Medial Branch Blocks

Medial Branch Block

What is a medial branch block?

Facet joints are the small joints between each of the vertebrae in your spine. Medial branches are small nerves that transmit pain signals from the facet joints to the brain and allow you to feel pain from the joints. If the facet joints are causing your pain, stopping the pain signals from the joints will temporarily relieve your pain. A medial branch block is an injection to numb the nerves so they can no longer transmit pain signals from the joint. This is similar to the dentist numbing the nerve in your mouth before working on a painful tooth.

Medial branch blocks are for diagnosis only and are not for permanent pain relief. The procedure will help your doctor determine if the facet joints are causing all or most of your pain. If you get significant (80% or more) pain relief it is considered a positive block. If you do not get relief then the block is negative and you are not having pain from the facet joints.

Does it work?

If the facet joint is the source of pain, you should experience 80% or more pain relief within 30 minutes after the injection, which may last for a few hours or longer. If the injection is positive, the injection is usually repeated to confirm that the joints are most likely causing pain. (Many insurance companies require the second medial branch block). If facet joints are confirmed as a source of pain, you will be offered a longer lasting non-surgical treatment called radiofrequency lesioning (RF). RF can provide 6-12+ months of relief by using heat to disable the medial branch nerves.

What will happen during the procedure?

You will be lying face down and your skin will be cleaned. Using x-ray guidance a thin needle will be carefully directed to the medial branch nerve. Next, a small amount of numbing medicine will be injected over the nerve. Two medial branch nerves supply each joint, and each nerve will be injected separately. The procedure is generally well tolerated.

What happens on the day of my appointment?

  • If you have uncontrolled high blood pressure, fever or active infection, we will not be able to do the procedure
  • You can eat and drink normally
  • If you are on blood thinners (Coumadin, Plavix or others) you must alert your doctor. If you are on Coumadin, you will need to have an INR checked before the procedure.
  • Take other medications as normal. Bring a list of your medications with you.
  • You will be asked to sign a consent form. The doctor will be able to answer any questions you may have at this time.
  • After you have had your procedure, you will need to stay for about 15 minutes before being discharged.

What do I do after the procedure?

Before you leave, you will be given a pain log to fill out over the next 5 hours. You need to make sure you are doing activities that normally cause you pain and then mark your pain level compared to your “normal” pain. It is VERY important that you try to reproduce your normal pain frequently during the 5 hours because it is the only way that you and your doctor will know if the injection relieves your pain.


  • More discomfort for the first few days after your injection
  • Bruising to the injection area
  • Nerve injury-very rare
  • Allergy to injected medication – very rare
  • Infection – very rare

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