Lumbar Medial Branch Block Volume-Dependent Dispersion Patterns as a Predictor for Ablation Success: A Cadaveric...

Area of Science:

• Anatomy
• Pain Management
• Radiology

Background:

• Lumbar facet arthropathy is a frequent cause of low back pain.
• Radiofrequency ablation (RFA) is a common treatment for lumbar facet arthropathy.
• Diagnostic blocks are used to predict RFA success but have high false-positive rates.

Purpose of the Study:

• To investigate how injectate volume affects the spread of lumbar medial branch blocks.
• To determine if smaller volumes (0.25 mL) offer greater specificity than larger volumes (0.5 mL).
• To assess the impact of injectate volume on the accuracy of diagnostic blocks for RFA.

Main Methods:

• A cadaveric study was conducted using six lumbar spines.
• Fluoroscopically guided medial branch injections were performed with 0.25 mL and 0.5 mL volumes.
• Post-injection CT imaging and dissection were used to analyze injectate spread.

Main Results:

• Both 0.25 mL and 0.5 mL volumes adequately covered the medial branches.
• The 0.5 mL volume showed significant spread to adjacent muscles and distal nerve segments.
• The 0.25 mL volume remained localized to the deep and intermediate lumbar muscle layers.

Conclusions:

• A 0.5 mL injectate volume may cause unintended blocks of adjacent nerves, reducing diagnostic accuracy.
• A 0.25 mL injectate volume reliably targets lumbar medial branches with minimal spread.
• Using 0.25 mL for lumbar medial branch blocks may enhance specificity for RFA planning.