How Can Medial Branch Blocks Help Your Back Pain?

Medically reviewed by Stuart Hershman, MD

Medial branch blocks have an important place in back pain medicine. According to E-Medicine, several experts believe that problems in the facet joint underlie most cases of mechanical low back pain (possibly 80%).

Understanding your anatomy can be helpful in understanding this back pain and its treatment. There are two facet joints in each segment, and together they provide an estimated 36% of the spine's stability for that segment, while at the same time facilitating certain types of movement. Facet joints are also known as the zygapophyseal joints or Z-joints.

The medial nerve lives just outside of and innervates the facet joints. It is also one of three branches of a larger nerve called the dorsal ramus, which is the first subdivided nerve arising from the spinal nerve root. Remember, dorsal means back and ramus means branch.

The three nerves branching from the dorsal ramus serve many areas, including key back muscles. The medial branch in particular affects the facet joint itself as well as deep back muscles such as the interspinales, the multifidus, and a few others. The medial branch also reaches into at least one spinal ligament (the interspinous) and possibly two (the ligamentum flavum as well).

What Are Medial Branch Blocks?

When you have a medial branch block, a local anesthetic such as lidocaine is injected into the medial nerve of the facet joint. Injecting the local anesthetic into the medial nerve helps healthcare providers diagnose back pain. If the injection relieves at least 50% of your usual back pain, your healthcare provider will likely confirm that the pain is coming from the facet joint and recommend radiofrequency ablation as treatment. Medial branch blocks are also used to diagnose sacroiliac joint pain.

You can have a medial branch block on just one side of the facet joint or on both. When both sides are treated, it is called a bilateral injection.

Medial Branch Blocks or Intra-Articular Injections

Another type of injection used to diagnose back pain is the intra-articular injection. This injection goes right into the facet joint space which is surrounded by a capsule made of tough fibrous tissue. A 2012 study published in the journal Pain Physician found, among other things, that the association between medial branch blocks and successful facet joint treatment may be greater than the one between intra-articular injections and successful treatment. That said, the authors call for additional high-quality studies to be done on the subject before they can confirm this finding.

Medial Branch Blocks as Treatments

While most of the time the medial branch block is given for diagnostic purposes, it is also sometimes used as a therapy.

A 2013 study published in the Annals of Rehabilitative Medicine found that for people who had medial branch blocks for chronic facet joint pain related to osteoporotic fracture following either vertebroplasty or conservative treatment, the outcomes were good a year post-injection. The authors say that medial branch block yielded pain relief and functional recovery for these patients.

But a 2012 study that evaluated various thoracic facet joint treatments found only fair evidence for medial branch blocks as a way of relieving chronic pain in that area. That said, researchers were not even able to compare medial branch blocks with intra-articular injections, because there was no evidence at all for the intra-articular treatments. And the PM&R study mentioned above aside, only limited evidence was found for radiofrequency neurotomy. The use of radiofrequency ablation and/or neurotomy is more common for facet joint pain treatment than medial branch blocks.

Radiofrequency ablation is an outpatient procedure in which heat is applied to the nerves around the facet joint, killing the cells. Over time, the body replaces the dead nerve cells with scar tissue. Even though radiofrequency ablation is considered a controversial treatment, ablation in lumbar facet joints may provide longer lasting pain relief than in other areas of the spine. A 2015 study published in the International Journal of Anesthetics and Anesthesiology found that two years post lumbar spine radiofrequency ablation, patients were doing well in terms of pain management, ability to function, and how much pain medication they needed.

In a neurotomy, the same type of heat—from radiowaves—is applied in order to temporarily relieve the pain. A 2012 study published in the journal PM&R (Physical Medicine and Rehabilitation) found that pain relief resulting from radiofrequency neurotomy procedures lasted between seven to nine months for most patients, and this was true whether the treated area was in the neck or the low back.

What Happens in a Medial Branch Block?

The procedure will most likely take place in an outpatient facility and you will not be put to sleep. The healthcare provider will start by giving you a shot of a local anesthetic to numb your skin and the tissue near the facet joint. You’ll lie on your stomach to enable the healthcare provider to reach your facet joints, which are located at the back of the spinal column.

Then the healthcare provider will insert a needle that is hooked up to a camera called a fluoroscope into the facet joint area. Through the needle, contrast dye will be injected into the area. This enables the healthcare provider to see whether or not the numbing agent to be used covers the entire area around the facet joint. Next, the anesthetic is injected into the joint.

Once the anesthetic has been injected, your healthcare provider may direct you to perform the same moves that normally bring on your pain or symptoms. According to Alex Vaccaro, MD, professor of neurosurgery and orthopedic surgery at Thomas Jefferson University in Philadelphia and co-director of their Spinal Cord Injury Center, between 50% and 75% pain relief will give your healthcare provider a reason to confirm that your back pain is coming from your facet joint and/or your medial branch nerve.

Because each facet joint is supplied by two medial branch nerves (one from the vertebra above and one from the vertebra below) you’ll likely receive two shots of anesthetic for every facet joint marked for treatment.

This can make for confusion when it comes to medical coding and billing. In fact, in recent years, facet joint injection documentation problems have led to a substantial degree of Medicare fraud.

Medicare Fraud and Abuse Relating to Facet Injections

Before a physician can prescribe a medial branch block to a Medicare recipient, the physician must determine that the treatment is medically necessary. A physician that bills Medicare for a treatment without complying to Medicare requirements may be committing fraud, waste, or abuse of Medicare resources.

In 2023, the US Department of Health & Human Services conducted an audit of 120 cases in which facet joint treatments were given. Among them, 66 treatment sessions were not in compliance with Medicare requirements.

Using data from the audit, the department estimated that Medicare improperly paid physicians $30 million for spinal facet joint interventions between August 2021 and October 2021 alone.

Medicare fraud diverts resources away from those who need them, lines the pockets of wrongdoers instead, and places you at risk for receiving treatments you don't need. Unfortunately, facet joint interventions like medial branch blocks have a high risk for being over-prescribed.

You can help prevent fraud by reviewing your Medicare coverage carefully and understanding what is and is not covered. If you feel that your provider is pressuring you to get a medial branch block and you are unsure if it is covered or necessary, turn the treatment down and get a second opinion from another physician.

Read the original article on Verywell Health.