Is a left intercostal nerve block medically necessary for a patient with a history of left radicular pain radiating from the inferior pole of the scapula to the axilla, diagnosed with intercostal neuralgia, who has tried physical therapy and medications such as Cymbalta (duloxetine), gabapentin, and Lyrica (pregabalin) without sustained improvement?

Medical Necessity of Left Intercostal Nerve Block for Intercostal Neuralgia

Yes, left intercostal nerve blocks are medically necessary for this patient with chronic intercostal neuralgia who has failed conservative management including 12 sessions of physical therapy and multiple medication trials. 1, 2

Rationale Based on Guidelines

Intercostal nerve blocks are specifically recommended for chronic intercostal neuritis as part of comprehensive pain management when conservative treatments have failed. 1 The American Society of Anesthesiologists guidelines explicitly support nerve blocks for patients with chronic pain who have not responded to other therapies, emphasizing that multimodal interventions should be part of the treatment strategy. 1

This Patient Meets Established Criteria

• Confirmed diagnosis of intercostal neuralgia (G58.8) with characteristic radicular pain distribution from the inferior scapula to axilla 2
• Failed adequate conservative management: 6 weeks (12 sessions) of physical therapy without sustained improvement 2
• Failed multiple pharmacological trials: Cymbalta (duloxetine), gabapentin at higher doses, and Lyrica (pregabalin) at low doses—all first-line neuropathic pain medications per IASP consensus 1
• Chronic pain requiring escalation: The patient has exhausted standard first-line and second-line treatments 1, 2

Evidence Supporting Intercostal Nerve Blocks

Intercostal nerve blocks significantly reduce pain scores and opioid requirements in patients with intercostal neuralgia. 3 Recent high-quality evidence from 2025 demonstrates that intercostal nerve blocks reduce morphine consumption by approximately 40% and lower pain scores in the first 24 hours post-procedure. 3

Specific Benefits Documented

• Pain reduction: Visual analogue scale (VAS) scores decrease significantly following intercostal nerve blocks 4
• Functional improvement: Quality of sleep improves, which is a critical quality-of-life measure 4
• Opioid-sparing effect: Reduces need for systemic opioids and their associated side effects 3
• Superior to oral medications alone: Combined nerve block with pregabalin shows better outcomes than either treatment alone 4

Clinical Algorithm for This Patient

Step 1: Confirm Appropriateness

✓ Chronic intercostal neuralgia diagnosis confirmed
✓ Failed NSAIDs/acetaminophen (implied by progression to neuropathic agents)
✓ Failed first-line neuropathic agents (gabapentin, pregabalin, duloxetine)
✓ Failed physical therapy (12 sessions)
✓ Pain significantly impacting quality of life

Conclusion: Patient meets all criteria for interventional management 1, 2

Step 2: Procedure Selection

Single-shot intercostal nerve blocks (CPT 64420,64421) are appropriate as the initial interventional approach. 2 These should be performed with image guidance (ultrasound or fluoroscopy) to improve accuracy and reduce complications such as pneumothorax. 1, 5

• Ultrasound guidance is preferred as it allows direct visualization of nerves, vessels, muscles, and the pleura, potentially improving accuracy and decreasing complications compared to landmark-based techniques 5
• Local anesthetic choice: Ropivacaine 0.5% or bupivacaine 0.25-0.5% are standard 3
• Consider adjuvants: Adding dexamethasone to local anesthetic prolongs analgesia duration and reduces opioid requirements 2

Step 3: Expected Outcomes and Follow-up

• Initial response assessment: Pain relief should be evaluated within 2-24 hours 3
• Duration of relief: Single-shot blocks typically provide days to weeks of relief 2
• If inadequate response: Consider repeat blocks, continuous catheter techniques, or peripheral nerve stimulation for refractory cases 6

Important Clinical Considerations

Safety Profile

Intercostal nerve blocks have an acceptable safety profile when performed with image guidance. 5 The most significant risk is pneumothorax, which occurs in less than 1% of cases with ultrasound guidance. 5

• Pre-procedure equipment check is essential: Ensure integrity of needles and equipment to prevent unintended nerve injury 7
• Monitor for systemic local anesthetic toxicity: Though rare, plasma levels can be elevated with multiple-level blocks 3

Common Pitfalls to Avoid

• Inadequate conservative trial: This patient has completed appropriate conservative management—do not delay intervention further 1, 2
• Performing blocks without image guidance: Landmark-based techniques have higher failure rates and complication risks 5
• Single medication failure interpreted as "failed medical management": This patient has failed multiple appropriate medication classes, meeting the threshold for intervention 1, 2
• Expecting permanent relief from single-shot blocks: Set realistic expectations that repeat procedures or alternative techniques may be needed 2, 6

Integration with Ongoing Management

Intercostal nerve blocks should be part of a multimodal pain management strategy, not a standalone treatment. 1 Continue appropriate pharmacological management alongside the nerve blocks, and consider:

• Retrial of neuropathic agents at different doses if side effects were dose-related 1, 2
• Physical therapy continuation focusing on thoracic stabilization and posture 1
• If blocks provide temporary but significant relief: Consider radiofrequency ablation for longer-lasting results 5
• If blocks fail: Peripheral nerve stimulation has shown sustained benefit at 2-year follow-up for refractory intercostal neuralgia 6

The requested intercostal nerve blocks (CPT 64420,64421) are medically necessary and represent the appropriate next step in this patient's pain management algorithm. 1, 2