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Lumbar Radiculopathy: Treatment with Selective Lumbar Nerve Blocks—Comparison of Effectiveness of Triamcinolone and Betamethasone Injectable Suspensions¹

¹ From the Department of Radiology, Division of Musculoskeletal Imaging, University of Wisconsin Medical School, Clinical Science Center-E3/311, 600 Highland Ave, Madison, WI 53792-3252 (D.G.B., A.A.D.S.); Charlottesville Radiology Ltd, Charlottesville, Va (J.D.S.); and Departments of Statistics and Biostatistics and Informatics, University of Wisconsin, Madison, Wis (J.P.F.). Received August 11, 2004; revision requested October 27; revision received November 22; accepted December 27. Address correspondence to D.G.B. (e-mail: dg.blankenbaker{at}hosp.wisc.edu).

	ABSTRACT

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PURPOSE: To retrospectively determine if there is a difference in the effectiveness of triamcinolone acetonide injectable suspension versus betamethasone sodium phosphate and betamethasone acetate injectable suspension in the treatment of radiculopathy and low back pain with selective lumbar nerve blocks.

MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and was HIPAA compliant; informed consent was not required. Charts and self-reported pain score evaluations were retrospectively reviewed in 114 patients (56 men, 58 women; age range, 36–84 years; mean age, 60 years) treated for radiculopathy from 1997 to 2003 with 130 selective lumbar nerve blocks with triamcinolone or betamethasone. Perineural location was confirmed with fluoroscopic guidance. Forty-nine patients received a mixture of 1 mL of the triamcinolone, 40 mg/mL, and 1 mL of 0.5% bupivacaine hydrochloride. Eighty-one patients received a mixture of 1 mL of the betamethasone, 6 mg/mL, and 1 mL of 0.5% bupivacaine hydrochloride. Patients completed standardized pain evaluation sheets and compared their pain with baseline levels during 14 days after injection. Fisher exact test was used for data analysis.

RESULTS: From day 0 to 1 after the procedure, there was no statistically significant difference in improvement in low back pain and lower extremity pain between groups. On day 3, 42% of triamcinolone recipients and 58% of betamethasone recipients demonstrated improvement in low back pain (P = .04, Fisher exact test), whereas 55% of triamcinolone recipients and 57% of betamethasone recipients had lower extremity pain improvement (P = .33). On day 7, 45% of triamcinolone recipients and 58% of betamethasone recipients had improvement in low back pain (P = .38), whereas 52% of triamcinolone recipients and 57% of betamethasone recipients had improvement in lower extremity pain (P = .69). On day 14, 42% of triamcinolone recipients and 53% of betamethasone recipients had improvement in low back pain (P = .26), whereas 49% of triamcinolone recipients and 55% of betamethasone recipients had improvement in lower extremity pain (P = .69).

CONCLUSION: Selective nerve root blocks with betamethasone and triamcinolone reduced low back pain and lower extremity pain, although there was no significant difference in effectiveness between the two.

© RSNA, 2005

	INTRODUCTION

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Low back pain and radiculopathy are common conditions that debilitate millions of people annually (1). Current treatment for patients with low back pain and radiculopathy usually begins with conservative measures, such as exercise, weight loss, and physical therapy. When conservative measures fail or when the pain markedly limits daily activities, epidural injections or nerve root blocks with corticosteroids often are the next step in management of these patients. Epidural corticosteroids have been used to treat low back pain and radicular pain for the past century (2).

The purpose of a selective lumbar nerve block is to assist in both the identification of the involved nerve root and the palliation of the patient's pain. While corticosteroids do not cure the underlying cause of the patient's pain, they often reduce or eliminate the pain temporarily, allowing other rehabilitative efforts to proceed and a return to a normal lifestyle.

Epidural and nerve block corticosteroid injections are of value in the treatment of radiculopathy because they reduce edema and inflammation (3). Degenerated and herniated intervertebral disk material releases inflammatory enzymes such as phospholipase A2. The release of these enzymes results in edema and inflammation, which are thought to cause pain through irritation and compression of the nerve roots (4–7).

In our practice, referring physicians request a selective nerve block instead of epidural injections when there is a painful radiculopathy of a single nerve root. Two commonly used medications used for nerve blocks are triamcinolone acetonide and betamethasone sodium phosphate and betamethasone acetate preparations. Results in a previous study showed a definite advantage of the triamcinolone preparation when compared with the betamethasone preparation in epidural steroid injections (8). The purpose of our study was to retrospectively determine whether there is a difference in the effectiveness of the triamcinolone preparation versus the betamethasone preparation in the treatment of radiculopathy and low back pain with selective lumbar nerve blocks.

	MATERIALS AND METHODS

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This retrospective study was approved by our internal review board. Our internal review board did not require informed consent for retrospective review of patient records or images. Our study complied with the Health Insurance Portability and Accountability Act.

Study Population
Three of the authors (D.G.B., J.D.S., A.A.D.S.) reviewed charts and self-reported pain score evaluations of 114 patients (56 men, 58 women; age range, 36–84 years; mean age, 60 years) who received either 1 mL of triamcinolone acetonide injectable suspension, 40 mg/mL (Kenalog-40; Bristol-Myers Squibb, Princeton, NJ) or 1 mL of 3 mg betamethasone sodium phosphate and 3 mg betamethasone acetate per milliliter of injectable suspension (Celestone Soluspan; Schering, Kenilworth, NJ) as a selective lumbar nerve block for the treatment of radiculopathy from 1997 to 2003. These 114 patients represented the approximately 15% (130 of 891) of patients who returned the standard pain score sheets. Our referral base included patients seen in the orthopedic, spine, pain, rehabilitation, internal medicine, and family practice clinics. There was no change in this referral base during the time of this study. The triamcinolone preparation was used for the initial 2 years, and the betamethasone preparation was used during the next 3 years. Both medications were used in the final year. This variability in medication use was determined by the availability of each corticosteroid preparation from the hospital pharmacy.

During the study period, 130 nerve blocks were performed in 114 patients. One hundred patients received single injections, whereas 14 patients received a total of 30 injections. Of the 14 who received multiple injections, four patients received both the triamcinolone preparation and the betamethasone preparation on different occasions. Each injection was interpreted as a single occurrence. The time between the multiple injections varied and ranged from 1 to 19 months (mean, 6.0 months; median, 3.5 months). There were two study groups, one with 81 injections with the betamethasone preparation and one with 49 injections with the triamcinolone preparation.

Injection Technique
There are many publications in which the technique for performing a selective lumbar nerve block is described, but they are similar in their key elements (9–13). Although six radiologists (including A.A.D.S. and five others) were involved in performing these procedures, all selective nerve blocks in this study were performed by using a previously described technique (13). Since the procedures were performed from 1997 to 2003, experience varied over time, with increasing experience over the years. Each of the six radiologists had at least 3 months of experience when the first procedure was performed for any of the patients in this study. Standard technique was used and documented. A 22-gauge spinal needle that was 3 inches (8.9 cm) or 6 inches (15 cm) long was advanced with fluoroscopic guidance to a position just lateral to the anterior and inferior margin of the neural foramen. When the needle reached the expected location of the nerve sheath or the patient experienced radicular pain, correct position was confirmed by injection of contrast material outlining the selected nerve. The medication was injected with fluoroscopic guidance to confirm washout of the contrast material from the area around the nerve. Each patient received an injection of a mixture of 1 mL of either the triamcinolone preparation or the betamethasone preparation and 1 mL of 0.5% bupivacaine (Abbott Laboratories, North Chicago, Ill), 150 mg/30 mL.

Pain Evaluation
For 6 years, our policy was for patients to keep a record of their low back pain and lower extremity pain after the procedure. We used the term "lower extremity" to include the buttock, thigh, and lower part of the leg. The patients either mailed the forms to us or returned them at their follow-up clinical appointment. These forms were used for this retrospective study. Prior to the procedure, the patients ranked their initial pain by using an 11-point scale, with 0 representing no pain and 10 representing the worst pain. They were then asked to select postprocedural pain levels from a list of the following: worse pain, same pain, little better pain, much better pain, and no pain. These levels were determined at the following intervals: (a) the evening of the procedure, (b) 1 day after the procedure, (c) 3 days after the procedure, (d) 7 days after the procedure, and (e) 14 days after the procedure. After 14 days, patients were also asked to categorize the amount of pain medication needed as increased, decreased, or as the same.

Statistical Analysis
The Fisher exact test was used for our data analysis to determine whether there was a difference in low back pain and lower extremity pain after injection of the triamcinolone preparation versus that of the betamethasone preparation. Software (SPLUS, version 3.4, 1996; Mathsoft, Rahway, NJ) was used for this analysis. A difference with a P value of less than .05 was statistically significant. A post hoc power analysis was performed with the data.

	RESULTS

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The mean scores for low back pain and lower extremity pain were nearly identical, and the difference in the scores between the patients who received the triamcinolone preparation and those who received the betamethasone preparation was not statistically significant (Table 1).

Twenty-seven percent (19 of 71) of patients who received the betamethasone preparation and 36% (14 of 39) of patients who received the triamcinolone preparation indicated that less pain medication was needed after the procedure than was needed before the procedure. (The denominators vary, as many patients did not answer the question on the survey sheet or had an increase in or no change in pain medication usage.) These differences, however, also were not statistically significant (P = .52).

By using the results of the current study, we performed a post hoc power analysis to determine sample sizes necessary to detect observed differences in rates for response to treatment with 80% power and a P value of .05 with the Fisher exact test. For an improvement of 40% with the triamcinolone preparation and that of 60% with the betamethasone preparation (improvements that were similar to those at day 3 for low back pain), 98 patients were needed for each treatment. For an improvement of 45% with the triamcinolone preparation and that of 55% with the betamethasone preparation (improvements that were similar to those at day 7 and day 14 for low back pain), 392 patients were needed for the betamethasone preparation and 392 patients were needed for the triamcinolone preparation, with a total of 784 patients.

	DISCUSSION

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Many corticosteroids are routinely used for epidural injections and lumbar nerve blocks. There is concern, however, in regard to the use of corticosteroids containing polyethylene glycol, which is a component of some depot preparations, as this may cause neurotoxicity (14). One group has recommended that either the betamethasone preparation or the triamcinolone preparation be used for spinal injections, since these preparations do not contain polyethylene glycol (1). At our institution, we routinely used either the betamethasone preparation or the triamcinolone preparation for our epidural injections and selective lumbar nerve blocks. Our choice of medication for a particular patient was often dictated by which corticosteroid was available to our hospital pharmacy from the manufacturers. This variation in corticosteroid usage allowed us to perform this retrospective comparison.

Betamethasone and triamcinolone preparations both are categorized as salts. Triamcinolone, however, is less water soluble and more difficult to dissolve in solution than is betamethasone. In fact, several spinal surgeons at our institution have indicated that they found crystals in the epidural space at surgery in patients who had had recent epidural injections of the triamcinolone preparation. The reduced solubility of the triamcinolone preparation was proposed as a reason why it was more effective than the betamethasone preparation in the reduction of pain after epidural injections (8).

We used the betamethasone preparation as an alternative to the triamcinolone preparation for selective lumbar nerve blocks because it did not contain polyethylene glycol and because it contains both betamethasone sodium phosphate and betamethasone acetate. Betamethasone sodium phosphate is more soluble and thus provides an immediate effect, whereas betamethasone acetate is reported to be less water soluble and is thought to have a depot effect (15).

Because researchers in a recent study (8) reported that epidural injections with the triamcinolone preparation were more effective in the improvement of low back pain than were epidural injections with the betamethasone preparation, we undertook this study to determine whether our results would support those of the previous study. In contrast to the results in the prior study, we found no statistically significant difference between the triamcinolone preparation and the betamethasone preparation when used for selective lumbar nerve blocks.

We do not know why our results differ from those in the prior study by Stanczak and colleagues (8). Perhaps the more selective nature of a nerve injection makes a depot effect less important. During a selective nerve block, the needle is placed in a perineural location, typically at the site of the patient's symptoms. It may be that placement of a small volume of medication adjacent to the painful nerve will improve low back pain and lower extremity pain regardless of the type of corticosteroid used because of the local high concentration of the corticosteroid. In contrast, a depot effect with diffusion of the medication may be needed in epidural injections in patients with multilevel degenerative disease. Another consideration would be that our patients who underwent a selective nerve block may have had pain caused by different types of disease than that which was present in the patients who received an epidural steroid injection in the prior study.

It is curious that, for all times, a greater percentage of patients who received the betamethasone preparation than those who received the triamcinolone preparation had pain relief, and yet a greater percentage of patients who received the triamcinolone preparation needed less pain medication. This apparent but not statistically significant difference in the two measures of pain relief may have been caused by a statistical variation around a mean of no true difference in effectiveness. The apparent trend in less use of pain medication with the triamcinolone preparation, however, could reflect factors other than pain alone.

Our study had limitations, which included sample size in our 6-year retrospective review. The treatment differences at late times, 7 and 14 days after the procedure, did not achieve statistical significance. The absence of statistical significance may have been caused by a true lack of difference or by our inability to detect small differences because of an insufficient sample size, or by both. As noted in our post hoc power analysis, a study with a much larger patient population might confirm the statistical significance of the apparent improved response with the betamethasone preparation.

A second limitation of our study was that it included patients who received multiple injections and even a few who received each of the corticosteroid preparations but at different times. Although we know of no reported data, anecdotal reports indicate that patients can have better improvement in their pain with repeated injections. There were, however, only a few patients in this category. Because of the small number in this crossover group, this factor should not have had a substantial effect on the basic conclusion we determined from our analysis.

A third limitation of our study was that it did not take into account duration of pain prior to the procedure or multilevel disease. This information was not available in our retrospective study. Further evaluation of the duration of pain before the procedure or of the presence of multilevel disease would require a randomized study.

Finally, the pain scale that was used during the time of this study was not consistent. Although patients were initially asked to grade their pain on a scale of 0 to 10, their subsequent responses were limited to a five-point scale. We learned from those who set up the original pain scale that they had chosen the five-point scale because it was simpler for the patient to use. To provide a more consistent pain response in our clinical practice, we recently changed our pain scale from the five-point scale to the scale of 0 to 10 at all intervals.

In conclusion, we found no significant difference in the effectiveness of the triamcinolone preparation and of the betamethasone preparation for reduction of low back pain or lower extremity pain when used in a selective lumbar nerve block. On the basis of the results of this study, we have begun using the triamcinolone preparation for selective nerve blocks, as this preparation is available at a lower cost from our hospital pharmacy.

	FOOTNOTES

 
Authors stated no financial relationship to disclose.

Author contributions: Guarantors of integrity of entire study, D.G.B., A.A.D.S.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, D.G.B., J.D.S.; clinical studies, D.G.B., A.A.D.S.; statistical analysis, J.P.F.; and manuscript editing, all authors

	References

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