Medial Branch Blocks

Pain Caused by the Facet Nerves

Medial Branch Block FAQ

Medial branch nerves are small nerves that feed out from the facet joints in the spine, and therefore carry pain signals from those joints. Facet joint injections are often used to identify a pain source; however, these injections, and other treatments that may be tried, do not always provide lasting pain relief. In such cases, it might be beneficial to confirm that the facet joint is the source of a patient’s pain so that a radiofrequency medial branch neurotomy may be considered for longer term pain relief.

A medial branch nerve block temporarily interrupts the pain signal being carried by the medial branch nerves that supply a specific facet joint. If the patient has the appropriate duration of pain relief after the medial branch nerve block, that individual may be a candidate for a neurotomy. A radiofrequency neurotomy is a type of injection procedure in which a heat lesion is created on certain nerves with the goal of interrupting the pain signals to the brain. A neurotomy should then provide pain relief lasting at least nine to fourteen months and sometimes much longer.

Anatomy of the Cervical, Thoracic, and Lumbosacral Medial Branch Nerves

• Cervical medial branch nerves are located in a bony groove in the neck
• Thoracic medial branch nerves are located over a bone in the mid-back
• Lumbosacral medial branch nerves are found in a groove in the low back

These medial or lateral branch nerves do not control any muscles or sensation in the arms or legs so there is no danger of negatively affecting those areas. The medial branch nerves do control small muscles in the neck and mid or low back, but loss of these nerves has not proved harmful.

Medial Branch Nerve Block Procedure

As with many spinal injections, medial branch blocking procedures are best performed under fluoroscopy (live x-ray) for guidance in properly targeting and placing the needle (and for avoiding nerve injury or other injury).

On the day of the injection, patients are advised to avoid driving and doing any strenuous activities, and to get plenty of rest the night before.

The injection procedure includes the following steps:

• An IV line will be started so that adequate relaxation medicine can be given, as needed.
• The patient lies on an x-ray table, and the skin over the area to be tested is well cleansed.
• The physician treats a small area of skin with a numbing medicine (anesthetic), which may sting for a few seconds.
• The physician uses x-ray guidance (fluoroscopy) to direct a very small needle over the medial branch nerves.
• Several drops of contrast dye are then injected to confirm that the medicine only goes over these medial branch nerves.
• Following this confirmation, a small mixture of numbing medicine (anesthetic) will then be slowly injected onto each targeted nerve.

The injection itself only takes a few minutes, but the entire procedure usually takes between fifteen and thirty minutes.

After the procedure, the patient typically remains resting on the table for twenty to thirty minutes, and then is asked to move the affected area to try to provoke the usual pain. Patients may or may not obtain pain relief in the first few hours after the injection, depending upon whether or not the medial branch nerves that were injected are carrying pain signals from the spinal joints to the brain. On occasion, patients may feel numb or have a slightly weak or odd feeling in their neck or back for a few hours after the injection.

The patient will discuss with the doctor any immediate pain relief. Ideally, patients will also record the levels of pain relief during the next week in a pain diary. A pain diary is helpful to clearly inform the treating physician of the injection results and in planning future tests and/or treatment, as needed.