For unilateral radicular pain from disc herniation or foraminal stenosis, neither approach should be performed — both right interlaminar and right transforaminal epidural steroid injections are strongly recommended against based on the most recent high-quality evidence.
Strong Recommendation Against Both Approaches
The 2025 BMJ clinical practice guideline provides strong recommendations AGAINST epidural injections of local anesthetic, steroids, or their combination for chronic radicular spine pain 1. This applies to all epidural approaches including both interlaminar and transforaminal routes.
Key Evidence Supporting This Recommendation
- Moderate certainty evidence demonstrates that epidural injection of local anesthetic with steroids for chronic radicular spine pain probably has little to no effect on pain relief compared to sham procedures 1
- No high certainty evidence exists showing important pain relief for any interventional procedure for chronic radicular spine pain 1
- The guideline panel determined that patients would be disinclined to receive treatments with very low to low certainty evidence for benefit when moderate to high certainty evidence of harm exists 1
Serious Safety Concerns
Between 1997 and 2014, the FDA Adverse Event Reporting System captured 90 serious adverse events occurring within minutes to 48 hours after epidural corticosteroid injections, including death, spinal cord infarction, paraplegia, quadriplegia, cortical blindness, stroke, seizures, and brain edema 1. While rare, these catastrophic complications carry unacceptable risk given the lack of proven benefit.
If You Must Choose Between the Two (Against Guideline Recommendations)
Should you proceed despite guideline recommendations, the historical comparative data suggests:
Transforaminal May Have Marginal Short-Term Advantages
- At 2 weeks only: Transforaminal showed 15% better pain relief than interlaminar, though this difference is not clinically significant 2
- At 1 month and beyond: No efficacy difference exists between approaches 2
- One older study (2006) found transforaminal resulted in better short-term pain improvement (70% vs 45% achieving ≥2-point improvement) and lower surgical rates (10% vs 25%) 3
Interlaminar Showed Slightly Better Function
- Interlaminar demonstrated non-clinically significant superiority in functional improvement (56.4% vs 49.4% at 2 weeks) 2
- Combined data across studies showed minimal differences (ILESI 44.8% vs TFESI 40.1% functional improvement) 2
Clinical Context Matters for Route Selection
For single-level pathology: Transforaminal allows targeted delivery to the specific nerve root and may be preferred if proceeding 4
For multilevel stenosis: Interlaminar or caudal approaches are more appropriate as they address multiple levels 5, 4
For severe stenosis: Both approaches show significantly weaker effects; patients with severe stenosis are less likely to benefit 4
Steroid Selection (If Proceeding)
If performing the procedure despite recommendations, betamethasone provides the greatest and most prolonged relief, while dexamethasone shows the lowest benefit 4. Triamcinolone and methylprednisolone offer similar initial relief but decrease more rapidly 4.
Critical Caveats
Guideline contradictions exist: The 2021 ASIPP guidelines provided strong recommendations in favor of fluoroscopically guided transforaminal and interlaminar epidural injections for disc herniation 1. However, the 2025 BMJ guideline represents the most recent, methodologically rigorous evidence synthesis and should take precedence.
These recommendations apply only to chronic pain (≥3 months duration) and do not address acute radicular pain management 1.
The evidence base remains uncertain — only approximately half of randomized trials reported adverse events, and this evidence is low to very low certainty 1.
Given the strong recommendation against both approaches, alternative evidence-based treatments for radicular pain should be prioritized, including physical therapy, oral medications, and consideration for surgical consultation if conservative management fails and significant functional impairment persists.