Comparison of Clinical Efficacy Between
Transforaminal and Interlaminar Epidural
Injections in Lumbosacral Disc Herniation: A
Systematic Review and Meta-Analysis
Authors: Lee Jung Hwan 
Published: October 2019

Background: Epidural injection (EI) is used to treat back or radicular pain from lumbosacral disc
herniation (LDH). Although several reports have stated that the transforaminal approach in EI (TFEI)
has an advantage in target specificity and yields better clinical efficacy than the interlaminar approach
in EI (ILEI), other studies have indicated that the clinical efficacy of ILEI was not inferior to that of TFEI
and that ILEI also has the ability to spread medication into the ventral space to a degree similar to that
of TFEI. There has been controversy about whether TFEI is superior to ILEI in clinical efficacy.
Objectives: This systematic review and meta-analysis aimed to investigate whether TFEI is more
useful than ILEI for achieving clinical outcomes in patients with LDH.
Study design: A systematic review and meta-analysis using a random effects model on
randomized controlled studies (RCT).
Methods: A literature search was performed in MEDLINE, EMBASE, Cochrane review, and
KoreaMed for studies published from January 1996 until July 2017. From those found fulfilling
the search criteria, manuscripts that compared the clinical efficacy of steroids and control agents,
such as local anesthetics or saline, in terms of pain control and functional improvement were
included in this study. Exclusion criteria included a previous history of lumbosacral surgery, nonspecific low back pain, severe spinal stenosis, and severe disc degeneration. After reviewing titles,
abstracts, and the full text of 6,711 studies; 12 studies were included in the qualitative synthesis.
Data including pain scores, functional scores, and follow-up period were extracted from 10 studies
and analyzed using a random effects model to obtain effect size and its statistical significance. The
quality and level of evidence were analyzed in accordance with the Grading of Recommendations
Assessment, Development and Evaluation (GRADE) methodology.
Results: In terms of pain control, TFEI showed significantly better short-term (2 weeks to 1 month)
outcomes and slightly favorable long-term (4 - 6 month) outcomes, but without significance, in
comparison with ILEI. In terms of functional improvement, TFEI also showed favorable short- and
long-term outcomes, but without significance, in comparison with ILEI. TFEI had target specificity,
required no additional cost and resources, and had equal applicability to ILEI. However, TFEI was
more associated with a higher frequency of discomfort or adverse events during the procedure.
Overall, better results were reported with TFEI over ILEI, but with low-grade evidence due to the
inconsistency and imprecision of the selected studies.
Limitation: Analyses of safety or adverse effects could not be performed due to a lack of
available data from the included studies.
Conclusions: Based on low-grade evidence, TFEI showed significantly better short-term pain
control and slightly favorable outcomes in long-term pain reduction and short- and long-term
functional improvement in comparison with ILEI.
Key words: Epidural injection, interlaminar, transforaminal, meta-analysis, systemic review, pain,
function