OUP user menu

A Systematic Review of the Effectiveness of CT-Guided, Lumbar Transforaminal Injection of Steroids

John Bui MBBS, Nikolai Bogduk MD, PhD
DOI: http://dx.doi.org/10.1111/pme.12243 1860-1865 First published online: 1 December 2013


Objective To determine the effectiveness and safety of computerized tomography (CT) guided, lumbar transforaminal injection of steroids in the treatment of radicular pain.

Design Systematic review of published literature.

Interventions Two reviewers independently assessed 19 publications on the effectiveness and safety of CT-guided, lumbar transforaminal injection of steroids.

Outcome Measures For effectiveness, the primary outcome was the success rate for relief of pain. For safety, the radiation exposure involved and the nature of complications were determined.

Results Much of the literature fails to provide evidence. Two studies reported decreases in mean or median pain scores but no other data. Two studies reported success rates of between 34% and 62% for achieving 50% relief of pain at between 1 and 6 months after treatment. CT-guided injections may involve greater radiation exposure than does fluoroscopy-guided injections and do not avoid catastrophic spinal cord injury.

Conclusion The evidence-base for CT-guided lumbar transforaminal injection of steroids is meagre. This intervention is not more effective than fluoroscopy-guided injections and is not demonstrably safer.

  • Radicular Pain
  • Lumbar
  • Transforaminal
  • Injection
  • Steroids
  • CT
  • Computerized Tomography


Lumbar transforaminal injection of steroids is a treatment for radicular pain that requires imaging guidance. Fluoroscopy-guidance is the original, classical technique [1,2] and is favored by pain medicine specialists and by some radiologists. Computerized tomography (CT)-guidance is largely favored by radiologists.

The choice between fluoroscopy guidance and CT guidance seems to be governed by personal preference, the availability of the necessary device, and the prior training of the physician performing the procedure. Pain physicians are more likely to have access to fluoroscopy and will have been trained in that modality, whereas radiologists will have access to CT and will have trained in its use.

However, the choice between fluoroscopy and CT is not a simple matter of personal preference or equivocal differences between craft groups. Although not evident in the published literature, conflicts have arisen in medicolegal proceedings in which claims and counterclaims have been raised that CT guidance is the superior and preferred procedure. Proponents of CT guidance believe that it is effective, more accurate, and safer than fluoroscopy guidance. The present review was undertaken to determine if these beliefs are supported by the published literature.


A literature search was conducted to harvest the literature on the effectiveness, accuracy, and safety of CT-guided lumbar transforaminal injection of steroids. The PubMed database was searched using various combinations of the search terms: CT, lumbar, injection, steroids, transforaminal, perineural, radicular, effectiveness, safety, complications, and radiation. As well, the bibliographies of primary studies and reviews of the efficacy and complications of lumbar transforaminal injection of steroids were consulted.

Articles identified as potentially useful were assessed independently by the two authors: one radiologist in training and one pain medicine specialist. Their assessments were led by several questions.

With respect to CT-guided lumbar transforaminal injection of steroids:

  • Does the article provide any evidence of effectiveness?

  • Is that evidence valid and compelling?

  • If not, what are the limitations?

  • If so, how might the evidence be summarized?

  • Does the article provide any evidence on accuracy?

  • Does the article provide any evidence on safety or hazard?

  • Does the article provide any evidence on complications?

For the assessment of evidence of effectiveness, the assessors looked for an elementary set of data from each study, such as:

  • Baseline data, so that the severity of presenting complaints and the magnitudes of improvements might be gauged.

  • A follow-up period of at least 1 month, which might be the shortest acceptable period over which an outcome might be considered clinically meaningful.

  • Continuous data that indicated not only the mean or median pain scores but also their distribution, so that the distribution of outcomes might be gauged.

  • Categorical data that would indicate the success rate of the treatment.

  • Data on outcomes other than pain, which might corroborate relief of pain and might indicate the impact of treatment on the burden of illness, e.g., disability and use of health care.

Following the independent appraisal, the assessors compared their evaluations. If they disagreed, the points of disagreement were discussed until an agreement was reached. Once agreement was reached, a narrative summary of the evidence provided by the article was composed.


The literature search yielded 19 primary articles: nine on effectiveness, none on accuracy, three on safety, and seven on complications. There were no instances of pertinent disagreement between the assessors on what individual studies contributed. The assessors differed only in the severity of their criticism of studies that both assessors rejected as providing valid or useful evidence.


There were no controlled trials of the efficacy of CT-guided lumbar transforaminal injection of steroids. There was one study that compared CT-guided injections and fluoroscopy-guided injections, which thereby also provided observational data. Otherwise, there were another eight publications that reported outcomes. Conspicuously, all the studies hailed from European sources; none came from the United States or from countries of the British Commonwealth.

Five studies were rejected for failing to provide valid evidence of effectiveness on a variety of grounds (Table ). One [3] was published as a scientific exhibit rather than a research study. It claimed success rates, but successful outcomes were not defined, and numerical data were not provided. Two studies [4,5] used either CT-guided, interlaminar injections or transforaminal injections but did not stratify the outcomes for the procedure performed and therefore did not provide explicit data on the effectiveness of transforaminal injections. Another two studies [6,7] reported success rates, but baseline data were not provided, and definitions of successful outcome were either ambiguous or not provided.

View this table:
Table 1

The cardinal deficiencies of studies rejected as providing evidence of effectiveness of computerized tomography-guided lumbar transforaminal injection of steroids

Gangi et al. [3]Schmid et al. [5]Riboud et al. [4]Lutze et al. [6]Zennaro et al. [7]
Various interventions but outcomes not stratified+++
Success not defined+++
No numerical data++
No baseline data++++
Sample size not stated+

The only head-to-head comparison of CT guidance and fluoroscopy guidance occurred in one of the studies rejected because the CT-guided injections were either transforaminal or interlaminar [6]. The authors claimed that those patients “who underwent CT-guided treatment for primary discogenic nerve root irritation … had markedly better results in the overall assessment after 6 months. However, the differences in the median values among the two groups are not large enough to exclude the possibility that the difference is due to random sampling variability.” No numerical data were provided to accompany this statement. It seems to indicate that the differences observed were neither statistically nor clinically significant.

Of the four, accepted studies, one [8] treated 140 patients with radicular pain due to disc herniation using a single injection of 30–50 mg triamcinolone combined with 2–3 mL of 0.5% bupivacaine. It reported group scores, which showed a decrease in mean pain score from 7.3 before treatment to 3.9 at 1 month after treatment and 3.8 at 3 months. No standard deviations were reported. Categorical data from which to calculate success rates were not reported.

The second study [9] treated 42 patients with radicular pain due to spinal stenosis using 80-mg triamcinolone combined with 4-mL bupivacaine. It reported a statistically significant decrease in median group scores for pain from 9 before treatment to 2.5 at 6 months after treatment, but no data were reported from which success rates could be calculated.

The third study [10] treated 37 patients with radicular pain due to foraminal stenosis or disc herniation using one, two, or three injections of a mixture of 2-mg ropivacaine, 40-mg triamcinolone, and 50-mg tramadol. At 6 months after treatment, 23 (62% ± 16%) had 50% relief, with a mean pain score of 1/10.

The fourth accepted study [11] had the hallmarks of a good observational study. Outcomes were reported for various, pertinent domains, such as pain scores, percentage relief of pain, duration of relief, and subsequent use of medications, but the manner in which these outcomes were reported is confusing because various baseline features were lumped and outcomes were not stratified. Of the 160 patients treated, 139 were treated at lumbar levels; the rest were treated at cervical and thoracic levels, but outcomes for different levels were not separately reported. The patients had different causes of radicular pain, such as foraminal stenosis, disc herniation, a combination of both, or other causes, but although success rates for some of these entities were reported, outcomes for lumbar, cervical, or thoracic pathology were not distinguished. The proportions of patients achieving 50% relief of pain were reported but not stratified for segment treated or for pathology. Particularly confusing were the data on duration of relief. Although duration relief was reported, the magnitude of that relief was not reported. Although 68 patients were said to have lasting relief for the duration of follow up, the period of follow up was 14.8 ± 9.1 months, which implies that some periods were quite short. Meanwhile, a further 34 patients were said to have had only temporary relief, but for a mean duration of 3 months, the range not being specified. Reworking the data, as best as possible, suggests the following:

  • Of 49 patients with disc herniation, 24 obtained lasting relief, with 90% of these having at least 50% relief, which amounts to a success rate of 44% ± 14%.

  • Of 59 patients with foraminal stenosis, 22 had lasting relief, with 90% of these having at least 50% relief, which amounts to a success rate of 34% ± 12%.

  • Of those patients with lasting relief, only 78% also ceased medications. Thus, the success rate for relieving pain and also ceasing medications may be lower than the success rates for relieving pain alone.

Radiation Safety

One study directly compared the radiation exposure with a phantom provided by CT and by fluoroscopy [12]. It found that the radiation exposure of a standard CT protocol was 1.5–3.53 mSv depending on the number of scans used. This dose could be reduced to between 0.22 and 0.43 mSv if a low-dose protocol was used, which is in agreement with another study that assessed only the radiation exposure of standard and low-dose CT protocols [13].

For conventional fluoroscopy, the former study [12] reported an exposure of 0.43 mSv for continuous fluoroscopy and 0.07–0.16 mSv for pulsed fluoroscopy. However, in both instances, the exposure time for fluoroscopy was 1 minute, which is far in excess of the time required for executing a lumbar transforaminal injection. A separate study found that the average time for a conventional lumbar transforaminal injection using fluoroscopy was 15 seconds, with a range of 5–30 seconds [14]. Thus, allowing for 7 seconds of intermittent, pulsed fluoroscopy and up to 8 seconds of continuous fluoroscopy, a realistic estimate of radiation exposure would be 0.06 plus 0.02 mSv, for a total of 0.08 mSv. This estimate is three to five times less than that of low-dose CT protocol and 18–40 times less than a standard protocol.

Anatomical Accuracy

No published studies addressed the comparative anatomical accuracy between CT-guided and fluoroscopy-guided transforaminal injections. In the absence of empirical data, the issue of anatomical accuracy remains a matter of theory and subject to discussion.


The literature search discovered two practice audits of so-called complications [15,16], five reports for a total of eight cases of catastrophic complications [17–21], and an educational article that provided unique information [22].

Although transient side effects such as exacerbation of pain and vasovagal reactions have been described [15,16], these do not constitute complications of transforaminal injections of steroids because they do not involve lasting impairments. The only complication of lumbar transforaminal injection of steroids that has been reported is spinal cord injury.

Ostensibly, the mechanism of injury is the injection, into a radicular artery that reinforces the anterior spinal artery, of either a particulate steroid that causes an embolism [21,22] or of a steroid preparation that contains additives that are directly neurotoxic [23]. Critical for avoiding this complication is the use of a test dose of contrast medium to identify uptake into a radicular artery. If an artery is seen, the procedure can be aborted and complications avoided.

In the conduct of lumbar transforaminal injections, it appears that radicular arteries are rarely encountered, or images of their appearance are rarely published. The literature provides one image of a lumbar radicular artery captured using fluoroscopy and digital subtraction imaging [22]. No images have been published of the appearance of lumbar radicular arteries captured on CT.

The epidemiological evidence shows that CT guidance is not immune to vascular complications. Of the eight reported cases of spinal cord infarction following lumbar transforaminal injection, five followed CT-guided procedures [17–19,21].


A feature of the literature on CT-guided lumbar transforaminal injection of steroids is that authors have universally sought to convey a favorable impression of the procedure as an effective treatment for lumbar radicular pain. However, for lack of rigor, in one or more respects, that literature falls short of providing compelling evidence.

More than half of the literature is barely more than anecdotal, for it provides no explicit quantitative data. Most often authors reported the outcomes of CT-guided injections by either the intralaminar or transforaminal route but did not provide data specifically for transforaminal injections. Otherwise, studies claimed success but did not define what success entailed.

The remainder of the literature provided some data but to various, yet incomplete, extents (Table ). Two studies reported continuous, group data that implied that the treatment could be effective [8,9], but those data do not indicate how often the treatment is effective or by how much.

View this table:
Table 2

The available numerical data on the effectiveness of computerized tomography-guided transforaminal injection of steroids for lumbar radicular pain

StudyPathologyPain Scores (0–10)Success
Lee et al. [8]Disc herniation7.33.9NA
Karaemínoğullari et al. [9]Foraminal stenosis92.5NA
Wewalka et al. [10]Disc herniation or Foraminal stenosis62% ± 16%
Berger et al. [11]Disc herniation44% ± 14%
Foraminal stenosis34% ± 12%
  • NA = not available.

In that regard, not providing categorical data and success rates fails to serve the procedure or physicians wanting to adopt it. Given only the mean scores before and after treatment, physicians cannot tell how many of their patients might benefit or to what extent. For that purpose, explicit categorical data are required.

Only two studies provided such data. One reported that 62% ± 16% of patients with disc herniation or foraminal stenosis might expect 50% relief of pain [10]. The other reported that 44% ± 14% of patients with disc herniation, and 34% ± 12% of patients with foraminal stenosis could expect that degree of relief [11].

What is not evident from the literature is if this degree of relief was significantly worthwhile clinically. Only one study [11] addressed secondary outcomes. It reported that 78% of patients who experienced relief also ceased medications [11]. No studies reported other outcomes such as restoration of function, or return to work, which would corroborate the degree of relief of pain was beneficial.

The poverty of data, both in quantity and quality, expressed for CT-guided lumbar transforaminal injections stands in contrast with reasonable volume of evidence for fluoroscopy-guided injections, which includes observational studies, pragmatic controlled trials, and placebo-controlled trials [24]. For evidence of effectiveness, CT-guided injections would have to defer to the data from fluoroscopy-guided injections.

The fact that all of the literature on CT-guided injections hails from Europe is not without serious relevance for physicians in the United States. Various funding agencies in the United States are moving to require five studies, three of which must be in US samples before an intervention is deemed effective. The lack of such evidence for CT-guided injections may threaten its reimbursement.

The issue of anatomical accuracy remains vexatious. Proponents of CT guidance might argue that the advantage of their technique is that it shows soft tissues such as the target nerve. In response, proponents of fluoroscopy-guidance might respond that it is not necessary to see the nerve in order to avoid it; injury to the nerve can be avoided with careful technique that involves moving the needle slowly during its final placement. Reciprocally, proponents of fluoroscopy-guidance might argue that fluoroscopy provides a real-time, frontal view on which any radicular arteries will be evidence in their full extent, especially if digital subtraction imaging is used. Proponents of CT-guidance might respond that modern devices can rapidly acquire images beyond the plane in which the needle is placed and in which any arteries filled with contrast medium will be apparent. Pivotal to such disputes is the radiation exposure required to produce the necessary images.

The published literature on radiation safety is limited to three studies [12–14], but this literature is somewhat dated. The data provided do not necessarily accurately reflect the radiation exposure encountered using modern technology of modern protocols. Some authorities recommend digital subtraction imaging in order to identify arterial filling when performing fluoroscopy-guided transforaminal injections [2,21,22,24]. If digital subtraction imaging is used, it would add to the radiation exposure of the fluoroscopy-guided technique, which might exceed the exposure associated with CT guidance. On the other hand, modern CT scanning can rapidly produce high-resolution images in three dimensions, using multislice acquisition, but there is no literature on the total radiation exposure that such protocols are required in the conduct of lumbar transforaminal injections. There is, therefore, a vacancy for literature describing and comparing the radiation exposure of contemporary protocols of fluoroscopy-guided and CT-guided techniques.


In terms of the questions raised to prompt this review, grounds are lacking to prefer CT guidance over fluoroscopy guidance. Fluoroscopy guidance has a stronger evidence base both for effectiveness and for efficacy, and CT-guidance has not proven to be safer. Unresolved are whether modern techniques of either fluoroscopy guidance or CT guidance involve greater radiation exposure, and whether the purported accuracy of either technique justifies that radiation exposure.


View Abstract