Medial branch nerves are small nerves of the spine that carry pain signals from the facet joints (joints of the spine) to the brain. The medial branch block is often used as part of a 2-step diagnostic and treatment approach. Typically several levels of the spine are injected in one procedure. If pain relief occurs with the injection, then the facet joint is determined to be the source of the patient’s pain. The procedure is primarily diagnostic, meaning that if the patient has the appropriate duration of pain relief, after the medial branch nerve block; then they may be a candidate for a subsequent procedure – called a radiofrequency ablation (neurotomy) – for longer term pain relief.