Pain Physician 2014; 17:277-290• ISSN 1533-3159

Randomized Trial

Transforaminal Versus Parasagittal Interlaminar
Epidural Steroid Injection in Low Back Pain with
Radicular Pain: A Randomized, Double-Blind,
Active-Control Trial
Babita Ghai, MD1, Dipika Bansal, DM2, Jonan Puni Kay, MD1, Kaivalya Sadashiv Vadaje, MD1,
and Jyotsna Wig, MD1
From: 1Department ofAnaesthesia and Intensive
Care, Post Graduate Instituteof Medical Education andResearch, Chandigarh, India;
2
Clinical Research Unit, National
Institute of Pharmaceutical
Education and Research, Mohali,
Punjab, India
Dr. Ghai is an Additional
Professor, Department ofAnaesthesia and Intensive
Care, Post Graduate Institute ofMedical Education and Research,
Chandigarh, India. Dr. Bansal isan Assistant Professor, ClinicalResearch Unit, National Instituteof Pharmaceutical Education andResearch, Mohali, Punjab, India.
Dr. Kay is an Ex-Junior Resident,
Department of Anaesthesia andIntensive Care, Post Graduate
Institute of Medical Education
and Research, Chandigarh,
India. Dr. Vadaje is an Ex-Senior
Resident, Department ofAnaesthesia and Intensive
Care, Post Graduate Institute ofMedical Education and Research,
Chandigarh, India. Dr. Wig is
Professor and Head, Departmentof Anaesthesia and Intensive
Care, Post Graduate Institute ofMedical Education and Research,
Chandigarh, India.
Address Correspondence:
Dr. Babita Ghai, MD
Additional Professor
Department of Anaesthesia
and Intensive Care
PGIMER, Sector-12,
Chandigarh, India-160012
E-mail: ghaibabita1@gmail.com
Manuscript received:
10-09-2013
Revised manuscript received:
02-04-2014
Accepted for publication:
02-24-2014
Free full manuscript:
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Background: Epidural injections are the most common minimally invasive intervention used to manage
low back pain with lumbosacral radicular pain. It can be delivered through either transforaminal (TF),
interlaminar, or caudal approaches. The TF approach is considered more efficacious than the interlaminar
approach probably because of ventral epidural spread. However, catastrophic complications reportedwith the TF approach have raised concerns regarding its use. These concerns regarding the safety of the
TF approach lead to the search for a technically better route with lesser complications with drug delivery
into the ventral epidural space. The parasagittal interlaminar (PIL) route is reported to have good ventral
epidural spread. However, there is a paucity of literature comparing the effectiveness of PIL with TF.
Objectives: To compare effectiveness of PIL and TF epidural injections for managing low back painwith lumbosacral radicular pain.
Study Design: Randomized, double-blind, active-control study.
Setting: Interventional pain management clinic in a tertiary care center in India.
Methods: Sixty-two patients were randomized to receive fluoroscopically guided epidural injectionof methylprednisolone (80 mg) either through the PIL (n = 32) or TF (n = 30) approach. Patients were
evaluated for effective pain relief (≥ 50% from baseline) by 0 – 100 visual analogue scale (VAS) andfunctional improvement by Modified Oswestry Disability Questionnaire (MODQ) at 2 weeks, 1, 2, 3,
6, 9, and 12 months. Patients who failed to respond to the treatment or when the patient’s response
deteriorated received additional injection of same injectate, dose, and approach. Only if the pain
returns should there be a maximum of 3 injections. Other outcome measures were overall VAS and
MODQ, number of injections, and presence of ventral and perineural spread.
Results: Effective pain relief (≥ 50% pain relief from baseline on VAS) was observed in 76% (90%CI 60.6 – 88.5%) of patients in the TF group and 78% (90% CI 62.8 – 89.3%) of patients in the
PIL (P = 1.00) group at 3 months. The pain relief survival period was comparable in both groups (P =0.98). Significant reduction in VAS and improvement in MODQ were observed at all time points postintervention compared to baseline (P < 0.001) in both groups. On average, patients in the PIL group
received 1.84 and patients in the TF group received 1.92 procedures annually. The majority received
injection at L4-L5 intervertebral level (24 in TF and 23 in PIL). Ventral epidural spread was comparable inboth groups (PIL – 91.6% and TF – 89.6%). No major complications were encountered in either group;
however, initial intravascular spread of contrast was observed in 3 patients in the TF group.
Limitations: Limitations included lack of documentation of adjuvant analgesic drug therapy andprocedures performed by a single experienced interventionalist.
Conclusions: Epidural injection delivered through the PIL approach is equivalent in achieving effective
pain relief and functional improvement to the TF approach for the management of low back pain withlumbosacral radicular pain. The PIL approach can be considered a suitable alternative to the TF approach
for its equivalent effectiveness, probable better safety profile, and technical ease.
Trial registration: CTRI/2012/08/002938.
Key words: Low back pain, lumbosacral radicular pain, interlaminar, parasagittal, transforaminal,
epidural steroid injection, epidural steroids, equivalence clinical trial
Pain Physician 2014; 17:277-290

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Pain Physician: July/August 2014; 17:277-290Low back pain (LBP) with or without involvementof extremities is the most common of all spinal,and even chronic, pain problems (1). Health careexpenditure on its management continues to rise atan unsustainable rate (2-7). It is the most common of
the diseases for the largest number of years lived withdisability in 2010 in US (3). Intervertebral disc herniation(IDH) is the common etiology of lumbosacral radicular
pain (1,2,8,9).
There have been explosive increases in spinal interventional techniques for spinal pain in the US is inpast decade (10,11). Epidural steroid injection (ESI) for
management of lumbosacral radicular pain is minimallyinvasive, effective, and is the most commonly performed
procedure (1,2,10,11). ESI has been associated with substantial debate in reference to effectiveness, appropriate
medical necessity, and indications. According to critics the available evidence suggests that ESIs offer only
short-term relief of leg pain and disability for patientswith sciatica (12). The small size of the treatment effects,
however, raises questions about the clinical utility of thisprocedure in the target population (12). Proponents
argue that there is at least moderate evidence based on
the literature that properly evaluates evidence-based
medicine principles (1,2,10,11,13,14). It is also shownthat local anesthetic with or without steroids is equallyeffective and thus, many clinicians may even avoid steroids (15-18). In addition, a recent systematic review byBicket et al (19) shows an equal or even superior effectof non-steroid injections into the epidural space. On
the contrary, in a proper placebo design Ghahreman etal (20) showed a lack of effectiveness of epidural local
anesthetic and sodium chloride injection when it was injected in or away from the epidural space. They reported
substantial outcome in epidural steroid group and ruledout simply a placebo effect (20).
Most IDHs are located posteriorly in the ventral
epidural space, hence it is suggested that ESI would be
more effective if delivered close to this targeted site
(1,14,21,22). The epidural space in the lumbar spine
can be accessed through interlaminar (IL, either midline or parasagittal), transforaminal (TF), and caudal
approaches (1,2,12-18,21,22). Though the IL approach
is widely used, its efficacy was reported to be limited(22-24). This was mainly ascribed to the use of the midline interlaminar (MIL) approach: lack of target specificity and distribution of injectate into the dorsal rather
than ventrolateral space (25,26). The TF approach isconsidered as target specific (delivering injectate into
the ventrolateral epidural space near nerve root) and278

in the past was reported to be more effective than the
IL route (22-24).
However, recent studies (15,27-29) and recent systematic reviews (30,31) show that IL epidural injections
are as effective as TF injections and equally as effective as
caudal (16) when performed in contemporary interventional pain management settings utilizing fluoroscopy.
Transforaminal ESI is associated with a multitude ofserious complications; the most catastrophic are spinal
cord infarction and permanent paralysis due to intraarterial drug injection and paraplegia (32). Increasing
instances of intradiscal drug injections (33) and evendeath with cervical spine TF injection (34) have also
been reported. The concerns regarding the safety of
TF ESI led to the search for a technically better routewith lesser complications and with drug delivery into
the ventral epidural space.
Lately, good ventral epidural spread (VESp) of contrast is reported while using a modified interlaminar
approach, i.e. parasagittal interlaminar (PIL) (35) or
lumbar interlaminar ventral epidural (LIVE) injections
by placing an epidural catheter at the ventrolateralside of the nerve root (36). However, these studies investigated contrast spread as the primary outcome. The
clinical significance was either not elucidated (36) or
was limited by the observational uncontrolled nature(35), as Candido et al (35) only controlled the first intervention for each patient and additional treatment
decisions were made on a case to case basis, limiting
their ability to evaluate the efficacy of one techniqueover another. While assessing the clinical outcome of
PIL with a MIL approach of ESI, our group has recently
reported more effective pain relief at 6 months andbetter VESp of injectate (89.7% versus 31.5% in MIL)
with a PIL approach compared to MIL (21).
There is a paucity of literature regarding the head
to head comparison of PIL with TF ESI for the management of chronic LBP (CLBP) with radicular pain. Thusin view of this, the current study was conducted tocompare the effectiveness and safety of fluoroscopically guided TF ESI with PIL ESI for managing CLBP withunilateral lumbosacral radicular pain secondary to IDH
not responding to conservative management.

Methods
Study Design
This was a prospective, single center, randomized,
double-blind, active-controlled parallel group clinical
trial. The study was conducted in accordance with thewww.painphysicianjournal.com

Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

Consolidated Standards of Reporting Trials (CONSORT)
guidelines (37) and following the principles of the
Declaration of Helsinki. The study was approved by the
PGIMER institutional review board (Chandigarh, India),
and all patients provided written, informed consent. The
trial was registered with the Clinical Trial Registry of India(CTRI) with an assigned number of CTRI/2012/08/002938.

Patients
The study setting was a public sector interventional
pain management specialty referral clinic in a tertiarycare hospital in India. Adult patients of either gender,
aged 18 to 65 years, with a diagnosis of CLBP and unilateral lumbosacral radicular pain, with a minimum of
3 months duration not responding to medications andphysical therapies, having a pain score of at least 50 asassessed on 0 – 100 Visual Analogue scale (VAS) at baseline were eligible for study recruitment. The diagnostic
criteria for lumbosacral radicular pain were discussed
previously (1,38). Patients were clinically examined
including straight leg raising test. Magnetic resonanceimaging (MRI) was performed to correlate the symptomatology and exact disc level protrusion.
Patients were excluded if they had any clinicallysignificant or unstable medical or psychiatric illness, previous surgery on the lumbar spine, facet joint arthropathy, spinal canal stenosis, unstable neurological deficits,
or cauda equine syndrome. Those having received lumbar ESI in the past, corticosteroids or anesthetics allergy,
taking anticoagulants or bleeding diathesis, taking systemic corticosteroids, pregnant and lactating women,or those being treated with investigational drug within
30 days of trial were also excluded.

Randomization and Masking
Patients were randomized to receive ESI througheither the TF or PIL approach. Randomization was performed by an independent pharmacist using a computer
generated randomization schedule (Software RandomRandomizer, blocks of six). Random numbers were kept
in opaque sealed envelopes and opened by an independent anesthesiologist at the time of injection. None of
the study investigators, including the outcome assessor,
had access to the randomization sequence. All procedures were performed by single investigator (BG) andfollowed by other investigators (DB/JPK). Study cases
were kept in between clinical non study cases during
the procedure as well as for follow-up. It was done toenhance the blinding and allocation concealment.

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Study Interventions and Procedures
Before the intervention, intravenous access andstandard monitoring was established. The intervertebral level was determined by clinical examination and
MRI studies. All procedures were performed underC-arm fluoroscopic guidance. Initial anteroposterior(AP) images were obtained to identify the level andinterlaminar space in a prone position with a pillowof 10 cm height kept under the abdomen.
In the PIL group, an 18-gauge, 3.5 inches, Tuohy
needle was introduced at the level of disc pathology
and advanced in a posterior to anterior direction. The
needle was introduced into the most lateral epiduralspace of the affected side, using the loss-of- resistanceto saline technique and this parasagittal orientationof the needle was maintained throughout the procedure (21) (Fig. 1A).
In the TF group, a 22-gauge, 3.5 inch Quincke’s
needle was introduced at the level of disc pathology
using first an AP and, subsequently, an oblique orientation (15 – 300) of the fluoroscopy C-arm to achieve
the “Scotty Dog” appearance of the lumbar spine andthen directed until the needle tip was in the posteriorand superior aspect of the intervertebral foramen as
checked in the lateral imaging, and in line with thepedicle on AP view (39) (Fig. 1B).
In both groups, once the needle was in position, and after negative aspiration for cerebrospinal
fluid and blood, 0.5 mL Iohexol (300 mg/mL), (OMNIPAQUE™, GE Healthcare, UK) was injected to confirm
the epidural space in the AP view. This was followed
by further injection of 3.5 mL of contrast under continuous fluoroscopy to confirm the spread of thecontrast as well as to verify that no contrast medium
attained the intra vascular, subarachnoid, subdural, or
intra-discal spread (Figs. 2A, 2B). Lateral images weretaken to evaluate the ventral epidural space. Ventral
spread was defined as present if contrast travelledalong the posterior longitudinal ligament or abutted
the posterior aspect of the contiguous vertebral bodyat the level of needle insertion (Figs. 3A, 3B). Perineural spread and segmental spread was also noted on APview (Figs. 2A, 2B). After epidural space confirmation,
2 mL of methylprednisolone acetate (l mL = 40mg)(DEPO-MEDROL™ injection, Pfizer products India Pvt.
Ltd, Mumbai) with 2 mL sterile normal saline were
injected.
All the patients were kept under observation for
at least 30 minutes post-procedure.

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Pain Physician: July/August 2014; 17:277-290

A

B

Fig. 1. A. Parasagittal interlaminar approach. AP view showing the needle placement at the lateral most part of L4-L5
interlaminar area. B. Oblique view showing “Scotty Dog” appearance of vertebra and needle insertion for transforaminal approach
between L4-L5.

A
B
Fig. 2. A. Confirmation of needle with parasaggital interlaminar approach. AP view of contrast showing epidural as well as
perineural spread of contrast of the same side (arrow). B. Confirmation of needle with transforaminal approach. AP view ofcontrast showing epidural as well as perineural spread of contrast of the same side (arrow).

Assessment and Follow-up
Patients were assessed for pain by VAS on a horizontal 0 (no pain) to 100 (worst pain possible) scale andfor functional impairment using modified Oswestry Disability Questionnaire (MODQ) (40) at 2 weeks, 1, 2, 3,

280

6, 9, and 12 months post-intervention. We defined theapproach as “effective” when pain relief was a ≥ 50%
reduction from baseline on VAS. The primary endpoint
was effective pain relief at 3 months. However, pain
relief and MODQ were assessed continuously for 12

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Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

A

B

Fig. 3. A. Lateral view of parasagittal interlaminar approach.Ventral epidural spread is indicated by arrows. B. Lateral view oftransforaminal approach approach. Ventral epidural spread is indicated by arrows.

months of follow-up at above mentioned time points.
Patients’ self-evaluation of overall change was doneon the basis of a 7-point Patient Global Impression of
Change (PGIC) (41) at 3, 6, and 12 months post-intervention. Patients were also assessed for possible neurologic complications and any newly developed pain.
Patients who failed to respond to the treatment
or patients whose response deteriorated received additional injection of same injectate, dose, and approach.
Only if the pain returns should there be a maximum of
3 injections. The minimum time between the 2 injections (if required) was 15 days.

Co-Interventions and Post-intervention
Medications
All study patients were receiving conservative
management including analgesics (adjuvant; pregabalin, opioid, or non-opioid) and/or an exercise program
before joining the study. Exercise programs continued
and analgesics continued/reduced/increased as perneed. Job attendance continued. The only new treatment introduced was the study intervention.

Primary and Secondary Endpoints
The proportion of patients achieving effective pain
relief at 3 months in each group was considered as thewww.painphysicianjournal.com

primary endpoint. The secondary endpoints included
overall mean pain and MODQ scores at various time
points, PGIC score, presence of ventral and perineuralspread, segmental spread, number of injections required, treatment emergent adverse events (TEAEs),and possibly neurological complications as assessed byclinical and laboratory evaluation.

Statistical Analysis
Sample size was calculated assuming both approaches providing pain relief at 3 months to the tuneof 75% (15,21,42) and largest clinically acceptable effect to be able to declare equivalence is 15% so that90% confidence interval (CI) of proportion of effective
pain relief in each group should lie between 60% and90%. True mean difference between the 2 approaches
is thought to be zero with equal group allocation,
probability of type I error of 2.5% at each side, power
90%; we got a sample size of 27 patients to be recruitedin each arm. We recruited 62 patients for possible dropouts.
Data are presented as mean with standard deviation (SD) or median with interquartile range (IQR). Demographic data were analyzed using either 2 sample
independent student t-tests or χ 2 tests. The primary
endpoint was analyzed by χ 2 test. Two-way repeated281Pain Physician: July/August 2014; 17:277-290

measures analysis of variance (ANOVA) was used toanalyze VAS and MODQ over time within and between
groups. Greenhouse-Geisser test was used with adjustment for time × factor, time × group interaction, andbetween-subject effects for VAS and MODQ followed
by Bonferroni correction for multiple comparisons. Effective pain relief duration was analyzed using KaplanMeier survival analysis. Clopper-Pearson Exact method
was used to find the 90% CI of effective pain relief
proportion and upper limit of 95% CI of complications.
PGIC was assessed using Mc-Nemar Bowker test. Statistical software SPSS version 15.0 (SPSS Inc, Chicago,IL) was used for analysis. P < 0.05 was consideredsignificant.

Results
Patient Disposition
The study period was October 2011 to April
2013. Patients’ clinical characteristics, demography,
and disposition through the study period are summarized in Table 1 and Fig. 4, respectively. One hundred
twenty-four patients were screened and 62 patients(n = 30 in the TF group and n = 32 in the PIL group)
were included in the study. All included patients wereavailable for complete follow-up. Both groups weresimilar with respect to pre-procedure characteristics(Table 1).

Primary Outcome
Effective pain relief at 3 months was 76% (90% CI
60.6% – 88.5%) in the TF group and 78% (90% CI 62.8%– 89.3%) in the PIL group (= 1.00). Thus, the proportionof relief was within equivalence width in the 2 groups.
The proportion of subjects achieving effective pain relief (Fig. 5) at 2 weeks, 1, 2, 3, 6, and 12 months werealso comparable in both groups.

Effective Pain Relief Survival Analysis
Kaplan-Meier curves (Fig. 6) for effective pain relief
survival were found to be comparable in both groups,
showing that effective pain relief survival period was
similarly achieved with both approaches (P = 0.98).

PGIC
Overall, 24 of 30 patients in the TF group and 25 of
32 patients in the PIL group improved with ESI over 52
weeks of follow-up on the PGIC scale (Table 2) (P > 0.05
at all time points). One in each group did not achieve
any pain relief despite receiving 3 ESIs. This patient in
the PIL group had surgery at 9 months.

VAS and MODQ Score Over Time
Repeated measures ANOVA revealed time × factor (P < 0.001 for both VAS and ODQ) interaction but
no time×group interaction (P = 0.79 for VAS and P =0.68 for ODQ). Between-group effect was not found tobe significant (P = 0.58 for VAS and P = 0.34 for ODQ).
Follow-up within group pairwise analysis revealed
that VAS and MODQ decreased significantly at all timeintervals compared with baseline in both groups (P <0.001, Figs. 7 and 8). Between-group analysis revealed
that VAS and MODQ scores were comparable in the 2groups at all time intervals (Figs. 7 and 8).

Table 1. Baseline demographic characteristics.

TF Group(n = 30)

PIL Group (n = 32)

P value

Mean ± SD

46.1 ± 12.5

42.8 ± 9.6

0.07

Male

19 (63%)17 (53%)

Female11 (37%)15 (47%)Weight ( kg)

Mean ± SD

67.7 ± 12.1

65.3 ± 9.3

0.68

Height (cm)Mean ± SD

170.0 ± 7.6

168.4 ± 6.3

0.28

Body mass Index (kg/m2)

Mean ± SD

23.4 ± 3.785

23.0 ± 3.11

0.85

Duration of pain (months)

Mean ± SD
Median (IQR)

30.2 ± 65.8
12 (10–24)

25.1 ± 25.9
12 (10 – 36)

0.37

Visual Analogue scale (0 – 100)

Mean ± SD
Median (IQR)

73.5 ± 1.19
70.1 (70 – 80)

73.1 ± 0.99
70 (62.5 – 80)

0.57

Modified Oswestry Disability score

Mean ± SD
Median (IQR)

28.93± 5.97
30 (25.75 – 30.50)

31.3 ± 7.78
31 (26.75 – 35.25)

0.27

Age (years)
Gender282

0.42

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Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

Fig. 4. Flow chart of patients who participated in the study.

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Pain Physician: July/August 2014; 17:277-290

TF: Transforaminal, PIL: Parasaggital interlaminar. Compared using chi-square test,* P <0.05 within groups compared to baseline. As assessedusing VAS (≥ 50% reduction from baseline). None of the groups were significantly different at any time point.

Fig. 5. Effective pain relief incidence over the 52 weeks of follow-up.
Table 2. Patient Global Impression of Change (PGIC).

TF Group(n = 30)

PGIC

PIL group(n = 32)

P valueMonths

Improved

No change

Worse

Improved

No change

worse

3

23

4

3

25

6

1

0.49

6

24

3

3

24

7

1

0.28

9

23

6

1

25

6

1

0.99

12

24

5

1

25

6

1

0.98

PGIC is a 7-point scale on which patients rated change in overall status since study start (1 – 3 = improved, 4 = no change, 5–7 = worse).
Compared by McNemar Bowker test.

Table 3. Intervertebral disc herniation involved level and level of injection.

Level of disc herniation and injection

284

TF group (n = 30)

PIL group (n = 32)

L3-L4

3

4

L4-L5

24

23

L5-S1

3

5

P value

0.52

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Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

Level of Injection
Levels of injections in both groups
were comparable. The majority received
ESIs at the L4-L5 level (24 in the TF groupand 23 in the PIL group). Three patientsin the TF group and 4 in the PIL group received injection at the L3-L4 level. Threepatients in the TF group and 5 patientsin the PIL group received injection at the
L5-S1 level (P = 0.52) (Table 3).

Total Number of ESI
Total ESIs administered in the TF
group (60) and the PIL group (58) werecomparable (P = 0.72) with 1.92 procedures in the TF group and 1.84 procedures in PIL group per year. Nine (30%)
in the TF group compared to 12 (37.5%)in the PIL group (P = 0.59) received only
one injection. Twenty-one patients in
the TF group and 20 patients in the PIL
group received further injections. Twelve

Fig. 6. Kaplan-Meier graph for effective analgesia period. This figure
represents probability of patients having effective analgesia at different pointsof time.

Error bars represents standard deviation. *P value at different time intervals as compared with baseline (withingroup, pair-wise comparisons with Bonferroni correction) #1 P = 0.56, #2 P = 0.63, #3 P=0.61, #4 P = 0.59,#5 P = 0.64, #6 P = 0.56, #7P=0.23 and #8P= 0.79, respectively, for between-group comparisons at specified
time intervals with Bonferroni correction.
TF; Transforaminal, PIL; Parasaggital interlaminar

Fig. 7. Mean Visual Analogue Scale score over time.

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Pain Physician: July/August 2014; 17:277-290

Error bars represents standard deviation. *P value at different time intervals as compared with baseline (withingroup, pair-wise comparisons with Bonferroni correction) ) #1 P = 0.18, #2 P = 0.29, #3 P=0.38, #4 P = 0.38,#5 P = 0.60, #6 P = 0.36, #7P=0.52 and #8P= 0.45, respectively, for between-group comparisons at specified
time intervals with Bonferroni correction.
TF; Transforaminal, PIL; Parasaggital interlaminar

Fig. 8.Mean Modified Oswestry Disability Questionnaire score over timeof 21 in the TF group and 14 of 20 in the PIL group
achieved effective pain relief after a second injection.
Nine in the TF group and 6 in the PIL group received 3
injections (P = 0.57).

Ventral Epidural and Perineural Spread
VESp was comparable, 89.6% (52 of 58 injections)in the TF group as compared to 91.6% (55 of 60 injections) in the PIL group (P = 0.64). Incidence of perineural spread was significantly higher in the TF group, i.e.
95% (57 of 60 injections) compared to 62% (36 of 58
injections) in the PIL group (P < 0.001).

Fluoroscopy Time
Fluoroscopy time in both groups was comparable.
Mean (SD) fluoroscopy time after all injections was
16.21 (5.44) seconds and 13.89 (6.7) seconds in the TF
and PIL groups, respectively (P = 0.25).

Monitoring of the Complications
No intrathecal, intradiscal, or subdural contrast
placement was encountered. Intravascular spread ofcontrast was noted during 3 injections (5.1%) in the TF
group. Ninety-five percent CI was 0.0% – 10.8% in the286

PIL group and 0.0% – 11.6% in the TF group, and 0.0%
– 5.8% for both groups together. Needle relocation at
the desired site was required in both groups. In the TF
group it was required in 3 patients due to intravascularspread and in the PIL group it was required during 3
injections as the needle was not at the lateral-most site.
No patient reported any swelling, redness, or persisting
pain at the injection site. Un-masking was not required
for any patient.

Discussion
The study revealed comparable health benefits
with both the PIL and TF approach with respect toeffective pain relief for managing patients with CLBP
with unilateral lumbosacral radicular pain. Significant
improvement was observed with both approaches
in primary as well as secondary outcomes, including
functional disability (MODQ), pain intensity (VAS), andimprovement ratings (PGIC) in both groups.
Among various approaches for ESI, TF was considered as target specific and more effective as compared
to IL in the past (14,22-24). This may be due to blindadministration of IL or needle placement in the dorsal
space under fluoroscopic guidance leading to limited

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Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

VESp of steroid (28% – 47% only) (25,26). Studies havesuggested the superiority of TF ESIs for both short andlong-term outcomes (14,22-24). A retrospective study
by Schaufele et al (22), assessing pain improvement andsurgical rates for managing lumbar IDH between IL and
TF injection over 18 months, reported TF ESI’s superiority
in short-term pain improvement and long-term surgicalinterventions. Ackerman and Ahmad (23), comparing
efficacy of 3 fluoroscopically guided approaches (TF, IL,
and caudal ESI) in patients with IDH, demonstrated TF
ESI’s superiority to IL ESI for lumbar radicular pain relief.
They attributed this to higher VESp while using the TF
approach. An advantage of TF ESI is that it can be performed in patients with failed back surgery syndromeat the levels of surgeries.
However, recent studies (15,27-29) and systematic reviews (30,31) show an equivalence of IL and TF injections.
Rados et al (27), while comparing TF and IL approaches
in patients with chronic unilateral radiculopathy, demonstrated significant functional and pain improvementwith both approaches. Gharibo et al (28), while comparing IL and TF techniques in patients with subacute unilateral radiculopathy, reported comparable significant
improvements in pain, function, and depression. The IL
was entered through the epidural space with a paramedian approach and ipsilateral spread was confirmed. The
authors concluded that IL could be the initial technique
because of better safety and less patient discomfort.
Manchikanti et al (15), while evaluating the effectiveness of a single injection of lumbar interlaminar local
anesthetics (LA) with or without steroids for managing
chronic pain of IDH or radiculitis, reported significant
pain relief in 74% patients treated with LA and 86%
with LA and steroids. The epidural space was enteredat the L5/S1 level or at a level below the pathology todirect contrast flow toward herniated disc side. Furman
et al (29) evaluated the effect of ESI using a paramedian
IL approach for lumbar radicular pain and showed pain
improvement for at least 3 months.
In these later studies, IL techniques might haveoutperformed previous studies due to a lateral paramedian/parasagittal interlaminar approach (leftward
or right, toward the side of complaint) compared to a
traditional midline approach (15,28,29). However, final
position of the needle in the epidural space during an IL
approach was not clearly mentioned (15,28,29), though
there were attempts to have the contrast spread on affected side which could influence drug spread.
The TF approach is associated with a higher incidence of serious complications due the anatomical rela-www.painphysicianjournal.com

tion of the radicular artery accompanying nerve root(32). The most devastating complication is intravascular
injection leading to spinal cord infarction and permanent paralysis. At least 18 cases of permanent paralysis
are reported following TF ESI in the literature (32). On
the contrary, only 2 MRI confirmed reports of spinal
cord infarct are reported with lumbar IL ESI (43,44). In
both cases, patients had prior surgery at the level of the
IL ESI and in one a 21gauge intramuscular needle wasused instead of an epidural needle (43). Post-surgicalchanges in the epidural space, arterial spinal vasculature (43,44), and use of an intramuscular needle (43)might have contributed to this complication. Also, overall rate of intravascular injection with lumbosacral TF
ESIs is reported to be 11.2% (45) as compared to 1.9%(46) with IL ESI. Other complications reported with TF
ESI are a 10-fold increased incidence of intradiscal injection, hence higher risk of discitis (33) and even deathwith cervical injection (34). Higher occurrence of serious
complications have raised concerns regarding the safetyof TF ESI and led to a search for alternative techniques
for better VESp with fewer complications.
Lately, good VESp is reported when the needle
was placed in the lateral most part of the epiduralspace (35,36). Candido et al (35) demonstrated 100%
VESp with the PIL approach and 75% spread with the
TF approach. Choi and Barbella (36) reported VESp inall patients using the LIVE approach of injection. However, these studies investigated contrast spread as theprimary outcome. The clinical significance was either
not elucidated (36) or was limited by the observational
uncontrolled nature (35). We recently evaluated clinical significance of PIL with MIL approach and reported
that PIL was superior to the MIL approach (21). The PIL
approach provided more patients with effective pain
relief (68.4% vs 16.7% at 6 months), better VESp (89.7%
versus 31.7% in MIL), better functional improvement,
and less number of injections (21).
In the present study, VESp with the TF approach
was 89.6% and 91.6% with the PIL approach. Thesefindings are in accordance with previous studies (21,23).
Good VESp in both groups might have produced equivalent clinical outcomes. We performed all interventions
under fluoroscopy and did not encounter contrast
spread to the intradiscal, subarachnoid, or subduralspaces. Intravascular contrast spread was observed during 3 injections (5.1%) in the TF group requiring needle
relocation.
The IL technique is a part of the anesthesia residency program in a majority of countries. However, TF

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Pain Physician: July/August 2014; 17:277-290

ESI requires super specialized training during a chronic
pain management curriculum. This can be consideredadvantageous with an anesthesiologist performinginterventional pain management procedures. However, this may not be relevant with other specialists
such as physiatrists, neurologists, neurosurgeons, andorthopedic surgeons joining the interventional pain
management specialty. Also, the S1 foramen is slightly
more difficult to access technically (47). AP view of the
S1 foramen is not always predictable as the more easily seen foramen is the ventral foramen (47). In the APview, while lining up ventral and dorsal S1 foramen,
accidental needle tip placement anterior to the ventral
foramen is possible with gastrointestinal penetration,
whereas in the oblique view, the iliac crest may obstruct
the path of the S1 foramen (47). An L5-S1 IL procedure
is not hampered by these difficulties. Hence in the scenario of equivalent efficacy with both approaches, withthe perceived advantages of the PIL approach such astechnical ease, training at specialty rather than super
specialty level, and probably better safety profile, thePIL approach can be considered as an alternative to the
TF approach or as the first choice for administering ESI
to patients with CLBP with lumbosacral radicular pain.

Strengths and Limitations
The strengths include high internal validity; treatments provided according to protocols; effective masking of interventionialist, patients, and assessors; consistent retention of patients throughout the study; andadequate sample size for a well powered equivalencetrial.
Limitations included lack of documentation of
adjuvant therapies like individual patient exercise routines and analgesic drug therapy. Additional betweengroup variability might have remained unadjusted.
Other limitations are the utilization of a high volume
contrast and a high volume mixture of methylprednisolone and sodium chloride solution as well as a lackof local anesthetic injection. We used total of 4 mL ofcontrast which was equal to the volume of the drug
used for injection. This amount of contrast and drug iswithin the range of volume used by previous investigators (16,17,29,35). Also, saline was added to dilute polyethylene glycol 4000 (28.6 mg/mL), the vehicle added
during the manufacture of methylprednisolone thathas been implicated to be associated with arachnoiditis(35). Since all procedures were performed by a single

288

experienced interventionialist (with an experience ofaround 10 years), generalization of these results performed by less experienced interventionialists remains
yet to be established. Wider implications of this trial canonly be extrapolated by conducting a clinic based study
with the interventions performed by interventionists
with different ranges of experience. The challenges in
the implementation of these findings in clinical services
are well appreciated and that our results might not be
generalized to non-specialized health care settings or
non-specific LBP patients.

Conclusion
ESI is comparable with TF and PIL approaches under fluoroscopic guidance for achieving effective pain
relief and functional improvement over 12 months for
managing CLBP with unilateral radicular pain with therequirement of a comparable number of injections. ESI
was without any complications with both approaches.
The equivalent clinical outcomes with both approaches
are most probably due to similar VESp. The PIL approachcan either be a suitable alternative to the TF approachor the first choice for its probable better safety profileand technical ease.

Acknowledgments
Dr. Babita Ghai had full access to all the data in the
study and takes responsibility for the integrity of thedata and the accuracy of the data analysis. Drs. Babita
Ghai and Dipika Bansal designed the study protocol. Dr.
Jonan Puni Kay and Kaivalya Sadashiv Vadaje managed
the literature searches and summaries of previous related work and wrote the first draft of the manuscript. Dr.
Jyotsna Wig provided revision for intellectual content
and final approval of the manuscript.
All authors have no conflicts of interest to report.
None of the authors of the manuscript received any
remuneration. Further, the authors have not received
any reimbursement or honorarium in any other manner. The authors are not affiliated in any manner withany pharmaceutical company/industry. However, all
the authors are members of the public tertiary care/research institute and are practicing interventional pain
physicians except for Dipika Bansal, who is a clinicalpharmacologist.
The study was conducted by Babita Ghai, Dipika
Bansal, Jonan Puni Kay, Kaivalya Sadashiv Vadaje, andJyotsna Wig­­­­.

www.painphysicianjournal.com

Transforaminal versus Parasagittal Interlaminar Epidural Steroid Injection for Radicular Pain

We also would like to thank the editorial board of
Pain Physician for review and criticism in improving themanuscript.
Disclaimer: There was no external funding in the
preparation of this manuscript.
Conflict of interest: Each author certifies that he orshe, or a member of his or her immediate family, has nocommercial association (i.e., consultancies, stock ownership, equity interest, patent/licensing arrangements,etc.) that might pose a conflict of interest in connection
with the submitted manuscript.

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