A medial branch block is an injection procedure for certain types of back pain. It targets specific spinal nerves to identify and temporarily relieve pain from facet joints. This minimally invasive approach serves as a diagnostic tool and provides short-term pain relief for discomfort related to these spinal structures.
Understanding Medial Branch Nerves
The spine consists of bones called vertebrae, with small facet joints between them. These facet joints allow for various spinal movements, including bending, twisting, and extending. Each facet joint is supplied by small sensory nerves called medial branch nerves, which transmit pain signals from the joints to the brain. When facet joints become inflamed or damaged, such as from arthritis or injury, these medial branch nerves can send pain signals, leading to localized back or neck pain.
Performing a Medial Branch Block
The medial branch block is an outpatient procedure. Before the injection, the patient is positioned, usually lying face down, and the skin over the injection site is cleansed with an antiseptic solution. A local anesthetic is then administered to numb the skin. Using real-time imaging guidance, such as fluoroscopy (a type of X-ray), a healthcare provider guides a thin needle to the precise location near the medial branch nerves. Contrast dye may be injected to confirm accurate needle placement before the anesthetic solution is delivered.
Purpose and Expected Outcomes
A medial branch block serves as a diagnostic tool to pinpoint the source of a patient’s pain. If the injection of anesthetic significantly reduces pain within hours of the procedure, it suggests the targeted facet joints are the source of the discomfort. While the pain relief from the anesthetic is temporary, lasting a few hours to a few days, it provides valuable information for further treatment planning. If an individual experiences at least 80% pain relief for a few hours following the block, it indicates the facet joints are contributing to their pain.
Considerations and Subsequent Steps
After a medial branch block, patients can return home the same day, though they will need someone to drive them. Temporary soreness or mild discomfort at the injection site is common, usually resolving within a few days. Temporary numbness or weakness near the injection site may also occur due to the anesthetic.
If the medial branch block provides significant temporary pain relief, it indicates the facet joints are the pain source, and a more lasting procedure, such as radiofrequency ablation (RFA), may be considered. RFA targets the same nerves with heat to disrupt pain signals for a longer duration, often providing relief for several months to over a year. Conversely, if the block does not provide relief, it helps rule out the facet joints as the primary cause, guiding the healthcare provider to explore other potential pain sources.