Selective Facet Medial Branch Block
A selective facet medial branch block is sometimes described as a medial block, facet nerve block or facet injection.
Facet blocks are pain-relieving injections used in people who have arthritis or other problems affecting the facet joints, which sit between the bones of the spinal column. These problems are known collectively as facet joint syndrome. In addition to using facet joint injections to relieve pain, doctors use them to distinguish facet joint syndrome from other potential causes of spinal pain.
Facet Joint Basics
Facet joints, technically known as zygapophysial joints, are connecting points located on each side of the rear sections of your spinal bones (vertebrae). Like other joints in your body, they contain cartilage that coats the bone surfaces and prevents bone-on-bone contact, and are enclosed by a supporting tissue structure called a joint capsule, which secretes a protective and lubricating substance called synovial fluid. Facet joints support normal movement in your back by allowing you to twist and bend your spine. They also help prevent your back from moving beyond its functional limits. When nerves branch from your spinal cord to the rest of your body, they must first pass through the facet joints.
Facet Joint Syndrome
Facet joint syndrome occurs when the facet joints become damaged or inflamed, or when enlargement of a facet joint inhibits the normal passage of a spinal nerve. Potential causes of these problems include direct physical trauma and the degeneration associated with arthritis. If you develop facet joint syndrome in your neck, symptoms of the condition can include limited neck mobility and headaches. If you develop the syndrome in your back, you can experience pain in your thighs, buttocks or lower back.
A facet block is typically injected directly inside the enclosed space of your facet joint and does not have an impact on other spinal areas. Usually, you will receive an injection while awake and lying face-down on a table called a fluoroscope, which produces continuous, real-time X-ray images. Before starting the actual procedure, your doctor will locate the joint in question by injecting the appropriate area of your spine with a substance called a contrast dye, which makes your joints easily visible on a fluoroscope monitor. When used for treatment, a facet joint injection contains a combination of an anesthetic and an anti-inflammatory medication called a steroid or corticosteroid. When used for facet joint syndrome diagnosis, the injection contains only a small dose of anesthetic.
Facet Block Benefits for Diagnosis and Treatment
The symptoms associated with facet joint syndrome sometimes mimic the symptoms associated with other spinal problems such as herniated discs or arthritis in other portions of the vertebrae. In some cases, doctors can easily distinguish facet joint problems from these other ailments. However, in other cases, they have problems making these distinctions. Since a facet joint injection doesn’t typically affect other areas in your spine, your doctor can make a definitive diagnosis by injecting a small amount of anesthetic into the facet joint and observing the results. If this injection eases your symptoms, you have facet joint syndrome. You can then gain longer-term relief with an injection that combines a larger dose of anesthetic with a corticosteroid.
Facet Block Risks
Potential side effects from insertion of the needle during a facet block include bleeding, pain at the point of injection and increased intensity of your initial symptoms. Potential side effects of steroid or corticosteroid use include weight gain, sleeplessness, emotional instability, increases in your blood pressure and abnormal retention of body fluids. Most people only develop short-term forms of these problems.
Certain groups of people should avoid receiving facet blocks. They include people taking anticoagulant medications, people who bleed more easily or profusely than normal, and people who have back pain related to cancer or any type of infection. Individuals with lower back pain should also avoid facet joint injections unless more conservative treatment choices have failed and pain has been ongoing for at least one to two months. Some people who undergo a fluoroscope procedure develop radiation burns in their exposed skin or deeper tissues. Radiation exposure from the procedure can also potentially contribute to radiation-related cancer risks over the course of your lifetime.
North American Spine Society: Lumbar Zygapophysial (Facet) Joint Injections (Pages 2-9) http://www.spine.org/Documents/facet_joint_2006.pdf
Cedars-Sinai: Facet Joint Syndrome http://www.cedars-sinai.edu/Patients/Health-Conditions/Facet-Joint-Syndrome.aspx
“Biomedical Imaging and Intervention Journal”: Image-Guided Facet Joint Injection http://www.biij.org/2011/1/e4/e4.pdf
American Academy of Orthopaedic Surgeons: Cervical Spondylosis (Arthritis of the Spine) http://orthoinfo.aaos.org/topic.cfm?topic=A00369
U.S. Food and Drug Administration: Radiation-Emitting Products – Fluoroscopy http://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/medicalimaging/medicalx-rays/ucm115354.htm