Lumbar Medial Branch Block

A lumbar medial branch block checks if facet joints are the source of your long-term low back pain. It also shows if you are a good fit for radiofrequency ablation. Guided by live X-ray at Remix Medical in Houston, TX.

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By Raju Mantena, DO · Pain Medicine PhysicianReviewed Jul 9, 20262 min read

Key takeaways

A lumbar medial branch block places a small volume of local anesthetic on the medial branch nerves that carry sensation from the facet joints — fundamentally a diagnostic test, not a lasting treatment.
Facet joint pain accounts for roughly one in five cases of chronic low back pain, and there's no imaging finding or exam maneuver that proves it — anesthetizing the nerves and seeing whether the pain stops is the only reliable way to identify it.
A positive block (typically 50–80% relief of familiar pain during the anesthetic window) confirms the facet joints as the source and identifies the patient as a candidate for radiofrequency ablation.
Most protocols require two separate positive blocks on different days before ablation, because a single block has a meaningful false-positive rate — double blocks substantially improve the odds that ablation will work.
A negative block is equally valuable: it rules out the facet joints and redirects the workup toward the disc, SI joint, or nerve root. Sedation is minimized to avoid confounding the result.

Lumbar Medial Branch Block in Houston, Texas

About one in five patients with chronic low back pain has facet joint pain. There is no imaging finding that proves it and no physical exam maneuver that confirms it. The only reliable way to identify it is to anesthetize the nerves that carry sensation from those joints and see whether the pain stops.

That is what a lumbar medial branch block does.

What is a Lumbar Medial Branch Block?

Each facet joint in the lumbar spine receives sensory innervation from two small nerves called medial branches. A medial branch block places a tiny volume of local anesthetic onto those nerves under fluoroscopic guidance.

If your familiar pain substantially disappears for the duration of the anesthetic, the facet joint at that level is confirmed as the pain generator. If it does not, the facet joint is not the source — which is equally valuable information.

Stage	What happens
Before	You're positioned, the skin is cleaned and numbed, and live imaging (fluoroscopy or ultrasound) guides the needle
During	The medication is placed precisely at the small nerves feeding your lower-back facet joints; most people feel pressure more than sharp pain
After	You rest briefly and go home the same day — arrange a driver if you received sedation

Diagnostic First, Therapeutic Second

This is fundamentally a diagnostic test. Its purpose is to determine whether you are a candidate for radiofrequency ablation, which provides durable relief by interrupting those same nerves.

Most protocols require two separate positive blocks on different days before proceeding to ablation. This double-block standard exists because a single block has a meaningful false-positive rate. Doing it properly means one extra visit; skipping it means a meaningful fraction of patients undergo an ablation that was never going to work.

Who It Helps

Axial low back pain without radiation below the knee
Pain worse with extension, standing, or twisting
Pain eased by sitting or forward flexion
Morning stiffness that loosens with movement
Tenderness over the paraspinal region
Degenerative facet arthropathy on imaging, correlated with symptoms

Confirming the Source at Remix Medical

There is no substitute for knowing precisely where pain originates.

How it's performed

The patient lies prone under live fluoroscopy. After skin anesthesia, a fine needle is advanced to the junction of the transverse process and superior articular process at each target level, where the medial branch nerve runs. Correct position is confirmed radiographically, and a small volume of local anesthetic is deposited on each nerve. The patient then records pain scores over the following hours to establish whether the block was positive.

How to prepare

Do not take pain medication immediately before the procedure — it can obscure the diagnostic result. Arrange a driver. Hold anticoagulants only as directed by the prescribing physician. Bring a pain diary or be prepared to record pain scores for several hours afterward.

What to expect after

Record your pain level hourly for 8 hours after the block using a 0 to 10 scale, and bring the diary to your follow-up. Resume normal activity immediately — in fact, deliberately test the movements that usually hurt. Expect the relief to wear off as the anesthetic does. Report fever, spreading redness, or new weakness.

Outcome

A positive block — substantial short-term relief of the familiar pain — confirms the facet joints as the pain source and identifies the patient as a candidate for radiofrequency ablation, which typically provides 6 to 12 months of relief.

Frequently asked

Lumbar Medial Branch Block questions, answered

What is a lumbar medial branch block?

It's a numbing injection to the small nerves that carry pain from the facet joints in your lower back. It's mainly used to test whether those joints are the source of your pain.

Why is a medial branch block done?

If numbing those nerves relieves your back pain, it confirms the facet joints as the source and predicts that radiofrequency ablation will help. It's a diagnostic step.

What happens if the medial branch block works?

Good relief usually means you're a candidate for radiofrequency ablation, which quiets those nerves for a longer period. Your doctor discusses that next step.

Does a medial branch block hurt?

The skin is numbed and imaging guides the needle, so you'll feel mostly pressure. Some soreness afterward is normal.

How long does a medial branch block last?

The numbing effect is usually short, since it's a diagnostic test. The longer relief comes from the ablation it helps plan.

Sources

References

Cohen SP, Bhaskar A, Bhatia A, et al. Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty international working group. Reg Anesth Pain Med 2020;45(6):424–467 — https://doi.org/10.1136/rapm-2019-101243
Conger A, Burnham T, Salazar F, et al. The Effectiveness of Radiofrequency Ablation of Medial Branch Nerves for Chronic Lumbar Facet Joint Syndrome in Patients Selected by Guideline-Concordant Dual Comparative Medial Branch Blocks. Pain Med 2020;21(5):902–909 — https://pubmed.ncbi.nlm.nih.gov/31609391/
Manchikanti L, Kaye AD, Soin A, et al. Comprehensive Evidence-Based Guidelines for Facet Joint Interventions in the Management of Chronic Spinal Pain: ASIPP Guidelines. Pain Physician 2020;23(3S):S1–S127 — https://pubmed.ncbi.nlm.nih.gov/32503359/
Dreyfuss P, Halbrook B, Pauza K, et al. Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysial joint pain. Spine 2000;25(10):1270–1277 — https://pubmed.ncbi.nlm.nih.gov/10806505/
Perolat R, Kastler A, Nicot B, et al. Facet joint syndrome: from diagnosis to interventional management. Insights Imaging 2018;9(5):773–789 — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6206372/
National Institute of Arthritis and Musculoskeletal and Skin Diseases: Back Pain — https://www.niams.nih.gov/health-topics/back-pain

SpecialtyPain ManagementTypeProcedureBody locationLumbar facet joints, L3-L4, L4-L5, L5-S1, lumbar medial branch nerves, dorsal ramusCPT code64493 (lumbar/sacral, single level), 64494 (second level, add-on), 64495 (third level and beyond, add-on); 77003 (fluoroscopic guidance, when reported separately)

Also called Lumbar MBB, Medial Branch Nerve Block, Facet Nerve Block, Lumbar Facet Block

This page is for general education and is not a substitute for medical advice. Whether a given procedure is appropriate depends on your individual evaluation. Contact a Remix Medical clinician to discuss your care.

Updated July 9, 2026. Medically reviewed by Raju Mantena, DO.