Medial Branch Nerve Blocks
Last updated date: 24-Apr-2023
Originally Written in English
Medial Branch Nerve Blocks
The tiny nerves known as medial branch nerves are what allow you to experience pain in facet joints. The facet joints are tiny joints that connect each vertebra at the back of the spine. There are four facet joints on each vertebra, two on the upper or superior surface and two on the lower or inferior surface. The facet joints control how far your neck and back can be bent or twisted.
The neck and the mid or low tiny back muscles are under the control of the facet joint medial nerves. Your arms and legs don't have any muscles or sensations controlled by them. A medial branch nerve block made of steroids and anesthetic drugs might temporarily stop the pain signal originating from a certain facet joint if it has been determined that your discomfort originates from the facet nerves of certain facet joints.
What are Medial Branch Nerves?
The little nerves that transmit pain signals to the brain for the facet joints are called medial branch nerves. At each level of the spine's vertebrae are a pair of tiny joints called facets. Another name for a facet joint is a zygapophysial joint or a Z-joint. Two medial nerves are connected to each facet joint, and these nerves send pain signals from the spine to the brain. Each spinal segment has a specific area for the medial nerves:
- There is a bony groove in the neck where the cervical medial branch nerves are placed.
- The mid-back or upper back is where the thoracic medial branch nerves are situated, over a bone.
- In a bony groove in the lower spine are the lumbosacral medial branch nerves.
The goal of the medial branch nerve block is to prevent the nerves from sending pain signals to the brain, which will then determine or diagnose whether the patient's pain is coming from one or more facet joints.
There is no risk of a medial branch block adversely affecting the arms or legs or other pain-sensing mechanisms because these medial branch nerves do not control any major muscle groups or carry any sensation in those areas. Although the neck, mid, and lower back's tiny muscles are controlled by the medial branch nerves, losing these nerves isn’t harmful.
What is Medical Branch Nerve Block?
A diseased or inflamed facet joint in the spine can cause pain, which can be treated with a medial branch block. A bony component that joins the spinal vertebrae together is called a facet joint. Facet joints give the vertebrae more support and stability while also assisting in the control of the spine's mobility. According to clinical studies, facet joint discomfort accounts for about 45% of all neck and back pain that patients report.
Although facet joint issues are frequently the source of neck and back pain, trauma or an accident can also cause chronic pain. Another common problem that can impact the facet joints is arthritis. It appears when the synovial fluid that cushions the joints or the cartilage that covers it starts to degrade. While arthritis frequently develops with aging, it can also be brought on by an autoimmune disorder. Back pain and spinal irritation may be caused by arthritis, especially in the facet joints. Chronic back pain can also be driven by bad posture and scoliosis, which is an abnormal curvature of the spine.
Medial Branch Nerve Block vs Medial Nerve Radiofrequency Ablation
Anesthesia is injected close to tiny medial nerves that are related to a particular facet joint during a treatment known as a medial branch nerve block. In one treatment, the spine is often injected at many levels. The facet joint is identified as the patient's pain source if the patient feels significant pain relief immediately following the injection.
The procedure is mostly diagnostic, but if the patient experiences adequate pain reduction following a medial branch nerve block, he or she may qualify for a later procedure termed medial branch radiofrequency neurotomy (or ablation) that provides longer-lasting pain relief.
When a patient's pain has been identified as coming from a facet joint by a medial branch nerve block, a radiofrequency neurotomy may be an option for longer-term pain treatment. The nerve that sends the pain signal to the brain is burned during a radiofrequency neurotomy, a form of injection procedure. A radiofrequency neurotomy aims to stop the brain from receiving pain signals while maintaining other functions including normal sensation and muscular strength.
Medial Branch Nerve Block Indications
Patients with prolonged (>6 months) axial spine discomfort that is poorly understood and managed might consider medial branch blocks. If diagnostic nerve blocks that target the nerves that feed a particular facet joint give pain relief for the patient, Radiofrequency lesioning of the same nerves can be used to produce long-lasting benefits. The performance of medial branch blocks or a subsequent Radiofrequency neurotomy is contraindicated in cases of systemic infection, local infection at the site of the procedure, significant bleeding diathesis, and pregnancy.
Medial Branch Nerve Block Procedure
Before a medical branch block is advised, steroid injections are frequently used as a type of pain control. The injections entail injecting steroids (such as dexamethasone) and anesthetics (like mepivacaine, bupivacaine, or lidocaine) directly into the area where the targeted facet joints are present. Patients typically have long-lasting pain alleviation from the injections. They are also employed as a diagnostic technique to ascertain the feasibility of a medial branch block. A doctor will typically suggest the block treatment next if two steroid injections result in significant pain alleviation.
Compared to a steroid injection, a medial branch block is significantly more targeted and its effects typically stay longer. During the process, the medial branch nerves (for instance) and other nerves that transmit sensory data to the facet joints are targeted. A needle is put into the area where the problematic nerves are located, and then medications that kill nerve tissue are given to block the nerve signals. As a result, facet joint discomfort is significantly reduced and pain signal transmission is temporarily disrupted. According to medical studies, medial branch blocks are a safe and efficient treatment for neck and back discomfort. The fact that this method is non-invasive and prevents patients from needing surgery adds to its many advantages.
The risks of a medial branch block are typically connected to issues with the positioning of the needle or other technical mistakes. For instance, a tiny percentage of block procedures (around 3%) carried out in the upper back or neck resulted in the medication accidentally being injected into a blood artery rather than the intended nerve. But because the placement of the needle is guided by imaging tools like ultrasound, X-ray, or fluoroscope, these types of issues are typically avoided. The accuracy of the needle placement during the process is about 90% when the imaging technique is used. Infection, nerve injury, and bleeding at the injection site are further potential risks.
Steroids and anesthesia are also supplied to the affected area in addition to the chemical that kills nerve tissue. Weight gain, elevated blood sugar, and arthritis are all potential side effects that could result from using steroids. The immune system may also be weakened or stomach ulcers may develop as a result of the steroids. The anesthetic that is injected may produce unintended interactions with the patient's medications and may also cause the gradual desensitization of healthy nerves. The injected anesthetic may occasionally result in nausea, chest discomfort, and transient neurological issues. Only about 2% of patients who had medial branch blocks experienced this. Before determining whether a patient is a good candidate for a medical branch block or not, doctors perform rigorous medical evaluations due to the potential occurrence of such issues.
After the Procedure
The patient usually rests in the recovery area for 20 to 30 minutes after the treatment. The patient will subsequently be asked to do various actions or activities that ordinarily cause pain. This evaluation is carried out to find out whether the medial branch nerve block has lessened the patient's pain.
Medial Nerve Block Results
Depending on whether or not the medial branch nerves addressed by the injection are the ones delivering pain signals, patients may or may not experience pain alleviation in the first few hours following the injection. The medial branch nerve block will not provide pain relief if the targeted joint or joints are not the source of the discomfort.
Any immediate pain alleviation will be discussed by the patient and doctor. In a pain diary, patients should ideally record how much pain relief they have over the following few hours. A pain diary is useful for explaining the injection results to the treating doctor and for organizing additional tests and/or treatments, as necessary.
Except for reducing pain medication for the first 4 to 6 hours following the injection to ensure reliable diagnostic results, patients are free to continue taking their regular medications after the procedure. Occasionally, individuals may have numbness, weakness, or a strange sensation in their neck or back for a few hours following the injection.
The purpose of the medial branch nerve block is to stop the pain signal that is being sent by the medial branch nerves supplying a particular facet joint. This means that within the first four to six hours following an injection, patients may get full or partial pain relief. At this moment (anesthetic phase), they might not even get any pain relief.
To try and provide longer-lasting pain relief, the patient might be a candidate for radiofrequency neurotomy (also known as radiofrequency ablation), depending on how much pain relief they get in the first 4 to 6 hours following the injection.
A patient is often not a candidate for radiofrequency neurotomy unless they report at least an 80% reduction in their pain within the first 4 to 6 hours following the injection.
Days After the Procedure
Apply an ice pack or a cold compress to the area of the injection site will frequently provide pain relief if the area is irritating in the first two to three days following the injection. Patients can resume their regular activities the day after the operation. It is advised to undertake daily exercise and activities in moderation once the pain has subsided. Patients should anticipate that their initial pain will return after the anesthetic phase because the purpose of a medial branch nerve block is diagnostic rather than curative.
Medial Branch Nerve Block Side Effects
Medial branch blocks could come with risks and problems, just like any invasive medical operation. The danger is generally modest, and problems are uncommon. A medial branch injection has the following potential risks and/or complications:
- Allergic reaction. Potential allergies are rarely to local anesthetics and are typical to the X-ray contrast solution.
- Bleeding. Bleeding is an uncommon consequence that affects those with underlying bleeding issues more frequently.
- Infection. Less than 1% to 2% of all injections result in minor infections. Rarely, between 0.01% and 0.1% of injections result in severe infections.
- Symptoms of discomfort getting worse
- A feeling of discomfort at the injection site
- Nerve or spinal cord damage or paralysis. Although extremely rare, damage can be caused directly by the needle, or indirectly by an infection, hemorrhage that causes compression, or injection into an artery that causes occlusion.
Before receiving the injection, patients who are taking a blood thinner (such as clopidogrel or warfarin) should let their doctor know and discuss whether to stop taking it.
Patients should discuss their unique condition with the treating physician since they may not be able to undergo this treatment if they have an active infection.
Additionally, patients should report to their doctor any drug allergies they may have, particularly those to drugs that may be used during the surgery.
Facet Joint Injections
Sometimes, but not usually, a medial branch block is attempted after the patient has already received one or more facet joint injections. An anti-inflammatory steroid solution is injected right into the joint during a facet joint injection. A medial branch block may be advised if the patient has undergone such an injection and other therapies (such as physiotherapy, manual manipulation, and medications) have not provided long-lasting pain relief while also confirming the facet joint as the likely cause of the patient's pain.
A medial branch block may potentially be taken into consideration in place of a facet joint injection as research on the effectiveness of facet joint injections evolves. If the patient cannot handle the steroid and/or an injection straight into the facet joint for any reason, a medial branch block may also be taken into consideration first.
A medial branch block is a useful technique for controlling pain that stops diseased nerves in facet joints from sending messages to the brain. An anesthetic, steroids, and a chemical that disables nerve tissue are all injected during the block. This combination of drugs numbs the injured area, lowers inflammation, and blocks the transmission of pain signals. When a medial branch block procedure is performed, patients typically get significant pain alleviation that could last up to two years. The block method is also employed as a diagnostic tool to identify the precise location of facet joints that are affected.