.

Possible side effects include:

• Temporary soreness at the injection site

• Brief numbness

• Mild increase in pain after the anesthetic wears off

• Rare bleeding or infection

Serious complications are uncommon.

What Happens Next?

If you experience substantial relief from one or two diagnostic medial branch blocks, radiofrequency ablation (RFA) may be recommended. RFA provides longer-lasting relief by disrupting the medial branch nerve’s ability to transmit pain signals, often for 6–12 months or longer.

If the block does not significantly improve your pain, your provider will reassess and explore alternative diagnoses and treatments.

Our Approach:

We use medial branch blocks thoughtfully and strategically, not as a reflex treatment, but as a precise diagnostic tool.

Spine pain can have multiple causes. Identifying the correct pain generator is critical before committing to longer-term procedures. Medial branch blocks allow us to make that determination with clarity and confidence, helping guide the safest and most effective next step in your care.

Reference:

Available at Spine-Health: “Medial Branch Nerve Blocks”