Background: There is uncertainty in the literature over the relative effectiveness of lumbar
epidural interlaminar (IL) steroid injection versus transforaminal (TF) steroid injection for
lumbar radiculopathy. Most studies to date have been retrospective, or technically focused.
Objective: To complete a randomized, blinded, prospective outcome study of the
short-term benefit for IL versus TF epidural steroids for the treatment of subacute lumbar
radicular pain.
Study design: Prospective, randomized, blinded, subacute efficacy trial.
Setting: Tertiary care pain management center, major metropolitan city, United States
Methods: After institutional review board approval, 42 age-matched patients with
similar lower back pain and unilateral radicular symptoms were enrolled and randomized
in a patient and evaluating physician blinded trial to IL or TF epidural steroids from 2007
through 2009. Prior to intervention and 10-16 days after injection, each participant was
evaluated by questionnaire and physical exam by an independent physician. All injections
were performed by the same physician. Thirty-eight participants completed the study, 18
in the IL group and 20 in the TF group. Four participants required a repeat injection, and 2
participants crossed over to the alternative injection type (IL to TF).
Results: Overall, physical exam, diagnostic testing, disability, activity, depression measures,
and opioid pill use were similar between the 2 groups, both pre-injection baseline and postinjection improvement. In primary outcomes, the post-injection follow-up Numeric Rating
Scale (NRS) was more greatly reduced in the TF group. The NRS decreased from 7.0 ± 1.9 to
3.9 ± 3.1 (mean values +/- standard deviation) in the IL group and 6.4 ± 2.1 to 1.7 ± 1.4 in
the TF group. The Oswestry Disability Index was reduced from 37.5 ± 12.6 to 19.0 ± 16.7
in the IL group and 38.3 ± 6.4 to 21.6 ± 16.8 in the TF group. In secondary outcomes, the
depression scale was reduced from 4.39 ± 3.22 to 2.28 ± 3.20 in the IL group and 4.10 ±
1.94 to 1.65 ± 1.63 in the TF group. Walking tolerance was increased from 8.1 ± 4.6 blocks
to 10.6 ± 4.4 in the IL group and 8.9 ± 5.3 blocks to 11.8 ± 4.2 in the TF group.
Limitations: The study did not examine long-term outcomes. A single experienced
interventionalist performed all injections.
Conclusion: Results suggest that patients may experience greater subjective relief, at
least initially, from TF epidural steroid injections over IL. However, more objective, and likely
subacute, therapeutic effects are similar.
Key words: epidural, steroids, interlaminar, transforaminal, lumbar, lumbosacral,
radicular, low back pain
Comparison of therapeutic effects of steroid injection by benign vocal fold lesion type
