Medial branch nerves are small nerves that feed out from the facet joints in the spine and carry pain signals from the facet joints to the brain. A medial branch nerve block is a procedure in which an anesthetic is injected near small medial nerves connected to a specific facet joint. Typically several levels of the spine are injected in one procedure. If the patient experiences marked pain relief immediately after 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 the patient may be a candidate for a subsequent procedure – called a medial branch radiofrequency ablation – for longer term pain relief.