What is a Medial Branch Block?
Pain management explained by Denver, Golden, Aurora, Boulder, Broomfield, Jefferson, and Littleton Colorado’s top pain doctors
A medial branch block is a direct, non-invasive method of treating pain that originates in the facet joints of the spine. Facet joints, also known as the zygapophysial joints, are located between the vertebrae of the lower back, as well as between the vertebrae of the neck. These joints allow for twisting and bending movement and provide a degree of stability for the trunk. Two nerves, called the medial branch, connect to each facet joint.
Various painful conditions can affect the facet joints as a result of injury, age, poor posture, or genetic spinal abnormalities. Degeneration of the facet joints can cause significant neck or back pain. A medial branch block is the injection of a long-lasting steroid, such as dexamethasome, directly into the medial nerves of the affected facet joint. The steroid works to reduce inflammation around the facet joint, which can reduce pain. In addition to a steroid, an anesthetic like lidocaine is often injected to block pain signals along the nerves.
How is a Medial Branch Block Performed?
During the procedure for a medial branch block, the patient lays down on an X-ray table. If the patient is sedated, the vital signs (blood pressure, heart rate, and breathing) are closely monitored. The skin at the site of the injection is cleaned, sterilized, and numbed with a local anesthetic.
The physician utilizes an injected dye and a real-time X-ray, called a fluoroscope, to guide the placement of the needle. The steroid and anesthetic are injected directly into the medial nerve, and the patient is monitored for about 30 minutes before being discharged. Most patients experience some relief of pain within a couple days of the procedure, while some patients experience immediate pain relief.
Although a medial branch block is a non-invasive procedure, it does carry some risks. Most of these risks are related to technical errors, such as misplacement of the needle. Approximately 3% of medial branch block injections are inadvertently injected into a blood vessel instead of a nerve, but the diligent use of injected dyes, fluoroscopy, or ultrasound during the procedure can help the physician avoid this. Infection, minor bleeding, or nerve damage are also possible. To reduce the chance of bleeding, patients are advised to discontinue other medications before the procedure.
Additionally, there are some potential side effects of the medications used during a medial branch block. Injected steroids can cause elevated blood sugar, weight gain, stomach ulceration, or immune response reduction. Local anesthetics also carry a risk of desensitization of the nerve if used over a long period of time. There is also a chance of an interaction between the anesthetics and other medications the patient is taking. Because of this, it is very important for the patient to inform his or her physician of all medications or supplements he or she takes. In less than 2% of patients, the anesthetic used in a medial branch block can also cause temporary neurological complications like chest discomfort or nausea.
Conditions Related to Medial Branch Blocks
The painful symptoms of several conditions can be relieved by a medial branch block. Facet joints are thumbnail-sized joints connecting the vertebrae of the spine. Each joint is separated by cartilage and cushioned by a fluid-filled capsule. Spinal osteoarthritis can cause the cartilage between the joints to deteriorate, which can lead to facet syndrome. In facet syndrome, the bones of the facet joint rub against each other. Bone spurs can also develop with facet syndrome, and the bone spurs can rub against other bones or against the nerves in the facet area.
Both facet syndrome and bone spurs in the facet area can cause pain, stiffness, inflammation, and tenderness. The steroid in a medial branch block reduces inflammation, while the anesthetic works directly on the medial nerve to block pain signals.
Another condition related to the facet joint is degenerative disc disease, in which the intervertebral discs of the spine degenerate and are unable to act as shock absorbers for the vertebrae. When this happens, the facet joints must realign to compensate for the altered intervertebral disc size. The inflammation and pain that characterizes this disease can be lessened significantly by a medial branch block injection.
In addition to the relief of pain, a medial branch block can act as a diagnostic tool. Because of the many potential sources for back and neck pain, the cause of this pain can often be difficult to diagnose. X-rays, magnetic resonance imaging (MRI) studies, and computed tomography (CT or CAT) scans are used to diagnose the source of back and neck pain, along with patient history and a physical examination. Even with these tools, a diagnosis can still be difficult.
If a patient undergoes a medial branch block and experiences relief from pain, his or her physician then knows that the pain originated from the facet joint. This knowledge can aid in the patient’s future activity, therapy, and medication plans. The relief of pain can also make more invasive therapy methods, such as surgery, unnecessary.
Medial branch blocks are a low-risk, non-invasive method of treating facet joint pain. They are also an effective diagnostic tool. When combined with physical therapy and other physician-recommended medications, such as non-steroidal anti-inflammatory medications (NSAIDs), patients can be significantly assisted with daily functioning. In fact, a recent investigation indicated that 74% of medial branch blocks successfully alleviate pain. These injections provide a realistic alternative to invasive surgeries.
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