Indian Journal of Pain

: 2018  |  Volume : 32  |  Issue : 3  |  Page : 155--162

Image guided trans foraminal epidural injection: Is it a viable stopgap therapy for low backache

Samaresh Sahu1, Rochan Pant2, Sashank Sharma3,  
1 Department of Radiodiagnosis and Imaging, Command Hospital Air Force, Bengaluru, Karnataka, India
2 Department of Radiodiagnosis and Imaging, Military Hospital Cardiothoracic Centre, Pune, Maharashtra, India
3 Department of Radiodiagnosis and Imaging, KGMC Lucknow, Uttar Pradesh, India

Correspondence Address:
Dr. Samaresh Sahu
Department of Radiodiagnosis and Imaging, Command Hospital Air Force, Agram Post, Bengaluru - 560 007, Karnataka


Aims: 1. Study the change in pain and function in patient with lumbosacral disc disease on MRI using visual analogue scale (VAS) and the revised Oswestry disability index (ODI) for back pain after administration of fluoroscopically guided transforaminal epidural injection. 2. Correlate the response of the patient with the spread of contrast in epidural space. Method: 100 patients with history of low back ache and imaging findings of disc herniation were enrolled based on inclusion criteria. Patients scored their pain on the VAS and functional disability on revised ODI. The patient was evaluated for distribution of pain and was administered a combination of anaesthetic and steroid after confirming the position of the tip of needle using iodinated contrast. Follow up for response to pain and improvement in disability in immediate post procedure done at 3 and 6 months. Result: 102 injections were administered for 100 patients which comprised of n=69 {67.6%} male and 33{32.4%} female and age distribution was 21-79 years. The distribution of indication was disc bulge n=29 (28.4%), extrusion n=12 (11.8%), post operative n=19 (18.6%), protrusion n=42 (41.2%). No significant difference between the VAS scores (p=0.20) of the individual indication pre procedure. After 3 & 6 months there was statistically significant difference between the mean rank value of population indicating maximum benefit for disc bulge population and least for post operative population at three months follow up. Conclusion: There is statistically proven good results in all cases for 6 months, after which repeat injections may be tried.

How to cite this article:
Sahu S, Pant R, Sharma S. Image guided trans foraminal epidural injection: Is it a viable stopgap therapy for low backache.Indian J Pain 2018;32:155-162

How to cite this URL:
Sahu S, Pant R, Sharma S. Image guided trans foraminal epidural injection: Is it a viable stopgap therapy for low backache. Indian J Pain [serial online] 2018 [cited 2020 Jul 10 ];32:155-162
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Full Text


Back pain has been the nemesis of mankind and has been one of the most frequently reported symptoms in the industrialized world.[1] The annual cost of disease in terms of loss of man-hours and managing it runs in tens of billions of dollars in the USA alone.[2]

Backache is a symptom with the underlying disease process involving various parts of the spine such as bone, joint, synovium, or the disc. Intervertebral disc prolapse which accounts for 42% of causes of low backache is one of the major causes.[3]

Low backache that continues for more than 7–12 weeks despite having taken adequate conservative therapy is termed as chronic.[4] The prevalence of nonspecific low backache is around 15% while it increases with age to 44% at 70 years.[5] Transforaminal epidural injection (TFEI) is a method used for pain relief in patients with radicular discogenic pain. These injections provide a pain-free window for the patient to be mobilized for physiotherapy and hence break the pain cycle.

The literature is full of varied opinions, controversies, and findings about the usefulness of TFEI. In this background, we carried out a study at our tertiary care center to evaluate TFEI in the management of low backache.

Aims and objectives

The objective of the study is to study the change in pain and function in a patient with lumbosacral disc disease proven on magnetic resonance imaging (MRI) using visual analog scale (VAS) and the revised Oswestry Disability Index (ODI) for back pain after administration of fluoroscopically guided contrast-enhanced TFEI, to correlate the response of a patient with their MRI findings, and to correlate the response of the patient with the spread of contrast in epidural space.

 Materials and Methods

This study was conducted in the Department of Radiodiagnosis and Imaging and Intervention at a tertiary care hospital from December 2014 to June 2016.


One hundred patients who were referred to us from the Department of Neurosurgery who failed to respond to a trial of conservative management for at least 6 weeks were offered TFEI. These patients who accepted and gave their consent for the study were followed up and evaluated over a period of 6 months from the date of injection for pain relief and functional improvement on the VAS [Appendix 1] and modified ODI for a backache.[INLINE:1]

Primary Outcome: Pain relief using VAS.

Secondary Outcome: Functional change using revised ODI for back pain.

Inclusion criteria

Selected patients complained of low backache for a minimum of 12 weeks and showed no improvement with conservative therapy to NSAIDS and physiotherapy for at least 6 weeksPatients of 18 years and above of either sexPatients with clinical symptoms of radiculitisMRI proven lumbar disc herniationPatients with central or foraminal stenosis.

Exclusion criteria

Patient unable to provide informed consentPatients with significant coagulopathies and using anticoagulantsPatient with history of allergy to contrast media, steroids, and local anesthetic agentsPatient diagnosed to have active cancer, history of substance abuse, current psychiatric comorbidity, pregnancy, diabetes mellitus, and congestive cardiac failureUnstable spine, vertebral compression fractures, spondylolisthesis, cauda equina syndrome, facet joint arthropathy, and arachnoiditis.

Test applied

VAS and “the Revised ODI for low back pain” scores were used for each patient, and they were enrolled for the study (preprocedure). The same tests were used again postinjection immediately after the patient came out of the intervention of suite so as to assess the immediate effect. The pain score and disability indexes were also repeated at three and 6 months as the patients reported to intervention outpatient for follow-up.

The patients were explained about the procedure and were asked if they would volunteer for the study. Individuals who consented to participate in the study were asked to sign a consent and were asked to mark on a piece of paper how they rated the pain on the ten point VAS; their functional outcome was assessed using the revised ODI for backache. A total of 102 patients had volunteered and consented for the study over a period of 18 months. Their preprocedure MRI reports were compiled, categorized, and response to therapy was evaluated.

Technique of administering transforaminal epidural steroid injection

Materials required

Nonionic iodinated Contrast media (Iohexol 300 mg/ml of iodine)C-arm for fluoroscopic guidance0.5% Bupivacaine (5 mg/ml)Methyl prednisolone (40 mg/ml) 80 mg.

Transforaminal approach was used by experienced interventional radiologist with 15 years' experience. Modified Antero-posterior (AP) paramedian double needle technique was used (where applicable) where two needles were used simultaneously at the same level if the radicular pain was bilateral. This helped us to gauge the exact extent of spread of contrast and hence predict the spread of drug.

Under fluoroscopic guidance, the epidural space was carefully entered, and non-ionic iodinated contrast was injected to confirm adequate needle placement and spread of contrast in the epidural space to avoid any inadvertent intravascular injection. A note of the spread along the dural sleeve was noted and image recorded for further evaluation [Figure 1], [Figure 2], [Figure 3].{Figure 1}{Figure 2}{Figure 3}

Following this, a mixture constituted containing 0.5 ml of 0.5% bupivacaine (5 mg/ml) and 1cc of methyl prednisolone (40 mg/ml) per site was injected in the epidural sleeve surrounding the nerve root using the transforaminal approach.

A subset of patients when reviewed and did not respond to first instances of TFEI based on the VAS score, were advised for repeat injection on their follow-up visit. In no case, a third injection was given to any patient.

We asked our patients to mark their appreciated pain levels on a 10-point VAS scale and calculated their functional disability according to the revised ODI. There were no dropouts from the study.

Test of statistical significance

The various VAS and revised ODI scores were compiled and segregated. The MRI findings of lumbar spine were entered, and correlation of the score for the groups was done using one-way analysis of variance. F values and corresponding P values were drawn and pre- and post-intervention changes were recorded. The response of various types of disc herniation was assessed.

 Results and Statistical Analysis

We studied a total of 102 patients (n = 69 [67.6%] males and 33 [32.4%] females) with an age distribution of 21–79 years; mean age of the population was 45.31 years (standard deviation [SD] = 15.2).

Number of injections received

Out of 102 patients enrolled for our study, 84 were administered one injection while 18 were administered two injections. Mean number of injections administered was 1.17.

Distribution of indication in the study population

The distribution of the indication in the study population (n = 102) according to MRI findings was broadly classified as disc bulge n = 29 (28.4%), extrusion n = 12 (11.8%), postoperative n = 19 (18.6%), and protrusion n = 42 (41.2%).

Pre- and post-procedure VAS score and revised ODI scores for backache were evaluated for all the indications. F score was calculated from the mean rank scores.


There was no significant difference between the VAS scores (P = 0.20) of the individual indication in the preprocedure evaluation. Preprocedure mean rank was lowest for disc bulge patients whereas postoperative patients had the highest mean rank VAS [Table 1].{Table 1}

For the pooled population, there was a significant difference noted between pre-TFEI and Post-TFEI VAS scores [Table 2].{Table 2}

On 6-month follow-up, the mean ranks of the groups followed the same trend with minimum mean rank for diffuse disc bulge indicating that the maximum benefit post-TFEI was noted in diffuse disc bulge and minimum benefit for postoperative population [Table 3].{Table 3}

For the whole population, however, there was a significant change in the pre-TFEI ODI score and post-TFEI ODI score as indicated by F value [Table 4].{Table 4}

Statistical analysis according to indication

The study population was allocated groups depending on their MRI findings and indication of epidural injections.

Disc bulge

Volunteers who had disc bulge as primary pathologies (n = 29) had a mean age of 40.7 years with age distribution of 24–73 years; sex distribution showed a male predisposition with male = 21 (72.4%) and female = 8 (27.6%).

The group with diffuse disc bulge showed a significant change in pre- and post-VAS values [Table 5].{Table 5}

Revised ODI correlated with the finding of VAS, mean rank pre-TFEI ODI showing a significant change in pre- and post-ODI value [Table 6].{Table 6}


Patients (n = 12; male = 9 [75%] and female = 3 [25%]) who had extrusion as the main imaging finding had an age distribution of 21–73 years with a mean age of 51 years and SD of 19.02 [Figure 4]a, [Figure 4]b, [Figure 4]c.{Figure 4}

In this group, the mean rank of VAS score also showed a significant change in pre- and post-VAS values [Table 7].{Table 7}

Revised ODI for this group showed that mean ODI score before injection was 29.17. At 3 months, it was 10.92. At 6 months, it was 12.47. F =11.6 and P < 0.0001 [Table 8].{Table 8}


Postoperative group consisted of patients who had previously been operated for disc-related problems and presented to us with back pain. There were 19 patients in this group with an age distribution 30–79 years, mean age was 50.9 years with an SD of 15.2 years. The sex distribution of males n = 14 (73.7%) and females n = 5 (26.3%).

In this group, a significant difference within the pre- and post-procedure VAS scores in the population [Table 9].{Table 9}

Revised ODI score for these patients showed a significant difference within the group [Table 10].{Table 10}


The group of individuals having findings of the protrusion on MRI had 42 volunteers with age distribution of 25–75 years. The mean age was 44.2yrs with SD of 13.2 years. The sex distribution of male = 25 (59.5%) and female = 17 (40.5%) [Figure 5]a and [Figure 5]b.{Figure 5}

In this group, preprocedure VAS showed a significant change in the pre- and post-TFEI VAS score [Table 11].{Table 11}

The distribution of revised ODI significant change from preprocedure evaluation to postprocedure evaluation [Table 12].{Table 12}

Correlation with contrast spread

Our study used contrast spread as an endpoint for effective installation of the drug in the epidural space. The spread of contrast was noted in all the patients who received the injection.


Epidural steroid injections have a long history of usage. Studies which have been published show variable results and equal efficacies for all the techniques.

Types of epidural injections for pain relief:

TFEIInterlaminarCaudal approach.[6]

Principle and target

TFEI targets the dorsal root ganglion and anterior epidural Fspace at the neurodiscal interfaceInjection should be administered under image guidance to ascertain the exact site of injectionContrast injection helps to avoid intravascular and intradural injectionInterlaminar approach may be useful in case of large herniation which impair drug delivery through the transforaminal route.[7]

Our study revealed male predominance (may be due to the peculiar dependent population in the military setting) with a mean age of 45 years for the procedure.

Among the indications, there was no significant difference between the response of diffuse disc bulge, disc protrusion, disc extrusion and postoperative patients in pain and function in the immediate post-TFEI. At 3 months and at 6 months of follow-up, there was a significant difference between the groups with diffuse disc bulge showing a persistent benefit with lowest mean rank followed by protrusion and extrusion lastly by postoperative patients. There were no patients in the sequestrated disc group.

The effect of the injection lasted till at least 6 months and was found to be equal in all the groups under 3 months of injection, after which there is variations in response in our subgroups. The overall statistically positive outcome of these injections was noted in a majority of the patients till at least 6 months. There was improvement noted in all the subgroups; maximum benefit was noted in population with disc bulge and minimum in the postoperative patient, and the results are comparable at 6 months follow-up. In a subgroup of Spine Patient Outcomes Research Trial, Radcliff et al. concluded that epidural steroid injections are associated with a surgical avoidance rate of 41%.[8]

In our study, the main side effect rarely complained by the patients was backache, although it was transient in nature. There were no intrathecal injection and good epidural spread of the contrast noted in all the patients. No cases of intravascular injection, paraplegia, headache, or blindness due to TFEI per se were reported.

The change in the disability according to the revised ODI for back pain also exhibited the same pattern as the change in VAS.

The results of our study correlated with the results of Tecer et al. in that we have demonstrated a homogenous improvement in pain scores till 6 months' follow-up.[9] The RCT published by Ghahreman et al. indicate that reduced pain score in the study population is well corroborated with reduced disability scores; similar such change is also noted in our study population.[10]

There are conflicting reports of the use of steroids in treating low backache. Ng et al. state that there is no significant difference between the outcomes in the steroid and local anesthetic combination versus local anesthetic only injection at 3-month follow-up.[11] We have used a uniform pharmacological combination of long-acting local anesthetic and steroid in all our subgroup of patients and found significant difference up to 6 months. Their study, however, concludes that there is significant improvement in patients receiving TFEI.

One of the landmark trials which include WEST trial conducted by Arden et al. state that these injections provide transient relief at 3 weeks but not later. They have further defined their definition of pain relief as >75% over the period of follow-up; which we believe is arbitrary and too high a cutoff. The selection of patients in this study was done on clinical findings alone with imaging not being considered as inclusion criteria. The co-existing other causes of back pain like facet joint arthropathy may have been overlooked thereby contributing to bias.[12]

Karppinen et al. concluded that the transforaminal injections are helpful in the management of the contained herniation and are counterproductive in non-contained herniations such as extrusion.[13] However, our study conclusively exhibits that the technique is useful in both contained as well as non-contained herniation with a relatively high success rate seen in the disc bulge subtype.

Carette et al. in their study state that over a 12-month follow-up, there is no significant change noted in the function or the need for surgery is not reduced.[14] However, in their study, the selection of patients was done using CT Scan as the initial modality for screening the population vis-a-vis our study where MRI along with a strict inclusion criteria was used as a screening tool in addition to the clinical findings; hence, the difference in the outcomes.


To conclude our the technique of fluoroscopically guided TFEI is a good minimally invasive treatment option for patients suffering from pain and disability due to discogenic pain. Our study is unique as we have used objective criteria and statistically proven good results in all cases for at least 6 months where the quality of life improves postprocedure. This study also emphasizes the use of epidural spread of contrast under fluoroscopy guidance correlates well with the success of the procedure and helps in predicting adequate instillation as well as the spread of the drug. This entity should be embedded as part of the regular algorithm of management of low backache with radiculitis as the results are encouraging.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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