As with many spinal injections, medial branch blocking [MBB] 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.
- An IV line will be started so that adequate relaxation medicine can be given, as needed.
- You will lie down on an x-ray table, and the skin over the area to be tested is well cleansed.
- Your doctor treats a small area of skin with a numbing medicine (anesthetic), which may sting for a few seconds.
- Your doctor 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 about thirty minutes.
After the Procedure
After the procedure, you typically remain 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 carryig 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.
You 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.
Results and Follow-Up
The medial branch nerve block is designed to interrupt the pain signal being carried by the medial branch nerves that supply a specific facet joint. Because of this, patients may feel complete or partial pain relief during the first 6 to 12 hours after an injection. They may also feel no pain relief during this time (anesthetic phase). If the area is uncomfortable in the first two to three days after the injection, applying ice or a cold pack to the general area of the injection site will typically provide pain relief.
You may continue to take your regular medications after the procedure, with the exception of limiting pain medicine within the first four to six hours after the injection so that the test information obtained is accurate.
On the day after the procedure, you may return to your regular activities. When the pain is improved, it is advisable to start regular exercise and activities in moderation. Even if the pain relief is significant, it is still important to gradually increase activities over one to two weeks to avoid recurrence of pain.
Depending on the amount of pain relief you obtain during the first 6 to 12 hours after the injection, you may be a candidate for a radiofrequency neurotomy procedure – to try and provide longer term pain relief. Generally, a patient must report at least 80% improvement in their pain during the first 6 to 12 hours after the injection to be considered a candidate for radiofrequency neurotomy.