Ep. 40 Pain Procedures: Medial Branch Blocks

Episode Summary:

In this episode of 'It's Not In Your Head,' hosts Justine Feitelson and Dan Bates transition from conservative pain management strategies to discuss advanced interventional techniques aimed at diagnosing and treating lower back pain. Dan dives deep into the technique of medial branch blocks, explaining their significance in pinpointing the specific physical drivers of non-specific lower back pain. The episode offers a detailed look at the diagnostic and procedural process, and the next steps in therapeutic intervention, including radiofrequency ablation. Tune in to understand how to move from a non-specific diagnosis to more targeted treatment that improve patient outcomes.

Episode Overview:

Introduction and Context

• The episode shifts focus from conservative pain management strategies discussed in previous episodes to procedural interventions aiming at specific physical causes of pain, particularly for focal pain rather than widespread sensitization or nervous system dysfunction.​

• Dr. Dan leads the discussion, explaining practical procedures used to identify and treat specific sources of pain, especially when a patient’s diagnosis has been “non-specific”.​

The Problem of Non-Specific Diagnoses

• Many patients receive a non-specific diagnosis for lower back pain due to difficulty in pinpointing the exact cause through history, examination, or imaging.​

• Non-specific treatments match these broad diagnoses, often resulting in inconsistent outcomes, as one would treat different conditions (like sacroiliac joint versus facet or disc pain) the same way.​

Five Major Sources of Lower Back Pain

• The episode lists five primary drivers of back pain:

  • Facet joints: 15–40%

  • Sacroiliac joints: 10–20%

  • Hip joints: 5–10%

  • Discs: 16–20%

  • Nerves (with leg pain): 12–40%

• How to triage: If pain is worse in legs, start with nerves; if worse in back, divide above and below the belt line for facet/disc and sacroiliac/hip concerns.​

Diagnostic Blocks: Medial Branch Block

• The procedure covered is the “medial branch block,” used to help identify pain from facet joints and distinguish them from other pain sources.​

• Medial branch blocks differ from facet joint injections, which are less diagnostically useful because the facet joint only holds a small fluid volume; additional fluid spreads and can block other structures, muddying results.​

• The medial branch is a nerve supplying the facet joint; blocking it can reveal whether the facet is the pain source and predicts responsiveness to radiofrequency ablation, a therapeutic procedure.​

Performing the Medial Branch Block

• The block is performed under x-ray or CT guidance, injecting a small amount of local anesthetic (0.3–0.5 mL) and contrast to confirm placement and avoid blood vessels.​

• After the block, patients use a pain chart to record their pain pre- and post-procedure for about six hours.​

• Key insight: Pain should go away and return the same day. This is normal and expected. The degree of temporary relief predicts the likelihood of longer-term success with radiofrequency ablation: higher relief percentage means higher chance of sustained benefit.​

Stepwise Diagnostic Approach

• Sometimes, two diagnostic blocks are performed (short- and long-acting anesthetic) to increase accuracy (“60-90 rule”).​

• Less than 50% pain relief: May indicate another pain source; in these cases, additional blocks are tried at different levels.​

• 80% or greater pain relief: Proceed directly to therapeutic intervention.​

Patient Experience and Risks

• Patients follow-up with nursing staff post-procedure; if the plan doesn’t go as expected, further review and blocks may be needed.​

• Risks include infection, rash, bruising, and flare-ups, especially in pain-sensitized patients. Increased pain after a block may reflect central sensitization and should prompt a shift in treatment focus.​

• If pain doesn’t improve, that source is ruled out, which progresses the diagnostic journey rather than restarting it.​

Recap and Listener Guidance

• Diagnostic process for facet pain is similar regardless of spinal region (neck, thoracic, lumbar).​

• Refer to previous episodes on managing low back pain and learning to “draw your pain” for more foundational understanding around these concepts.