Medial branch block injections are a diagnostic procedure used to help diagnose the source of neck or back pain. The medial branch nerves of the spine are tiny nerves whose primary function is to allow sensation from the facet joints. There is a right and left facet joint at each level of the spine. These joints can become painful in the same ways that knee, hip, shoulder, or finger joints do. It is often very difficult to determine if a particular joint is painful based only on MRI and physical exam, so medial branch blocks (and sometimes facet joint injections) serve as diagnostic procedures to help identify where the pain is coming from. The procedure “blocks” (with local anesthetic) your ability to feel any sensation coming from whichever joint is targeted. This is not meant to cure the problem. It is only a diagnostic test to identify the source of the pain. You must pay careful attention to how you feel after the injection. A positive response occurs when your pain disappears for the expected length of time (which is different for different anesthetics). Once the painful joint or joints is/are identified, a procedure called radiofrequency ablation (RFA) or radiofrequency neurotomy may be used to achieve long lasting pain relief.
You will feel the pinch of the needle on your back, but a very small needle is used and it is not inserted very deep. You may have some medication to reduce anxiety, which may allow you to nearly sleep through the procedure, but heavier anesthesia cannot be used as it may impede the diagnostic accuracy of the test.
The actual injection usually takes 10 to 20 minutes, but you will need to be at the hospital or surgery center for about 60 to 90 minutes from check-in and check-out.
The medication injected is a local anesthetic (usually lidocaine or bupivicaine).
It’s not a cortisone shot? No. There are no steroids injected. It is a diagnostic test, not a treatment.
Facet injections are combination diagnostic and therapeutic procedures, which may provide pain relief for days, weeks, months, or longer. Medial branch blocks (MBBs) are purely diagnostic procedures done in preparation for a possible radiofrequency ablation. Pain relief will usually only last a few hours. MBBs are generally done when a previous facet injection provided only short-term relief.
Side effects are rare, but may include a temporary increase in pain or vasovagal reaction (fainting).
There are three main complications: bleeding, infection, allergic reaction, or nerve damage. These are all very rare when the appropriate precautions are taken. Injections in the cervical spine (neck) are always inherently riskier than injections in the lower back. When properly performed, the needle does not enter the spinal canal during a medial branch block injection, and therefore risk of complication is much less than in other types of spinal procedures. Fluoroscopy (low power X-ray) is used for safety and to verify appropriate needle placement.
You must stop any blood thinning medication 7 to 10 days before the procedure to prevent bleeding. This includes aspirin (and 81mg “baby aspirin”), coumadin, plavix, advil, motrin, aleve, naprosyn/naproxen, ibuprofen, excedrin, any cold or sinus medication containing these, and other anti-inflammatory medications. If you are not sure if you need to stop a medication, you should ask. Diabetes medication may need to be held the morning of the procedure if you do not eat breakfast. Blood pressure and other heart medications should be continued.
When can I go back to work? No. In fact, you should perform usual activities which cause pain to see if the local anesthetic blocks the pain in the first few hours after the injection. This will help with the diagnosis – to determine if the joints blocked are truly the source of your pain.
Depending on the type of injection, you should avoid submerging your back in water for 2-3 days after the injection. This includes a bath, hot tub, swimming pool, or the ocean. You may shower the night after the injection, unless told not to by the doctor.
You should not travel long distance for one week after the injection.
Dr. Baker has many years of experience performing these injections and has performed over 1,000 injections. She is a member of the International Spine Intervention Society and regularly attends meetings, conferences, and workshops to remain up to date on the latest innovations in spine care.