Facet Nerve (Medial Branch) Block
What is a facet nerve block?
The facet joints are a series of joints that span the entire length of the spine. They allow the spine to flex, bend, and twist. These joints can become arthritic just like the joints of the fingers, knees, hips and shoulders. A facet nerve block is the injection of a local anesthetic to block the nerves that transmits pain from these facet joints.
What is the purpose of a facet nerve block?
A facet nerve block is a diagnostic procedure to determine if the facet joints are a source of pain. If a facet nerve block works, it will give you relief for several hours, but only on the side that was blocked. After that, the pain is expected to return to normal. This test is always performed twice (usually a week or two apart) because two successful tests are required to move onto treatment. If both diagnostic tests are positive, then we schedule a treatment called radiofrequency (RF) ablation. In this procedure, the same nerves are cauterized, which typically leads to pain relief for up to 12-18 months (please see the link for Facet Radiofrequency Ablation to learn more about this procedure). If this process works well for one side, it can be performed on the other side as well.
How is the procedure performed?
You will be placed on the procedure table. The injection site is sterilized with either iodine or chlorhexadine. The site to be injected is numbed with a local anesthetic, and a needle is directed to the target area. X-ray guidance is used to ensure proper placement and positioning of the needle. When the needle is properly positioned near the facet nerve, local anesthetic is injected to numb that nerve. This will be repeated at multiple levels depending on how many joints are involved.
Will the procedure be painful?
The injection can be uncomfortable but this is reduced as much as possible with local anesthetic, As this is a diagnostic test, it is important to reduce any other medications or changes that could affect the reliability of the test.
What are the discharge instructions?
Rest and relax for the next few hours following the the procedure. You may resume your normal diet immediately. Do not engage in any strenuous activity for 24 hours. You should, however, engage in moderate activity that typically causes your usual pain. If the block works, those activities should not be painful for several hours after the injection. Do not take a bath, swim or use a hot tub for 24 hours (you may shower).
Call the office if you have any of the following: severe pain afterwards (different than your usual symptoms), redness/swelling/discharge at the injection site(s), or fevers/chills, difficulty with bowel or bladder functions.
What are the risks and side effects?
The complication rate for this procedure is very low. Whenever a needle enters the skin, bleeding or infection can occur. Some other serious but extremely rare risks include paralysis and death.
You may have an allergic reaction to any of the medications used. If you have a known allergy to any medications, especially x-ray contrast dye or local anesthetics, notify our staff before the procedure takes place.
You may experience any of the following side effects up to 4 hours after the procedure:
● Dizziness may occur due to a decrease in your blood pressure. If this occurs, remain in a seated or lying position. Gradually sit up, and then stand after at least 10 minutes of sitting.
● Mild headaches may occur. Drink fluids and take pain medications if needed. If the headaches persist or become severe, call the office.
● Mild discomfort at the injection site can occur. This typically lasts for a few hours but can persist for a couple days. If this occurs, take anti-inflammatories or pain medications, apply ice to the area the day of the procedure. If it persists, apply moist heat in the day(s) following.
The side effects listed above can be normal. They are not dangerous and will resolve on their own. If, however, you experience any of the following, a complication may have occurred and you should either contact your doctor. If he is not readily available, then you should proceed to the closest urgent care center for evaluation:
● Severe or progressive pain at the injection site(s)
● Arm or leg weakness that progressively worsens or persists for longer than 8 hours
● Severe or progressive redness, swelling, or discharge from the injections site(s)
● Fevers, chills, nausea, or vomiting
● Bowel or bladder dysfunction (i.e. inability to urinate or pass stool or difficulty controlling either)
How long does it take for the procedure to work?
You should feel relief from your usual pain within the first hour. Again, this is only expected to last for several hours, at the most. Remember, you may be sore in the middle part of your back from the needles, and you must distinguish this from your usual pain.