Sacroiliac Joint Nerve Block

OVERVIEW

What a sacroiliac joint nerve block is and how it works

The sacroiliac joints sit where the base of the spine (sacrum) meets the pelvis. The back portion of each joint is supplied by small nerves called the lateral branches of the sacral nerves. A sacroiliac joint nerve block — also called a lateral branch block — places a small amount of local anesthetic onto these lateral branch nerves to interrupt the pain signals they carry.

This procedure is primarily diagnostic. If your usual SI joint pain drops significantly during the hours that the anesthetic is working, it points to these nerves as a likely pathway for your pain. Because a single block can occasionally give a false-positive result, your physician may repeat the block on a separate visit to be more confident before recommending longer-term treatment.

A good response also helps your physician decide whether you may be a candidate for sacroiliac joint radiofrequency ablation — a longer-lasting treatment that interrupts the pain signals from these same nerves. Unlike a sacroiliac joint injection, which delivers medication inside the joint itself for both diagnosis and relief, a nerve block targets the nerves outside the joint rather than the joint space.

At Columbia Pain & Spine Institute, our dual board-certified, fellowship-trained physicians perform these blocks under live image guidance to map your pain precisely before recommending any longer-term procedure.

YOUR VISIT

What to expect

Arrange for someone to drive you home if you receive any sedation. Many patients resume normal activity the following day. Tell us right away about fever, spreading redness, severe new pain, or new weakness — these are uncommon but should be evaluated promptly.

QUESTIONS

Frequently asked questions

Is a sacroiliac joint nerve block a cure for my pain?

No. This block is mainly a diagnostic test. Its goal is to confirm whether the lateral branch nerves are carrying your SI joint pain. The relief from the anesthetic is temporary. If your pain improves substantially, you may be a candidate for radiofrequency ablation, which is designed to provide longer-lasting relief by treating those same nerves.

How is this different from a sacroiliac joint injection?

A nerve block targets the lateral branch nerves outside the joint, while a sacroiliac joint injection places medication inside the joint itself. Your physician may use one or both to help pinpoint the source of your pain and guide treatment.

What happens if the block works well?

A clear, temporary reduction in your usual pain points toward the SI joint nerves as a source. A common next step is a discussion about radiofrequency ablation; in some cases, surgical options such as sacroiliac joint fusion may be considered. Your care plan is always individualized.

Does the block require sedation?

Usually not. The skin is numbed first, and most patients feel only brief pressure during the injection. If light sedation is used, you should arrange a ride home and avoid driving that day.

NEXT STEPS

Talk with our team in Gresham and Portland