Updated: Dec 20, 2019
A medial branch block is an injection of a strong local anesthetic on the medial branch nerves that supply the facet joints, and is often used as part of a two-step diagnostic process. If the patient experiences the appropriate amount of pain relief after the injection, then the facet joint is determined to be the primary source of pain and the patient can then be considered a candidate for a subsequent treatment that will provide longer term pain relief.
The facet joints, also known as the zygapophysial joints, are part of the framework of the spine. They are small projections from one vertebra meeting with similar bony projections from the vertebra above or below. Sometimes, due to a variety of acute and chronic conditions, the facet joints can become inflamed. For lower back (lumbar) facet joints, the pattern of pain is usually an achiness in the low back, radiating across the lower back and slightly down the back of the buttocks and upper thighs. Usually, standing or bending backward worsens the pain. For neck (cervical) facet joints, the pattern of pain is an achiness in the neck, slight radiation across the neck and shoulders, and worsening symptoms with turning the head from side to side or looking up.
Rationale for Need of Treatment
Medial branch blocks are suggested for patients with chronic, difficult to treat, axial spine pain that is inadequately explained and poorly controlled.
Procedure of Medial Branch Block
The injection consists of a small amount of long acting local anaesthetic. The procedure begins by injecting a small amount of local anaesthetic through a very small needle. It feels like a little pinch and then a slight burning as the local anaesthetic starts numbing the skin.
It is typically done with you lying on your stomach for back injections and on your side for neck injections. Your blood pressure and oxygenation will be monitored. The skin on the back is cleaned with antiseptic solution and then the procedure is done. Very small needles are placed along the bony landmarks that mark the location of the medial branch nerves. A small volume, usually about 0.3 mL, is injected along each nerve.
Shortly after the injection, you may notice that your pain may be gone or considerably less. This is due to the effect of the local anaesthetic and lasts only for a few hours to a few days.
The physician will then ask the patient to perform some movements or activities that would usually provoke the pain. This assessment is done in order to determine if the medial branch nerve block has reduced the patient's pain. If you do not obtain reasonable relief from this diagnostic injection, it is unlikely you will obtain relief from radiofrequency lesioning. Your doctor will discuss this with you.
Recovery After Treatment
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 targeted are the ones carrying signals for their pain. If the joint or joints being targeted are not causing the pain, a patient will not obtain relief from the medial branch nerve block.
Ideally, patients will also record the levels of pain relief during the next several hours in a pain diary. Maintaining the pain diary is helpful to clearly inform the treating physician of the injection results and in planning future tests and/or treatment, as needed.
Patients may continue to take their regular medications after the procedure, with the exception of limiting pain medicine within the first 4 to 6 hours after the injection so that the diagnostic information obtained is accurate. Thus, patients may feel complete (almost 80% recovery) or partial pain relief during the first 4 to 6 hours after an injection.
Can you go back to work the same day or the next day? Your doctor or recovery room nurse will discuss the specifics with you, but typically you should be able to unless there were complications with the procedure. That being said, patients are advised to take it easy for a few days and only perform light, minimally impactful daily activities.
Possible Risks and Side Effects
As with all invasive medical procedures, there are slight potential risks and complications associated with medial branch blocks. However, in general, the risk is low, and complications are rare. Commonly encountered side effects are increased pain from the injection (usually temporary), infection, bleeding, nerve damage, or allergic reactions. 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.
Consulting at Northern Arizona Pain Institutes
Before moving forward with a procedure like medial branch block, you should always consult a professional to discuss other options, possible risks and side effects, long-term effects, and any other questions you may have. Northern Arizona Pain Institutes’ team of highly qualified professionals can be a helpful resource when considering any type of pain-reducing treatments. Please visit our website to learn more about procedures or to book an appointment: www.NAZspineandPain.com.