Medial Branch Blocks Specialist

What are Medial Branch Nerves?

Facet joints are pairs of small joints that are situated at each vertebral level of the spine. A facet joint may also be called a zygapophysial joint or a Z-joint. Medial branch nerves are small nerves that feed out from the facet joints in the spine and carry pain signals from the facet joints to the brain. Each facet joint is connected to two medial nerves.

The medial nerves are uniquely located in each segment of the spine:

• Cervical medial branch nerves are located in a bony groove in the neck
• Thoracic medial branch nerves are located over a bone in the mid-back or upper back
• Lumbosacral medial branch nerves are found in a bony groove in the low back

What is a Medial Branch Block?

A medial branch nerve block is a procedure in which an anesthetic is injected near small medial nerves connected to a specific facet joint. Typically several levels of the spine are injected in one procedure. If the patient experiences marked pain relief immediately after the injection, then the facet joint is determined to be the source of the patient's pain. The procedure is primarily diagnostic, meaning that if the patient has the appropriate duration of pain relief after the medial branch nerve block, then he or she may be a candidate for a subsequent procedure - called a medial branch radiofrequency neurotomy (or ablation) - for longer term pain relief.

As with many spinal injections, medial branch nerve block procedures are best performed under fluoroscopy (live X-ray) for guidance in properly targeting the nerves, placing the needle, and avoiding injury. 

What can you expect during a Medial Branch Block?

The medial branch injection procedure includes the following steps: 

• Commonly, the procedure is performed with the patient awake, or with only slight
• The patient lies face down on a procedure 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
• The physician uses X-ray guidance (fluoroscopy) to direct a very small needle over the medial branch nerves
• Following this confirmation, a small amount of numbing medicine (anesthetic) will then be slowly injected onto each targeted

The injection itself only takes a few minutes, but the entire procedure usually takes between fifteen and thirty minutes. 

After the procedure, the patient typically remains resting in the recovery area for 20 to 30 minutes. 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. 

What are the risks of a Medial Branch Block? 

Potential risks and/or complications that may occur from a medial branch injection include: 

• Allergic reaction. The potential allergy is usually to the X-ray contrast solution and rarely to local anesthetic
• Bleeding. A rare complication, bleeding is more common for patients with underlying bleeding disorders
• Infection. Minor infections occur in less than 1% to 2% of all Severe infections are rare, occurring in 0.01% to 0.1% of injections
• Worsening of pain symptoms
• Discomfort at the point of the injection
• Nerve or spinal cord damage or paralysis. While very rare, damage can occur from direct trauma from the needle, or secondarily from infection, bleeding resulting in compression, or injection into an artery causing

Depending on the amount of pain relief the patient has during the first 4 to 6 hours after the injection, the patient may be a candidate for a radiofrequency neurotomy (radiofrequency ablation) procedure to try and provide longer term pain relief. Generally, a patient must report at least 80% improvement in their pain during the first 4 to 6 hours after the injection to be considered a candidate for radiofrequency neurotomy.

When is a Radiofrequency Ablation indicated?

In cases where a medial branch nerve block has confirmed that a patient's pain originates from a facet joint, a radiofrequency neurotomy can be considered for longer term pain relief. A radiofrequency neurotomy is a type of injection procedure in which a heat lesion is created on the nerve that transmits the pain signal to the brain. The goal of a radiofrequency neurotomy is to interrupt the pain signal to the brain, while preserving other functions, such as normal sensation and muscle strength.