The Long-Term Efficacy of Radiofrequency Ablation With and Without Steroid Injection

Abstract

Background

Radiofrequency ablation (RFA) has been proven to be an effective option for treating chronic low back pain. In addition to RFA as a treatment modality, the administration of concomitantly to minimize the effect of hyperalgesia is common practice. However, there is insufficient evidence about the long-term outcomes of their use.

Methods

This was a retrospective study that examined 239 patients who received spine, knee joint, and sacroiliac joint RFA between June 2014 and June 2018. Pre- and post-procedure pain scores, percent improvements, and duration of relief were included in our review.

Subjects

This study included 239 patients of which 191 patients received steroids with their RFA.

Results

These 191 patients experienced an average improvement of 48.48% relief for an average of 137.52 days. Forty-eight patients did not receive steroids with RFA and had an average improvement of 46.36% for an average of 126.10 days. The statistical analysis revealed there was no significant difference between the two groups for percent improvement (p = 0.71) and duration of relief (p = 0.67).

Conclusions

Patients who received steroids with RFA compared to RFA alone did not differ significantly in percent improvement in pain and duration of relief.

Introduction

Radiofrequency ablation (RFA) has been proven to be an effective option for patients with chronic low back pain. In 1994, North et al. conducted the first study of radiofrequency denervation in patients who reported at least a 50% pain reduction following diagnostic medial branch posterior primary ramus blocks. Among the 42 patients in the study, 45% reported at least 50% relief of pain for their long-term follow up.¹ Several years later, Dreyfuss et al. selected a group of 15 patients who responded well to diagnostic medial branch blocks of the zygapophysial joints. These patients subsequently underwent lumbar medial branch neurotomy. At the 12-month follow up, 60% of participants continued to have at least 90% of pain relief and 87% of participants had at least 60% pain relief.² These studies, among many others, established the efficacy and safety of RFA as a treatment modality for chronic pain.

Often pursued as a modality for those who have failed more conservative therapies, RFA is a relatively safe procedure with few side effects. Common complaints with RFA and other similar procedures are localized pain, tenderness, or soreness over the needle insertion area. This transient discomfort has been postulated to be related to the thermal lesion around the target site and trauma from electrode insertion that results in a local inflammatory response.³

Pro-inflammatory cytokines released because of injury promote and intensify the process of nociception.⁴ This observation has led to our practice of administering steroids to inhibit or decrease the effect of pro-inflammatory cytokines on the body. Studies of pentoxifylline and its inhibitory effect on the development of hyperalgesia in rats have shown enhanced IL-10 levels which promote anti-inflammatory responses and decreased the production of pro-inflammatory cytokines including TNF-alpha, IL-1beta, IL-6, and NF-kappaB.⁵ The anti-hyperalgesic effects of pentoxifylline have been attributed to the modulation of these pro-inflammatory cytokine levels. Wordliczek et al. noted the effect of administering pentoxifylline prior to any type of injury in animals and patients. In these experimental and clinical studies, the steroid was associated with a decrease in TNF-alpha levels in animals and demonstrated an inhibition of pain-related behavior. Similarly, patients who received pentoxifylline intravenously prior to elective cholecystectomy ultimately had lower doses of opioid consumption compared to their control counterparts.⁴

These studies, among others, have led to the practice of routine usage of steroids in pain procedures in hopes of producing better outcomes. While the benefits of steroids in minimizing the development of hyperalgesia are known within the pain community, there is insufficient evidence about the long-term outcomes of their use. In this review, we analyzed studies on the concurrent use of steroids with radiofrequency ablation. Dobrogowski et al. noted a short-term benefit of using pentoxifylline or methylprednisolone immediately following RFA, however there did not appear to be any long-term benefits. This paper examines the same question with a significantly greater number of cases.

Methods

Following IRB exemption, a retrospective chart review examined the data of patients who received RFA of the spine, knee joint, and sacroiliac joint between June 2014 and June 2018. Demographic data, pre-procedure pain scores, post-procedure pain scores, percent improvement (a composite outcome of improvement in pain and function), duration of improvement, and whether the patient received steroids during the RFA procedure were recorded.

Data was collected from the electronic medical record and was then entered into an excel sheet. Statistical analysis was performed using SPSS version 22 (IBM). An analysis was performed to determine whether the true means of the pre- and post-procedure pain scores, percent improvements, and duration of relief differed significantly between patients receiving steroids with their procedure and those who did not.

Results

This study included 239 patients. The majority of patients (n = 191) received steroids with their RFA. These patients experienced an average improvement of 48.48% relief for an average of 137.52 days. Those not receiving steroids with RFA (n = 48), had an average improvement of 46.36% for an average of 126.10 days. There was no statistically significant difference between both groups regarding age, sex and site of RFA performed. Statistical analysis revealed that there was no significant difference between those receiving steroids and those that did not in the areas of percent improvement (p = 0.71) and duration of relief (p = 0.67).

Discussion

This study made use of readily available data to answer a question that has been assumed to be answered but in reality, hasn’t been studied in great detail. Steroids are given during an RFA procedure to reduce the amount of inflammation present at the site of the procedure. Inflammation has been observed in nerves at the site of RFA with the levels of many pro-inflammatory cytokines being elevated in and around these nerves.⁶ It is this fact that has predicated the use of steroids in RFA in the eyes of many without further study of the actual effects of the drugs. Many advocate for the use of corticosteroids during the procedure to reduce the immediate flare of pain associated with RFA.⁷ In this regard, there is a study demonstrating the effects of corticosteroids in this capacity, but this same study has also shown steroids with RFA to have no long-term effects on outcomes.³

The study presented here examines this same question. The medical records of all patients undergoing RFA at a major academic medical center in the US were analyzed. Of those, it was found that 239 patients were successful in getting RFA with191 receiving steroids and the other 48 did not (Table 1). When the clinical outcomes of these two patient groups were compared, the results were clear. The steroid group did not significantly differ from the non-steroid group in any long-term outcome collected.

Table 1. Comparison of Patients Who Received RFA With and Without Steroids.

		Number of Cases		Mean Pre-Procedure Pain Score		Mean Post-Procedure Pain Score		Mean Percent Improvement		Mean Duration of Relief
With Steroids		191		6.62 ± 1.87		3.52 ± 2.65		48.48 ± 34.90		137.52 ± 169.35
Without Steroids		48		6.88 ± 1.17		3.71 ± 2.74		46.36 ± 37.42		126.10 ± 133.91
		Total = 239		P = 0.36		P = 0.65		P = 0.71		P = 0.67

As mentioned previously, the short-term benefits of steroids with radiofrequency ablation are established, but the long-term outcomes have not been studied in great detail. A study by Roy et al. consisted of 34 patients with chronic paravertebral low back pain who underwent RFA followed by a 20mg injection of methylprednisolone acetate. Following their patients as far as 12 months post-procedure, they found significant long-term improvement in pain and disability. They note the beneficial effects of RFA were not apparent in the initial few weeks, but the effects were noticeable much earlier when it was combined with the steroid injections.⁸ It is unclear whether the methylprednisolone had any long-term effects because dedicated groups to receive only the RFA, only the steroid, or a placebo were not part of the study.

In contrast, Kaustuv et al. investigated the independent effects of RFA or steroid injection on sacroiliac joint pain. Their study included 30 patients with sacroiliac joint pathology. Fifteen patients received pulsed radiofrequency denervation (PRF) and the remaining 15 received intraarticular depot methylprednisolone. Over a 6 month follow up period, they found significant reductions in pain scores for both groups, which was defined as greater than or equal to 50% pain relief and functional improvement. At 1-, 3-, and 6-months post procedure, the PRF group had 100%, 86.7%, and 86.7% of patients with significant pain reduction. In contrast, the steroid group only had 20% of their patients with greater than or equal to 50% pain reduction at 3- and 6-months post-procedure.⁹ This study supports the finding of short-term pain reduction with steroids, but not necessarily long-term reductions. Even though 20% of their patients continued to have significant improvement in pain relief, it is considerably less compared to the RFA group and 12-month follow up data was not reported.

While both of these studies lay the foundation to ask the question of whether steroids are beneficial in the RFA procedure, neither answers this question. This necessitates the work done in the study presented here. Our study set out to answer this question and was able to provide a preliminary conclusion.

A recent study showed that also the use of steroids following RFA does not reduce neuritis after procedure.¹¹ So it seems that injecting steorids after RFA does not provide short or long term benefit. There are patient with uncontrolled diabetes and all other kind of morbidities that may experience harm from using steroids. So it is time to question this practice.

Limitations

This was a retrospective study that could not adjust for all confounders as opioid use after RFA.

Conclusions

This study reaffirms results collected in previous studies; corticosteroids do not improve long-term outcomes for patients receiving RFA. There is no significant benefit to their use in the RFA procedure. RFA itself has been demonstrated on many occasions to be an effective procedure to treat chronic pain when other treatment modalities have failed.¹⁰ This procedure can and should be continually refined to continue getting better results for patients. While this study does provide insight, it does not provide decisive answers to these questions. The retrospective nature of this study limits the generalizability and broader conclusion that can be drawn from our results. Further work remains to probe the clinical role that corticosteroids may play in improving the short-term outcomes for these patients. Larger, randomized, controlled trials need to be undertaken to find decisive answers to the question of using steroids with RFA or not.