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.
The medial branch block is often used as part of a 2-step diagnostic and treatment approach:
Role of 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.
Role of a Medial Branch Radiofrequency Neurotomy (Ablation)
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.
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Facet Joint Injections
At times, a medial branch block is tried after the patient has already been treated with one or more facet joint injections, although this is not always the case.
Facet joint injections involve an injection of anti-inflammatory steroid solution directly into the joint. If such an injection confirms the facet joint as the likely source of the patient's pain, but this injection - along with other treatments (such as physical therapy, manual manipulation, and medications) have not resulted in long term pain relief, then a medial branch block may be recommended.
As evidence evolves on the efficacy of facet joint injections, a medial branch block may also be considered instead of a facet joint injection. A medial branch block might also be considered first if for any reason the patient cannot tolerate the steroid and/or an injection directly into the facet joint.