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.
Medial Branch Nerve Block 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.
Patients may continue to take their 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 diagnostic information obtained is accurate.
On the day after the procedure, patients may return to their 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 the patient has during the first 6 to 12 hours after the injection, the patient 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.
Frequently Asked Questions
What is a Medial Branch Block?
- A medial branch block is a procedure in which an anesthetic and a steroid are injected near the medial branch nerve. This injection blocks the transmission of pain signals from the facet joint.
- This type of injection may be used for therapeutic and/or diagnostic purposes.
- If you feel lasting relief following the injection, it is considered therapeutic. If you do not feel relief, then this joint is not the source of the pain and this is considered diagnostic. If you feel relief for a short period of time and then it returns, you may be a candidate for another type of procedure that can give more lasting relief.
What should i expect during the injection?
- A local anesthetic will be used to numb your skin. The doctor will insert a thin needle near the medial nerve using fluoroscopy, a type of x-ray, to ensure the safe and proper position of the needle. Once the doctor is sure that the needle is in the correct place, the medicine is injected.
What can I expect after the injection?
- You will be monitored in the post procedure area for about 30 minutes.
- You will be given discharge instructions before leaving. Please use this time to ask any follow up questions that you may still have.
- If you feel relief, you may want to check by moving your back in ways that have hurt in the past, but don’t over do it.
- You may feel immediate pain relief and numbness in your back for up to 6 hours following your procedure. If your pain goes away for a short time but then comes back, this may indicate that you are a good candidate for a Radio Frequency. Your doctor will discuss this option with you at that time.
- You will need someone to give you a ride home after the procedure since it is not safe to drive for the rest of the day following the procedure.
- You should take it easy for the rest of the day, but in most cases you will be able to return to work the next day. As always, you should ask your doctor and follow his advice regarding your post procedure recovery needs.
What are the possible side effects or complications of a medial branch block?
- As with most procedures there is a very small risk of infection, bleeding, nerve injury, or allergic reaction to the medication used.
- It is also possible for some of the anesthetic to spread to the surrounding areas and cause numbness or weakness.