Medial Branch Block

A medial branch block is used to find out whether your back or neck pain comes from the facet joints. It temporarily numbs the small nerves that carry pain from those joints. If your usual pain drops sharply for a few hours, the facet joints are the likely cause, and radiofrequency ablation of the same nerves may give relief that lasts much longer^[1].

Most people describe it as mildly uncomfortable rather than painful. The skin is numbed first, and the needles used are thin. You may feel pressure or a brief ache as each needle is positioned. Afterward the injection sites can be sore for a day or two, which usually responds to ice and over-the-counter pain relievers.

The relief from a diagnostic medial branch block is meant to last only as long as the numbing medicine — usually a few hours, depending on whether a short- or longer-acting anesthetic is used. A short result is not a failure: the test is judged by how much your pain improves during that window, which is why you keep a pain diary for the rest of the day.

It is worth it if you are considering radiofrequency ablation for facet joint pain. Guidelines and Medicare both use medial branch blocks to decide who is likely to benefit from ablation, so the block protects you from having an ablation that is unlikely to help^[1][2]. If your pain is mainly sciatica or arm pain, a different test or treatment is usually a better choice.

A single block can give a false-positive result, for example from a placebo effect. Requiring two separate blocks on different days that both give strong relief makes the diagnosis more reliable. Medicare in New York requires two diagnostic blocks, each providing at least 80% relief of your usual pain, before it covers radiofrequency ablation^[2].

Do the activities that normally cause your pain — within reason — and record your pain level every hour or so for six to eight hours. Avoid strenuous exercise that day. Arrange a ride home if you received any sedation. Most people return to normal activities, including work, the next day. Call us if you develop fever, increasing pain or new weakness.

If you had no sedation and your legs or arms feel normal, many patients can drive, but we recommend bringing a driver the first time because temporary numbness can occur. If you receive any sedation, you must not drive for the rest of the day.

Not necessarily. Medial branch blocks are classified as low bleeding-risk procedures in interventional pain guidelines, so many patients continue their medicines^[3]. The decision depends on which blood thinner you take and why, so never stop one on your own — we will coordinate with the doctor who prescribed it.

No. A facet joint injection places medicine, often a steroid, inside the joint for relief. A medial branch block numbs the nerves that serve the joint and is mainly a test. Some physicians add a small amount of steroid to a block, but a purely diagnostic block uses only a local anesthetic^[5].

A negative block is useful information: it suggests the facet joints are not the main source of your pain, so ablation of those nerves is unlikely to help. Your physician will look at other sources, such as the discs, the sacroiliac joints or a pinched nerve, and may recommend a different test or treatment such as an SI joint injection or an epidural steroid injection.

Medicare and most commercial plans cover medial branch blocks when coverage criteria are met, such as at least three months of facet-type pain that limits daily activities and has not improved with conservative care^[2]. Prior authorization is often required. Workers’ compensation and no-fault claims follow their own rules. Our staff will verify your benefits before scheduling.

Serious complications are rare. The most common side effects are temporary soreness at the injection sites and brief numbness or weakness from the anesthetic. Infection, bleeding and allergic reactions are uncommon^[5]. Because X-ray is used, tell us if you might be pregnant.