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Procedure: Medial Branch Block


What is a Medial Branch Nerve Block (MBB)?

It is a procedure that is designed to interrupt the pain signals being carried by the medial branch nerves.  The medial branch nerves are found near facet joints and transmit pain signals from that area to the brain.


What conditions are treated with a medial branch nerve block?

The procedure can be used to help patients with chronic (long lasting) lower back/neck pain and pain related to the degeneration of joints from arthritis. It also helps to confirm that the facet joint is the source of a patient’s pain so that a radiofrequency medial branch neurotomy (ablation) may be considered for longer term pain relief.


How long does the procedure take?

The injection itself only takes a few minutes, but the entire procedure usually takes between fifteen and thirty minutes depending on how many areas are being blocked. The patient should plan to be in the office for one to two hours, this allows for patient's pre-op and recovery time as well. 


How long does the procedure last?

Patients may feel complete or partial pain relief during the first 6 to 12 hours after an injection. After the injection wears off, the pain may return to the pre-procedure level or increase for a short time.  Remember, this is used more as a diagnostic tool to determine which nerves are affected.


Will I be “Put Out” for this procedure?

Generally, an IV line is not started for this procedure due to not wanting to get false positives/feedback from the patient after the procedure. Most of the time, if a patient has an IV it will be hard to determine if the patient feels relief with the injection or the IV sedation.


How is the procedure performed?

As with many spinal injections; medial branch blocking procedures are best performed under fluoroscopy (live x-ray) for guidance in properly targeting and placing the needle. It is also used for avoiding nerve injury or other injury. The patient lies on an x-ray table, and the skin over the area to be tested is well cleansed. The physician treats a small area of skin with a numbing medicine (anesthetic), which may sting for a few seconds.  Several drops of contrast dye are then injected to confirm that the medicine only goes over these medial branch nerves. Following this confirmation, a small mixture of numbing medicine (anesthetic) will then be slowly injected onto each targeted nerve.


What should I expect after the procedure?

After the procedure, the patient is asked to move the affected area and be active to try to provoke the usual pain. Patients may or may not obtain pain relief in the first few hours after the injection, depending upon whether or not the medial branch nerves that were injected are carrying pain signals from the spinal joints to the brain. On occasion, patients may feel numb or have a slightly weak or odd feeling in their neck or back for a few hours after the injection.


The patient will be asked if they feel any immediate pain relief. They will also be asked to record the levels of pain relief in a pain diary for several hours the day of the block. A pain diary is helpful to clearly inform the physician of the injection results and helps planning of future tests and/or treatment, as needed.


If the area is uncomfortable in the first two to three days after the injection, patients are advise to apply ice or a cold pack to the general area of the injection site will typically provide pain relief. 


What are the risks and side effects? 

As with all invasive medical procedures, there are potential risks and complications associated with medial branch blocks. However, in general the risk is low, and complications are rare. Potential risks and/or complications include slight risk for infection, bleeding, nerve damage and worsening of pain. The main side effect is discomfort, including swelling and bruising at the injection site, but this generally goes away after a few days.


Who should not have this procedure done?

The patient should not have this procedure if they have an active infection, are pregnant or think they might be pregnant, or weigh over 390 pounds.

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