Medial Branch Blocks and Facet Injections

A short test that shows whether arthritic facet joints are causing your back or neck pain, and whether longer-lasting radiofrequency ablation is likely to help.

Mountain Home870-706-2557
Harrison870-233-9960

What is facet joint pain?

The facet joints are small paired joints along the back of the spine that guide how it bends and twists. Like other joints, they can develop arthritis, and they are a common source of chronic low back and neck pain.1

Facet pain is usually an ache across the low back or neck, sometimes spreading into the buttocks, hips, or upper thighs, or into the shoulders from the neck. It often feels worse with standing, arching backward, or twisting, and better with sitting or lying down.

Each facet joint sends pain signals through small nerves called medial branches. Imaging can show arthritis, but it can’t show whether a joint is actually causing your pain. That’s what a medial branch block tests.1

Illustration of a lumbar facet joint and the small medial branch nerve that carries its pain signals
The medial branch nerves carry pain signals from the facet joints.

How a medial branch block works

A small amount of numbing medicine is placed next to the medial branch nerves that supply the joints we suspect. If your usual pain drops a lot while the numbing medicine is working, those joints are very likely the source.

  1. Pinpoint the joints

    Your history, exam, and imaging point to the levels most likely causing pain.

  2. X-ray guided injection

    After numbing the skin, a thin needle is guided by X-ray to each target nerve.

  3. Numbing medicine

    A tiny dose of local anesthetic temporarily quiets the nerves.

  4. Check your relief

    Right after the block, you try movements that usually hurt and note how much your pain improves, and for how long.

Medial branch block or facet joint injection? A medial branch block numbs the nerves to a joint. A facet joint injection places medicine, sometimes including a steroid, inside the joint itself. Medial branch blocks are better at predicting who will benefit from radiofrequency ablation, so they are the test we usually use.1

Why two blocks?

One block can occasionally give relief even when the facet joints aren’t the main problem. A second block on a different day confirms the result.

Block 1

First test

If your usual pain improves by at least 80% for about as long as the numbing medicine is expected to last, we schedule a second block.

Block 2

Confirmation

The same nerves are blocked again on another day. A second strong response confirms the facet joints as the source.

Next step

Radiofrequency ablation

With two positive blocks, RFA can quiet the same nerves for months at a time.

Medicare and most insurance plans require two diagnostic blocks, each with at least 80% relief of your usual pain lasting about as long as the numbing medicine is expected to work, before they cover radiofrequency ablation.2 If a block doesn’t help, that is useful information too: it tells us to look for another source of your pain.

The test window is short

The numbing medicines used for these blocks, such as lidocaine or bupivacaine, wear off quickly. Relief may last only 30 to 90 minutes, depending on the medicine used. A positive block gives strong relief of your usual pain for about as long as that medicine is expected to last, and then your pain returns.1,2

  • Come in with your usual painThe test works best on a day when your typical pain is present.
  • Rate your pain beforeWe’ll ask your pain score, from 0 to 10, right before the block.
  • Test what usually hurtsRight after the block, safely try the movements that normally bring on your pain, like standing, walking, or bending.
  • Notice how long it lastsPay attention to when your usual pain starts coming back. We’ll ask how much relief you had and how long it lasted.
  • Skip extra pain medicineUnless we tell you otherwise, avoid extra pain medication on block day so it doesn’t blur the result.
  • Expect your pain to returnWhen the numbing medicine wears off, your usual pain comes back. That is normal and expected.

What to expect

Before your block

Tell us about all of your medications, especially blood thinners. We’ll tell you whether any should be paused, and please don’t stop one on your own.3 Most blocks are done without sedation, because sedation can make the test less accurate.1

During your block

You lie face down while the skin is numbed. A thin needle is guided by X-ray to each nerve. The procedure usually takes 15 to 30 minutes, and you’ll feel some pressure and brief stinging.

After your block

Pay close attention to your pain in the first hour or two, while the numbing medicine is working. Then you can resume your usual routine. Mild soreness at the injection sites is common for a day or two.

Is a medial branch block right for you?

It may be an option if

  • You’ve had low back or neck pain for at least 3 months
  • Your pain is mostly in the back or neck, rather than shooting down an arm or leg
  • It is worse with standing, arching backward, or twisting
  • Physical therapy, exercise, and medications haven’t provided enough relief

Another approach may fit better if

  • Your main symptom is pain, numbness, or weakness shooting down a leg or arm, which may respond better to an epidural steroid injection
  • Your pain started recently and hasn’t yet had a trial of conservative care
  • You have an active infection or a bleeding problem that can’t be managed safely

Common questions

Will a medial branch block fix my pain?

Not by itself. The numbing medicine wears off quickly, often within 30 to 90 minutes. Its job is to show where your pain is coming from, so that a longer-lasting treatment like radiofrequency ablation can be aimed at the right nerves. Some people do notice longer relief, which is a welcome bonus.

My pain came back within an hour or two. Did the block fail?

No. Your pain is expected to return when the numbing medicine wears off. What matters is how much your usual pain improved while the medicine was working, and whether that relief lasted about as long as the medicine is expected to.2

Why can’t I have sedation?

Sedatives can relax you and change how you perceive pain for a while, which can make a block look like it worked when it didn’t. Most people do well with just skin numbing. If you have significant anxiety or trouble lying still, talk with us about options.1

What if the block doesn’t help?

A negative block is useful. It tells us the facet joints probably aren’t your main pain source, so we can look at other causes, such as the discs, sacroiliac joints, or nerves, and choose a treatment that fits.

Can I drive myself home?

Most patients can, since blocks are usually done without sedation. Your legs or arm may occasionally feel heavy or numb for a short time, so bringing a driver is a good idea for your first block.

Will insurance cover it?

Most plans, including Medicare, cover medial branch blocks when you have had at least 3 months of pain that limits daily activities and conservative care hasn’t helped enough. Our staff will check your benefits and request any required prior authorization.2

Talk with a specialist about back or neck pain

Our physicians will review your symptoms, exam, and imaging to decide whether medial branch blocks, or another treatment, is the right next step.

Schedule a consultation

New pain management patients need a referral. Your provider can fax it to 870-706-2428.

Risks

Medial branch blocks are generally low risk. Possible side effects include soreness at the injection sites, temporary numbness or heaviness in the legs or arms, lightheadedness, bleeding, infection, and reactions to the medicine or contrast dye. Your physician will review the risks with you before your procedure. Individual results vary.

Sources

  1. Cohen SP, 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. doi:10.1136/rapm-2019-101243
  2. Centers for Medicare & Medicaid Services. Local Coverage Determination L34892: Facet Joint Interventions for Pain Management (Novitas Solutions). cms.gov
  3. Narouze S, et al. Interventional spine and pain procedures in patients on antiplatelet and anticoagulant medications (second edition). Reg Anesth Pain Med. 2018;43(3):225-262. doi:10.1097/AAP.0000000000000700

Illustration courtesy of Stryker.