Lumbar Medial Branch Blocks (Facet Nerve Injection)

Diagnostic injections can help the doctor to identify the cause of pain, therefore, making the plan of treatment more focused and more effective. Finding a specific diagnosis leads to better treatment and better outcomes for the patient.

The Facet Joints and Medial Branch Nerves
The facet joints are the small joints between the vertebral segments on both sides of the spine. Each vertebral segment has two facet joints, one on each side. These joints provide stability and control for bending and twisting. Pain in the low back with a less specific, vague aching in the legs (one or both) may be caused by injury or osteoarthritis of the facet joints.

If you obtain pain relief while your medial branch nerves are anesthetized, then your doctor knows your pain is facet joint related.


The Purpose of Medial Branch Blocks
A local anesthetic is used to temporarily try to block these nerves from sending the pain signals on to the brain. If you have pain due to facet joint arthritis, you may feel relief of that pain for a few hours.

If significant pain relief is obtained through this temporary block, then you may be a candidate for a more long-lasting block of the nerves called medial branch radiofrequency neurotomy. Medial branch blocks are often used as a test to determine if radiofrequency neurotomy may help reduce your pain.

The Procedure
The patient is placed in the prone (lying face down) position with a pillow underneath the abdomen. The skin of the low back is sterilely prepared. Using fluoroscopic (X-ray) guidance, the bony landmarks are viewed. The skin is anesthetized. Under fluoroscopic guidance, thin needles are advanced to the appropriate area for medial branch blockade. A small volume of contrast solution is injected to prove that the medication will stay in the appropriate area. Then, a small volume of long-acting anesthetic is injected. The patient is cared for in the recovery area for 20 minutes.

Preparing for Medial Branch Blocks

  • For a diagnostic injection, you should have some pain at the time of your procedure or be able to consistently reproduce it with certain activities. If you are typically pain-free after taking pain medication, please do not take these medications for 4 to 6 hours before the injection.
  • There are no special dietary instructions for this procedure unless it includes sedation.
  • While the procedure may take less than 15 minutes, you should allow for at least 1 hour at the procedure center.
  • You need to arrange for a driver to be present and take you to and from the medical facility. If you do not have a driver with you, your procedure may have to be rescheduled.
  • Inform your doctor’s secretary if you have a pacemaker.
  • If you develop a fever, night sweats, or an active infection, your procedure will need to be rescheduled. Please contact our office at (651) 968–5201 immediately to inform us of your change in condition.

After the Injection
After the procedure, you should try to gently reproduce your pain and inform your care team of the percentage of relief you obtained from the injection.

Potential Risks of Medial Branch Blocks
The risks are quite minimal, but are similar to any procedure involving a needle placement. These include, but are not limited to:

  • Allergic reaction to the anesthetic or X-ray dye. Be sure to inform us before the injection if you have any known allergies.
  • Infection.
  • Temporary pain at the injection site.

If Your Procedure Includes Sedation

  • You should have no solid foods for 6 hours before your procedure.
  • You may have clear liquids up to 2 hours before your procedure. Examples include: water, broth, clear fruit juices such as apple, cranberry, and grape juice. These juices should not include pulp. Tea, black coffee with no cream, and carbonated beverages are also allowed.
  • Nothing by mouth, including throat lozenges, mints, and all hard candy.
  • No gum for 2 hours before your procedure.
  • You must have a responsible adult arrive with you to our facility. If you use a taxi or volunteer ride service, you still must have a responsible adult with you in order to help take care of you after your sedation procedure.
  • Please take your regular medications the day of your procedure, especially any heart or blood pressure medications.
  • If you are on medication for diabetes, be sure to take it the day of the procedure.

Also see...