Facet joints are small joints up and down the spine that allow motion. They can develop arthritis like other joints and be a cause of pain. Facet blocks have been used to help doctors decide whether or not facet joints are a cause of neck or back pain. However, only
half the time a single set of nerve blocks will be accurate in making the positive diagnosis of facet joint pain. If the first nerve block reduces pain by a significant amount such as 80 percent, it should be repeated. If the second one relieves pain also, then the facet joint(s) is considered positive as a source of neck or back pain.