Medial Branch Blocks

What is a medial branch block?

At times, it becomes quite difficult for your provider to determine what is causing the pain in your low back, legs, or your neck or arms. Frequently through history, examination, and review of your X-rays, MRI or CT scan, a pain generator can be identified. Once a pain generator has been identified, decisions can be made regarding how best to treat it. Diagnostic blocks are tests meant to decrease your pain temporarily and to define it more precisely.

Questions? If you have questions regarding the information you have read here, ask our staff for further information. Additional links are provided for more detailed information.

Patient Information



Pain and Anatomy:

Pain which is mostly in the back or neck may be coming from one or more of the little guiding joints in the lumbar or cervical area of the spine. These joints are called FACET JOINTS. Just as a joint in your finger, shoulder, or elbow can give you discomfort, so can facet joints in your back. This is a type of “mechanical low back pain” or “mechanical neck pain” and has certain characteristics, which can be identified from your history and physical. In addition, an X-ray, MRI or CT scan might suggest some “wear and tear” or arthritis in these joints.

Initial treatment is usually physical therapy (instructions in exercise, posture, and body mechanics). However, it is possible to block the nerve going to each of these joints to see if the pain can be reduced. If a significant decrease is obtained through the temporary block, there is the possibility a longer lasting block of the nerve, using a radiofrequency probe, could lessen the overall discomfort.

What to Expect:

The test is done by a physician in the surgery suite, using fluoroscopy (a visual X-ray process). Fluoroscopy is used to guide the placement of the needle used to inject a local anesthetic. You are awake throughout the procedure. After the injection site is prepared with an antiseptic solution. A small needle is inserted to place additional anesthetic near each of the facet joints to block the tiny facet nerve. During the injection there may be some pressure or pain in the back.

Make arrangements to have a responsible adult accompany and drive you home. This is for your safety and the safety of others.

The Risks:

The potential risks for medial branch blocks are the same as for any procedure involving needle placement.

They include:

  • Allergic reaction to the local anesthetic (you will be asked to reveal any known allergies prior to the procedure).
  • Infection (this risk is minimized by performing the procedure within the surgery suite using sterile technique).
  • Injury to nerve (numbness or muscle weakness).
  • A temporary increase in pain at the injection sites.

Pre-Block Instructions:

  • DO NOT take your pain medication for at least six (6) hours prior to your scheduled block. Since the purpose of performing the block is to identify and evaluate the structures that influence your pain, taking your pain medication may mask the symptoms usually present.
  • Nothing to eat or drink two (2) hours prior to appointment.
  • Be as active as tolerated.
  • In the event that your usual pain is not present the day of the procedure, please call the Surgery Center to reschedule the block for another day.
  • If you are on blood thinners please contact the clinic where your procedure is scheduled and notify them that you are taking anticoagulants. In order to have the procedure, you will need to check with your primary doctor for approval to be off your medication at least 3-7 days prior to the procedure. Patients on Coumadin require a protime/INR blood test the day before the procedure with an acceptable value of 1.5 or below. Bring these results with you to your appointment.

Your Responsibility After the Block:

After the blocks are completed, the staff will ask you to get up and move around to see if there is any change in your usual pain. You will be asked to keep a record of your pain over the next few hours. The combination of how the pain changes and how long the relief lasts will help your doctor decide if you are a candidate for radiofrequency.

Summary: If there is no change in your pain, then attention will be directed to other possible sources of pain. If your symptoms improve significantly, additional blocks will be performed later to confirm the diagnosis. If no significant change occurs, your pain is likely to be coming from other structures.
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