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Steroid injections into the opening where nerves exit the spine (transforaminal injections) are slightly more effective than local anaesthetic or a salt solution (saline) injection at reducing pain for adults with sciatica.

This study found that all three techniques reduced pain for three months by over three points on a 0 to 10 point scale. It is unclear what effect they have on disability at three months or need for spinal surgery at 12 months.

There are other options which may be used when conservative treatment with physiotherapy and medication has failed or if the pain is severe. These include a midline injection of steroid and local anaesthetic into the epidural layer. This review did not find trials which compared all of these options with one another which limits the ability to decide which approach is best and any immediate implications for practice.

Why was this study needed?

Nearly 10% of the UK population have had sciatica, usually associated with low back pain.  Over 50% of people with this type of pain report a decrease in their daily activities and ability to work.

Despite the use of oral pharmacological treatments, 25% of people continue to have severe pain. Surgery is eventually required in 14% of cases, especially if the pain is accompanied by neurological problems.

A transforaminal epidural steroid injection is an option that is sometimes used to relieve radiating lower limb pain and to avoid surgery. This study aimed to compare these transforaminal steroid injections with local anaesthetic injections, saline injections and conservative options such as medication and physiotherapy.

What did this study do?

This was a systematic review and meta-analysis which included eight randomised controlled trials of 771 adults with pain radiating to the limbs. The review included trials where sciatica was moderate to severe, with or without associated low back pain and with disc abnormality confirmed on imaging.

Trials compared transforaminal epidural steroid injections given under X-ray guidance with other pain management interventions. There was variation in the number and frequency of injections, steroid type and dose per injection which limits the reliability of the combined results.

Pain was assessed using a numerical rating scale ranging from 0 (no pain) to 10 (worst possible pain). Adverse events were poorly reported in the trials, and half of them were at high or unclear risk of bias, mostly due to incomplete outcome data.

What did it find?

  • Transforaminal epidural steroid injections improved pain score from an average of 7.3 to 3.6 after one to three months. Results were similar after local anaesthetic injection or saline injection, 7.7 to 4.6. The difference between them was a clinically modest reduction in average pain score of -0.97 points (95% confidence interval [CI] -1.42 to -0.51). Analysis of three trials that used higher steroid doses showed further reduction in pain by approximately 2 points, which may indicate a dose-response effect.
  • There was no difference in physical disability scores at one to three months between the transforaminal epidural injections of steroid and local anaesthetic or saline (difference -0.89 points on the Oswestry Disability Index scale of 0 to 100, 95% CI -2.60 to 0.81).
  • There was no difference in need for surgery 12 months following the transforaminal epidural injections compared to local anaesthetic or saline injections (relative risk 0.88, 95% CI 0.55 to 1.41).
  • No trial was identified that compared transforaminal epidural steroid injections with medication or physiotherapy.

What does current guidance say on this issue?

The NHS England nerve root pain care pathway recommends conservative treatments such as medication and physiotherapy prior to invasive techniques depending on severity. Invasive techniques recommended include transforaminal epidural injection with steroid, anaesthetic or a combination of both or other techniques such as an interlaminal approach. Fluoroscopy X-rays are indicated to guide the injections in order to increase accuracy of delivery and reduce risk of nerve damage. Surgery and specialist pain services may be required.

What are the implications?

Guided transforaminal epidural steroid injections, local anaesthetic and saline injections improved pain but it is not clear if they had any effect on disability or the need for surgery as baseline values were not provided.

As none of the trials compared transforaminal epidural steroid injections to alternatives, such as physiotherapy, the review does not aid the decision on which intervention to use. It is also unclear if particular patient groups are most likely to benefit.

More information is needed about longer-term effectiveness as well as ideal steroid dosages, number of injections and how often they should be delivered in order to guide practice. Adverse events were poorly reported in the trials and further safety information is needed particularly on infection, myopathy (muscle weakness) and nerve injury as these have been anecdotally reported after the use of some steroid transforaminal epidural injections.


Citation and Funding

Bhatia A, Flamer D, Shah PS, Cohen SP. Transforaminal Epidural Steroid Injections for Treating Lumbosacral Radicular Pain from Herniated Intervertebral Discs: A Systematic Review and Meta-Analysis. Anesth Analg. 2016;122(3):857-70.

This project was funded by various departments at the University of Toronto and other Canadian hospitals.



NICE. Low back pain in adults: early management. CG88. London. National Institute of Health and Care Excellence; 2009.

Staal JB, de Bie R, de Vet HCW et al. Injection therapy for subacute and chronic low-back pain. Cochrane Database Syst Rev. 2008;(3):CD001824.

NHS England. National Pathway of Care for Low Back and Radicular Pain. London: NHS England; 2014.

Lee j, Gupta S, Price C et al. Low back and radicular pain: a pathway for care developed by the British Pain Society. Br J Anaesth. 2013;111(1):112-20.

American Academy of Pain Medicine (AAPM). Transforaminal vs. Interlaminar epidural steroid injections: Both offered similar pain relief, function for radiating low-back pain. ScienceDaily. 2014.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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Sciatica is a type of pain that radiates into the leg caused by irritation of a lumbar spinal nerve root. This may be caused by direct pressure from a damaged disc or by narrowing of the spaces between the vertebral bones. Although the problem is in the spine, the pain is felt in the area of leg that the nerve supplies.

The epidural space is a layer of fat inside the bones and ligaments of the spine. Through this layer run the nerves between the spinal cord and the rest of the body

Transforaminal epidural is an injection into the epidural space through an opening at the side of the spine where a nerve root exits.

Midline epidural is an injection into the epidural space, going through the space between the bones at the back of the vertebrae.

In this study pain of moderate to severe intensity was considered 4 or more out of 10 on a numerical rating scale.

Physical disability was assessed using Oswestry Disability Index (ODI; score range 0 to 100) with 0 indicating no disability and higher scores indicating increasing disability.


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