776 - How I Do It: A Primer on Intercostal Blockade for Thoracic Interventions

Learning Objectives: Review indications & procedural techniques for intercostal nerve block, dorsal root ganglion block & ablation

Background: Intercostal nerve (ICN) and dorsal root ganglion (DRG) block & ablation can palliate intractable chest wall pain. The DRG is located at the neuroforamen adjacent to each ICN. Each ICN courses underneath the corresponding rib, and carries chest wall sensory and motor fibers. In this pictorial primer, we provide an overview of our pre-procedural workup, procedural details, and post-procedural management considerations for DRG and ICN blockade.

Clinical Findings/Procedure Details: Our theranostic nerve block solution (NBS) includes a 30 mL bottle of 0.25-0.5% Bupivicaine combined with a 5 mL bottle of 40 mg/mL triamcinolone (200 mg total) and 2 mL of iodinated contrast. For the DRG block, a 25 gauge needle is advanced at an oblique angle lateral to midline just adjacent to the neuroforamina at the origin of the ICN. After confirming position with a small volume injection, 5 mL of NBS is injected. For the ICN block, the 25 gauge needle is positioned in the intercostal space just underneath each relevant rib, and 2-5 mL of NBS is injected. A week delay prior to nerve ablation allows confirmation of the pain etiology, however permanent nerve ablation procedure can be combined with the block. For permanent nerve destruction at the DRG, a single cryoablation probe (IcePearl, Boston Scientific) is guided alongside the DRG, and a dual freeze-active thaw cycle using two cycles of 5 minute freeze & 5 minute active thaw is used. Care must be taken by monitoring the ice ball to avoid extesion into the spinal cord. If truncal nerve cryoablation (CPT 0442T) is not available, then ethanol neurolysis (CPT 64680) can be used. For ethanol neurolysis, 2 mL is injected directly into the DRG. For temporary demyelination using cryoablation of the ICN, the cryoablation needle (IceRod or IcePearl, Boston Scientific) is positioned alongside and parallel to the relevant ICN and dual freeze-thaw of 2 minute freeze and 5 minute thaw is performed. Targeting the ICN instead of the DRG allows for temporary ablation of nerve function, with remyelination and return of intercostal nerve function, which can take up to 9 months.

Conclusion and/or Teaching Points: Targeting the DRG and ICN provides effective pain relief for chest wall pain. Truncal nerve cryoablation of the DRG provides the most precise targeting and durable responses for permanent ablation. Targeting the ICN instead of the DRG allows for remyelination and restoration of function.