FAQ’s on Medial Branch Block
A medial branch is a secondary extension of a nerve fiber that branches off from the main nerve, similar to the limbs of a tree. These secondary branches function to connect the main nerve ending to the surrounding spinal tissue, and are the primary sensory link between the facet joints and the spinal nerve roots.
A facet joint is a small protrusion of bone located on both sides of the spine that provide mobility to the vertebrae, creating the bending motion for the spine. The medial nerve branches are housed in-between the facet joints, providing sensation to them. Patients who are experiencing pain in, or around, the facet joints may be able to obtain symptomatic relief through the use of a medial branch block, which numbs the medial branches to stop the transmission of pain signals to the brain.
What will a Medial Branch Block treat?
Medial branch blocks are an effective treatment for pain caused by complications in either the medial branches or in the facet joints of a patient. The most common cause of symptomatic pain in the facet joints is from arthritic inflammation, but may also be present due to an afflicted nerve root or medial branches. Facet joint arthritis accounts for between 15 and 20% of all cases of chronic lumbar spinal pain.
A medial branch block can also be effective for patients who are experiencing pain due to a direct injury of one or more facet joints and the associated medial branches, such as the result of a compression fracture as seen in this study (Effect of medial branch block in chronic facet joint pain for osteoporotic compression fracture, 2013).
How is a Medial Branch Block performed?
A medial branch block can be performed for as either a diagnostic tool or a therapeutic treatment for patients. When performed as a diagnostic block, the medial branches are temporality blocked to confirm whether or not they are the root source of symptomatic pain for a patient. A diagnostic block is performed by injecting only a small amount of anesthetic into the medial branches to test their reaction. If symptomatic pains are ceased, it can be confirmed that the medial branches are the root source of pain for a patient.
After confirmation of the medial branches as a source of pain, a therapeutic injection using a larger dosage of anesthetic can be performed to provide extended symptomatic relief. To perform either a diagnostic or therapeutic medial branch block, patients will be asked to lie prone to offer the physician access to their spine. The injection site will be thoroughly cleaned, sterilized, and numbed with local anesthetic in preparation for the injection needle. Fluoroscopic imaging will be used for guidance to ensure the needle is accurately placed into the afflicted medial branch.
How well does a Medial Branch Block work?
The therapeutic effects of a medial branch block will be immediately present for patients, and can provide relief that lasts upwards of six weeks. One area of particular effectiveness is the thoracic medial branches, where patients can reliably obtain relief with or without a steroidal supplement according to studies (Comparative effectiveness of a one-year follow-up of thoracic medial branch blocks in management of chronic thoracic pain, 2010).
Patients who obtain a certain percentage of pain relief (typically between 50 and 80 percent) may become eligible for a medial branch radiofrequency ablation. This is the carefully controlled destruction of a chronically problematic nerve ending to provide lasting symptomatic relief, and has been shown to be a very effective method of treating facet based joint pain in patients with medial branch pain in trials (Efficacy of combined treatment with medial branch radiofrequency neurotomy and steroid block in lumbar facet joint arthropathy, 2012)
What are the risks of Medial Branch Blocks?
There is a small risk of infection, bleeding, or soreness at the site of injection. The largest risk faced by patients is simply that the block will not be able to provide a therapeutic effect.