Lumbar Medial Branch Blocks

A straightforward Guide for Patients

What is a Lumbar Medial Branch Block?

Arthritis of the facet joints is a very common cause of lower back pain. These small joints help guide movement of the spine—allowing you to bend, twist, stand, or walk comfortably. When these joints become irritated or arthritic, everyday movements can trigger significant pain.

Each facet joint sends pain signals to the brain through a tiny nerve called the medial branch nerve. By temporarily numbing this nerve with a local anesthetic, we can determine whether the facet joints are the true source of your pain.

A medial branch block is diagnostic, meaning it helps identify the cause of your pain and determines whether you may benefit from radiofrequency ablation (RFA), a longer-lasting treatment that can relieve pain for 9–12 months.

Purpose of the Injection

Medial branch blocks help answer one key question:

Is your low back pain coming from arthritic or inflamed facet joints?

During the procedure:

  • A small amount of numbing medication is placed directly on the medial branch nerve.
  • If the facet joints are the source of your pain, you should feel noticeable relief while the nerve is temporarily blocked.

Your response helps guide the next steps in your treatment plan and determines whether you qualify for RFA.

How the Procedure Works

  • You will be positioned face-down in a sterile procedure suite.
  • The skin over the targeted area is cleaned and numbed with local anesthetic.
  • Using X-ray guidance, the provider places a small needle over each medial branch nerve being tested.
  • A small amount of anesthetic is injected at each site.
  • Afterward, you will be monitored briefly in recovery and then discharged home.

The procedure is typically quick and well-tolerated.

After the Injection

Follow the personalized instructions provided at discharge.

General Guidelines

  • Resume usual activities as tolerated.
  • You are encouraged to perform movements that normally increase your pain—this helps determine how effective the block was.
  • Showering is allowed, but avoid baths, lakes, pools, and hot tubs for 24 hours.
  • Keep track of your symptoms in the hours following the injection.
  • The care team will call you to review your results.
    • If you experience significant temporary relief, you may qualify for:
      • A second diagnostic block (if required by insurance), or
      • Radiofrequency ablation, the next step for longer-lasting relief.

If Sedation Was Used

  • No solid foods for 8 hours prior.
  • Clear liquids allowed up to 2 hours before
    (water, broth, pulp-free juices, black coffee/tea; no carbonated drinks).
  • No gum, candy, mints, or lozenges within 2 hours.
  • The care team will review your medications beforehand and provide specific instructions.

Failure to follow these guidelines may require rescheduling.

Risks and Possible Side Effects

Medial branch blocks are considered safe and minimally invasive, but potential risks include:

  • Temporary soreness at the injection site
  • Minor infection (rare)
  • Increased usual pain
  • Bleeding or bruising, especially if you take blood thinners
    (please notify us if you take Plavix, aspirin, Xarelto, warfarin, rivaroxaban, heparin, Lovenox, Brilinta, or similar medications)
  • Very rare nerve or spinal cord injury
  • Dural puncture / spinal fluid leak, which may cause a positional headache
  • Allergic reaction to local anesthetics or contrast dye
  • Extremely rare complications such as epidural fibrosis, aseptic meningitis, GI or renal issues, seroma, or paralysis
  • Inability to complete the injection due to anatomical variations

Your provider will discuss any individualized risks before treatment.