Facet joints are small joints located between the vertebrae in the back of your spine, and they can be a source of back pain. One way to determine whether they are the source of your pain is to perform a medial branch nerve block injection.
Watch: Medial Branch Block Video
Our video walk-through can help you visualize this relatively common procedure.
In the image above, the facet joints, also called zygapophysial joints, are shown in purple. They are located behind the spine, and they add stability to your spine as it twists, flexes, and bends.
Medial branch nerves (pictured in purple above) are located on each facet joint. Their function is to carry pain signals to your brain.
Conditions like spinal stenosis and osteoarthritis, along with an injury to your spine, may all lead to the inflammation of your facet joints. When this inflammation occurs, your medial branch nerves transmit pain signals to your brain.
If your doctor thinks facet joint inflammation is the source of your pain, she or he may recommend a medial branch nerve block injection to help confirm the diagnosis.
How the injection works
To begin, your doctor will have you lie down on a table. She or he will then use a local anesthetic to numb the skin and tissue around your facet joint.
Using X-ray guidance called fluoroscopy (pictured above), your doctor will next steer a small needle over your medial branch nerves. Then, a small amount of contrast dye is injected to confirm the medicine covers your nerve.
Finally, your doctor will carefully inject a numbing medicine (called an anesthetic) onto each targeted nerve. Typically, two of your adjacent nerves will be targeted at the same time.
If you experience immediate and significant pain relief following the injection, it can be assumed that the source of your pain is the facet joint.
Risks and complications
Like all invasive medical procedures, there are risks associated with a medial branch block. For example, you may experience any of the following:
- Allergic reactions
- Worsening of symptoms
- Nerve damage
Thankfully, these types of complications are rare, and there are minimal risks associated with a medial branch nerve block.