The facet joints are small joints in the back of the spine, which limit how far back you can bend or twist and which enhance stability of the spine. The facet joints are supplied by small nerves called “medial branches.” The major nerve root leaves the spinal canal and divides into two branches, a large anterior branch, which does important things like tell the muscles how to move, and a small posterior branch. The posterior branch divides into three tiny branches, one of which is called the medial branch. The only thing the medial branch does is to supply the facet joint and a very small muscle, the multifidus, which extends between two vertebral bodies.
Anatomic model of the spine, showing facet joints
Damage to the facet joint is a common cause of back and neck pain. Both areas are highly susceptible to degeneration and injury, such as whiplash. The only way to diagnose whether the facet joints are the source of pain is to numb the joint and see if the pain goes away. Once we know the source of the facet joint pain, we can recommend various treatment options. This process of injecting the facet joints can be done either by injecting into the joint itself or by injecting the nerves, which supply the joint.
Dye injection of the facet joint
In both cases, we use fluoroscopic guidance to place the needle and precisely inject small amounts of local anesthetic so that only the joint or the nerve is being injected. We then ask you to rate your pain relief. Essentially, what we are doing is no different from what a dentist does when he numbs your mouth.
Diagnostic facet injections have a high amount of what are called “false positive” responses. This means that you have pain relief, but the cause of the pain relief is not the local anesthetic around the facet joint but some other unknown cause. We have several responses to this problem. Firstly, we demand excellent pain relief from the diagnostic injection. Secondly, one can do two diagnostic injections with different local anesthetics, each of which lasts for a different length of time. If the pain is coming from the facets, you should be able to correctly tell how long each local anesthetic lasts.
If results from these diagnostic blocks show that your pain is coming from the facet joints, it is possible to get longer term relief by a process called Radiofrequency Thermocoagulation. This process involves putting a needle by the nerve supplying the facet joint, the medial branch, and then heating it. This heating is done by passing a very high frequency current, 500,000 cycles per second, through the needle. A small area of several millimeters around the needle is created where the tissue gets very hot and the nerve is destroyed.
You can safely heat up this nerve because all it does is supply the facet joint one small muscle. Its absence will not harm you.
There is a high incidence of false positive results with the diagnostic procedures. We maintain high standards in terms of when we decide to proceed with a facet neurotomy. Despite this selectivity, it is possible that your pain will return after the procedure.
As we are performing a heat lesion, you may be sore for several weeks after the procedure. This is normal and can be treated with ice on and off for twenty minutes as needed.