Lumbar Medial Branch Blocks


Lumbar medial branch blocks are used as a diagnostic tool to determine if facet joints are causing back pain. During the procedure, a physician injects an anesthetic near the medial nerves. If the patient experiences pain relief upon injection, the facet joint is likely the source of pain and the patient is a candidate for a subsequent procedure, called a radiofrequency neurotomy.

The facets are small, bony joints that connect the vertebrae of the spine. The lumbar facet joints guide motion in the lower back, as well as provide stability to the spine. The nerves supplying the facet joints are called medial branch nerves. When the facet joints become arthritic or injured, patients experience back pain and aches in the legs.

Medial branch blocks work by numbing the medial branch nerve and stopping the transmission of pain signals to the brain. The procedure lasts about 15 minutes and include the following steps:

  • The patient lies face down on a table with a pillow underneath their stomach

  • The target area is cleaned and numbed

  • The physician accurately positions a small needle using X-ray guidance

  • Contrast dye is injected to ensure that medication will flow to the target area

  • A small amount of anesthetic is injected, disrupting pain signals


Lumbar medial branch blocks are used to determine if chronic neck or back pain is originating in the facet joints. The procedure is considered medically necessary if the following criteria are met:

  • Pain worsens during maneuvers such as hyperextension and rotation

  • Conservative treatments such as physical therapy fail to alleviate pain

  • Clinical findings and imaging studies show no other obvious cause of pain

  • The spinal motion segment is not posteriorly fused

A second lumbar medial branch block, performed to validate the response to the initial injection, is considered medically necessary if the following criteria is met:

  • The patient experience at least 80% pain relief after the first injection

  • The second injection is administered at the same level as the first injection

  • A radiofrequency joint ablation procedure is under consideration