Medial branch nerves are the tiny nerve branches that communicate pain caused by the facet joints in the spine. Blocking these medial branch nerves with an anesthetic temporarily stops the transmission of pain signals from the joints to the brain, providing valuable insight into the source of your pain and helping your doctor develop a plan for long-term relief.
The facet joints are small joints on either side of the spine that connect the vertebrae together and allow for movement. The medial branch nerves branch off from the spinal nerves and supply sensation to the facet joints in your spine. They do not control any muscles or sensations in your legs or arms.
When the facet joints are irritated or inflamed due to conditions like arthritis or injury, the medial branch nerves transmit pain signals to the brain. This pain is typically felt on the side of the spine and can be dull or achy.
Understanding how medial branch nerves work is crucial for diagnosing the source of back pain. Medial branch blocks can help pinpoint if the facet joints are the culprit. If the block relieves your pain, it suggests that the facet joints are causing your spine pain.
Medial branch blocks contain an anesthetic medication delivered around the medial branch nerves. The anesthetic numbs the nerves, which can help to relieve pain coming from the facet joints.
Medial branch blocks offer several benefits, particularly for those experiencing chronic back pain:
Immediately after the procedure, you will go to a recovery area and be asked to rate your pain on a scale. You may be asked to move around and try to imitate something that usually brings about your typical pain. You may receive a pain log to rate your pain relief for the next several hours after the procedure. The physician will use this information to plan for your further care. Of note, depending on the area treated, the arm(s) or legs(s) may feel weak or numb for up to a few hours after the procedure.
You may return to your normal activities on the day of your procedure, including returning to work.
Medial branch blocks are performed to determine whether or not the facet joints are causing back or neck pain. If a medial branch block provides good (at least 80%) pain relief for the duration of the numbing medicine, you may be a candidate for a radiofrequency ablation. If a medial branch block provides no (or minimal) pain relief, then the facet joints are likely not the cause of pain, and radiofrequency ablation is not indicated.
Medial branch blocks are done at two different times to ensure the facet joints are the true pain generators. The first time the procedure is done, a short-acting numbing medicine (Lidocaine) is used, and the pain is expected to be relieved for 1-2 hours. The second time the procedure is done, a longer-acting numbing medicine (Marcaine) is used, and the pain is expected to be relieved for at least three hours, typically four to six hours. It is important to note that medial branch blocks are test procedures only, so pain relief is temporary.
The next indicated procedure is a radiofrequency ablation (see our separate handout on this).
If a medial branch block provides no pain relief, the facet joints are not the true pain generators. At this point, you would need to be reevaluated by the physician to determine the cause of your pain.
Everyone will feel a “pinch and burn” when the local numbing medicine is injected. Beyond that, feeling pressure as the needle travels to the target is normal. Usually, patients only feel mild discomfort during these procedures.
Unfortunately, sedation is not recommended for this procedure. Because this is a test procedure, sedation makes it difficult to determine whether pain relief (if present) is due to the numbing medicine or the sedation.
Risks include but are not limited to bleeding, infection, and reaction to the medications used. Serious reactions are exceptionally rare.
Medial branch blocks are highly specialized procedures that require a fluoroscopy (X-ray) machine, a physician trained to do these procedures, an X-ray technician, and a nurse. In many cases, they require insurance authorization as well. Before a medial branch block, you also cannot eat anything for six hours or drink anything for two hours. For these reasons, medial branch blocks are scheduled on certain days. Before any procedure, a clinic visit is typically done to review imaging, discuss the procedure in depth, review risks and benefits, and give the patient a chance to ask any questions. This helps the procedure run smoothly.
Because of the position you will be in (prone or on the stomach), there is a small risk of aspiration. This occurs when the stomach contents go up the esophagus and back down the windpipe.
Blood thinners are held prior to any cervical medial branch blocks because if there is significant bleeding near the spinal cord, this can cause paralysis. Therefore, clearance from the patient’s cardiologist must be obtained to hold the blood thinners for a certain number of days (depending on which blood thinner it is) before the procedure.
Pain relief (if present) is usually immediate but can take several minutes.
Medial branch blocks use numbing medicine, which can temporarily cause the leg or arm to feel numb. This makes it dangerous to drive after the procedure. We recommend asking a friend or family member to drive you. We do not allow taxis or Uber/Lyft, as a driver will not be able to help you get into your home if needed. If you arrive without a driver, you may be asked to reschedule.
You will be in our office for 1 hour. This includes checking in, reviewing risks, and signing a consent form, performing the medial branch block, and recovering. The actual medial branch block takes less than 15 minutes in most cases.
Yes. Medial branch blocks must be done twice to be absolutely certain that the facet joints are the true pain generators. This is also required by insurance in order to obtain authorization for radiofrequency ablation.
You may resume your normal activity as long as your legs or arms do not feel numb. This is encouraged to ensure that the pain relief lasts the appropriate length of time. You should keep a pain diary for several hours to determine if the procedure worked and for how long. Avoid driving for at least six hours after the medial branch block if there is any leg numbness. Avoid soaking or submerging the injection area for 48 hours – this includes baths, hot tubs, or pools. Regular showers are OK. The band-aid placed at the injection site may be removed the same day of the procedure.
Call our office immediately if you experience a severe headache, severe pain in the arm or leg, redness or drainage at the injection site, fevers, chills, or weakness that is worse after you leave the clinic. These symptoms are very rare. If you feel you require immediate medical care, call 911.
Medial branch blocks involve a thorough check-in procedure, which includes verifying the exact procedure and reviewing the risks and benefits of the injection. Therefore, to help ensure our procedures run as smoothly as possible, we ask patients to arrive 30 minutes prior to their scheduled medial branch block. If you arrive late, you may be asked to reschedule. Please let us know at least 24 hours in advance if you need to reschedule or cancel your procedure. A “no-show” may result in a $100 fee.
Cervical/Thoracic/Lumbar Medial BB – PDF
Cervical MBB – PDF
Lumbar/Thoracic MBB – PDF