Effect of supraneural transforaminal epidural steroid injection combined with caudal epidural steroid injection with catheter in chronic radicular pain management: Double blinded randomized controlled trial.

Introduction

Chronic lumbosacral radicular pain (CLRP) is a common condition in pain and spine centers. Treatment is challenging among patients who do not respond to either medication or physiotherapy and epidural steroid injection (ESI) is one commonly used intervention to alleviate radicular symptoms¹. These inhibit the synthesis of prostaglandins, interrupting nociceptive c fibers and reducing edema surrounding the nerve root^2–4.

Different approaches of ESI are available, namely, transforaminal ESI (TFESI), interlaminar ESI (ILESI), and caudal ESI (CESI)^5–9. The effectiveness of these three injected approaches has been shown. Related studies^10–12 have reported that TFESI was more beneficial than CESI regarding pain relief in herniated disc or radicular pain¹³. However, one recent systematic review and meta-analysis revealed TFESI could be weakly recommended over CESI¹⁴. Furthermore, one retrospective study showed adjunctive CESI on TFESI significant relieved more pain than only TFESI¹⁵. Unfortunately, a prospective study has not been conducted of the additional effects of combining the epidural steroid approach. Consequently, this study aimed to compare the effectiveness of pain relief and functional outcome between additional CESI to TFESI and TFESI separately in chronic lumbosacral radicular pain in a prospective randomized study and also to investigate possible complications during injection.

Methods

Interventions

The intervention was performed as a day surgery using local anesthesia. The treatment level determined for supraneural transforaminal approach was based on clinical symptoms correlating with MRI. All patients were placed in the prone position, then pulse oximetry and noninvasive blood pressure were monitored. The lower back and buttocks areas were cleaned using sterile fashion technique.

A C-arm fluoroscope (9900 Elite, Super C, OEC, UT, USA) was adjusted and rotated obliquely 20 to 25 ^o ipsilateral to the affected side and 0 to 10 ^o cephalo-caudad tilt until aligned with the superior vertebral end plate. The needle entry points were identified and the skin was infiltrated with 4 to 6 mL 1% lidocaine. A Quinke needle (22-G, 10 cm long) (Unilever, Japan) was inserted in the direction of the radiation beam. The supraneural transforaminal technique was performed, and the tip of the needle was placed below the pedicle and within the upper half of the intervertebral foramen in the lateral image. Then 0.5 to 1 ml of nonionic contrast media (Omipaque 300, GE Healthcare, Shanghai, China) was injected via extension tubing to confirm the needle’s location at the target area under real time fluoroscopy. The caudal epidural space was identified using fluoroscopic guidance in the lateral position and then a 16-gauge introducer Touhy needle (Epimed International RK, Epimed International, Johnstown, NY, USA) was inserted through the sacral hiatus into the caudal space and an epidural catheter was inserted using Touhy needle. Then 0.5 to 1 ml of nonionic contrast media was injected via epidural catheter (Epimed International RK, Epimed International, Johnstown, NY, USA) under real time imaging to confirm the desirable vertebral level and covered target site on both groups as shown in Figure 1 and Figure 2. T-group underwent 0.08% Levobupivacaine (Abbvie S.r.l., Italy) plus 40 mg of triamcinolone (L.B.S. Laboratory Ltd., Bangkok, Thailand) in a total volume of 3 ml via only the intervertebral foramen. Those in the TC group underwent 3 ml of 0.08% Levobupivacaine plus 40 mg of triamcinolone using the transforaminal approach combined with 10 ml of 0.025% Levobupivacaine plus 40 mg of triamcinolone via caudal epidural catheter.

Figure 1. An anteroposterior view of contrast flow in combined supraneural transforaminal and caudal with catheter injection.

Figure 2. An lateral view of contrast flow in combined supraneural transforaminal and caudal with catheter injection.

Results

In total, 54 eligible patients were enrolled and allocated in equal groups of 27. Two participants were more excluded due to wrong allocation from progressive weakness and scheduled for surgery in the T group. Consequently, 25 patients remained in the T group and 27 in the TC group as shown in Figure 3. No differences were found regarding demographic data, sex, weight, clinical diagnosis, level of pain dermatome, preprocedural VNRS and ODI before intervention as presented in Table 1¹⁸. Mean baseline VNRS was high in both groups; 74.8 ± 16.8 and 69.6 ± 15.1 in the T and TC groups, respectively.

Figure 3. Flow diagram of enrolled patients.

Overall, average VNRS was significantly reduced from baseline after receiving the procedure at 1, 3 and 6 months in both groups (P-value <0.05). However, the study showed significant differences between group comparisons at 1 and 3 months (P-value=0.009 and 0.044), respectively) as shown in Figure 4¹⁸. Moreover, average ODI was significantly improved from baseline at 1, 3 and 6 months in both groups. Nonetheless, no significant difference was found in average ODI over the study period between group comparisons (p=0.235) as presented in Figure 5¹⁸.

Figure 4. Average verbal numerical rating scale: between-group comparison (Line graph is presented with mean and 95%CI error bars) T group = transforaminal, TC group = transforaminal and caudal.

Figure 5. Average Oswestry Low Back Pain Disability Index: between-group comparison (Line graph is presented with mean and 95%CI error bars) T group = transforaminal, TC group = transforaminal and caudal.

Discussion

This constituted the first prospective study to compare clinical outcomes of combined CESI to TFESI (TC group) and TFESI alone (T group) to alleviate chronic lumbar radicular pain.

This study showed combined CESI with TFESI provided more effective pain relief than TFESI separately at 3 months. Moreover, a trend was shown for higher pain relief in the TC group among spondylolisthesis patients ( total of patients in the TC group compared with 3 of 7 patients in the T group) and fail back surgery syndrome (5 of 6 patients in the TC group compared with 1 of 5 the patients in the T group) at 3 months in subgroup allocation, without significant difference in which prior studies reported the mechanism of radicular pain in spondylolisthesis was usually from mechanical compression resulting in inflammatory changes in the enclosing nerve root and venous and arterial flow disability^19,20. Accessing the epidural space of the supraneural TFESI is relatively difficult in a severely degenerated and narrowed foramen^13,21. Furthermore, the injected volume of lumbar TFESI is likely to influence the results. Prior studies have reported that larger injected epidural volumes provide effective pain relief^16,22 and a larger injected volume can lavage waste products from the epidural space, reducing the abnormal signal of the offending nerve and increasing blood flow to the ischemic nerve²³. Desai et al.²⁴ confirmed that the more vertebrae covered by the injected volume the better the outcome, and Furman et al.²⁵ commented that a larger injected volume was needed for failed back surgery patients. Unsurprisingly, the TC group showed trending toward more pain relief in spondylolisthesis and failed back surgery syndrome.

Unfortunately, this study showed the TC group experienced more significant pain relief than the T group alone at 3 months this might have been from the effect of combined techniques peaking at 3 month, then it might have gradually worn off from steroid’s action, instability and the return of softened epidural adhesion and fibrosis^15,22

However, Friedly JL et al.²⁶ found epidural steroid injection plus lidocaine proposed insignificant benefit as compare with lidocaine separately in 400 patients who had lumbar central spinal stenosis and moderate to severe leg pain. On the other hand, they demonstrated interlaminar or transforaminal approaches which were not exactly same techniques as this study.

Recently, a retrospective study reported combined caudal and TFESI in herniated disc provided more significant pain relief and improved patient satisfaction than only TFESI at 1 year¹⁵. In contrast, this study showed no significant pain relief between the 2 groups from herniated disc in subgroup allocation, for which demographic data of our patients with herniated disc showed lower average ages (mean age 37 ± 8.5 and 35 ± 5.4 in the T and TC groups, respectively) than a related study (mean age 62.4 ± 15.5 and 57.6 ± 15.7 in the T and TC group, respectively) in which younger patients might have received greater benefit from steroid injection in accordance with Park et al.²⁷ showing younger age produced a better response from TFESI. However, no significant difference was observed. Moreover, this study investigated just mild degree herniated disc such as mild unilateral paracentral disc herniation or mild foraminal stenosis and mild degree of spinal stenosis in which only the TFESI technique was sufficient to alleviate pain. Furthurmore, this study injected a larger volume in the T group (3.0 ml) compared with 1.5 ml in the study of TFESI by Kircelli A et al.¹⁵ in which a larger injected volume could cover more pain generators across multiple levels of the spine in accordance with Furman et al.^25,28,29

In addition, this study postulated that synergistic anti-inflammatory effect from the double dose of steroid in the TC group may have conferred better pain relief. However, one related study reported 40 mg was as effective as 80 mg of methylprednisolone in TFESI for lumbar radicular pain²⁹, while Kang et al.³⁰ revealed no significant difference between 10, 20 and 40 mg of triamcinolone at 1 week in TFESI for disc herniation with lumbosacral radicular pain. Unsurprisingly, this study also showed no significant difference in herniated disc concerning different dosages of corticosteroid between the 2 subgroups analysis.

Our study had several limitations. Firstly, we demonstrated radicular pain from symptomatology and physical examination, for which the source of pain may have overlapped the pain referred pattern from the zygophysial joint, sacroiliac joint pain or enclosing soft tissues^31–33, which might have limited the efficacy of the procedure. However, many common problems are involved in chronic low back pain. Secondly, electrodiagnosis was not performed in this study. Nonetheless, electrodiagnosis may have demonstrated false-negative findings, as demonstrated in a similar publication which showed 40 to 85% sensitivity depending on the referral range^34,35. Thirdly, the study did not verify anterior or posterior epidural space of contrast flow which might have affected the efficacy of the result. Fourthly, this study included a small sample size for subgroup allocation which likely underpower analysis and might not have been able to detect differences between subgroups. A larger sample size in each etiology should be demonstrated in further study. Fifthly, this study provided two different approaches, which could be increase costs of procedures. Therefore, the higher volumes should be considerated if the effective result was occurred from higher volumes. Sixthly, some patients had bilateral radicular pain but only one side that more severe pain were provided in T group which might have effected for the result. Seventhly, this study did not collect exactly the duration of pain that can have huge effect on outcome as Bicket et al.³⁶ ‘s propose. However, this study included only patients who had history of lumbosacral radicular pain more than 6 months. Lastly, we did not determine whether combination effect of oral medication, physiotherapy and placebo effect which might be effect for the result.

Conclusion

The additional effect of CESI to TFESI was more effective than TFESI separately at 3 months with no neurological deficit.

Data availability