Diagnostic Medial Branch Blocks (MBB)
Medical branch blocks are performed to block pain signals sent from the medical branch nerves, which supply the facet joints. These injections or blocks can be used for diagnosis and to provide long-term pain relief. Long term pain relief can be achieved with radiofrequency neurotomy of the medical branch nerves. However, a positive response with a medical branch block is required prior to performing a radiofrequency neurotomy or ablation.
The Facet Joints, along with the Intervertebral Discs (as in a “herniated disc”) form the motion segments of the spinal/vertebral column; i.e., they allow us to bend forward, backwards, side-to-side, and rotate. Facet joints also bear about ¼ of the axial load of the body weight. These joints are enclosed within a capsule which has the same nerve supply of some of the back muscles. Thus, problems within or associated with this capsule and/or with the facet joint as a whole can cause significant pain and discomfort for patients. There are many clinical reasons underlying Facet Joint dysfunction, but the most common causes are arthritis of the facet joint and abnormal facet joint motion from either Degenerative Disc Disease, or traumatic ligament damage.
A medial branch block is done to block or interrupt the sensory nerve supply to the involved facet joint through the use of a precise administration of an anesthetic agent. A local skin anesthetic is applied, then the physician uses fluoroscopy (x-ray) guidance to place a needle along the nerves of the affected joint.
The benefit from this procedure will typically occur almost immediately following the procedure. The patient is asked to go home and keep a log to record pain levels during the first days after the procedure. This will assist in establishing an accurate diagnosis of the facet joints as the pain source.