The mechanism of action of pulsed radiofrequency in reducing pain: a narrative review

Transforaminal Steroid Injection After Dorsal Root Ganglion Pulsed Radiofrequency (DRG-PRF): Impact on Pain Intensity and Disability

INTRODUCTION

Dorsal root ganglion pulsed radiofrequency (DRG-PRF) is frequently used for the treatment of chronic lumbar radicular pain with good outcomes in terms of pain management. Transforaminal epidural steroid injection (TFESI) is often administered immediately after DRG-PRF to increase the anti-inflammatory effects, but support for the synergic mechanism is lacking in the literature. The aim of this study was to investigate the potential role of TFESI immediately after DRG-PRF and its possible role on pain intensity and patient disability.

METHODS

A database of patients who underwent DRG-PRF with or without TFESI immediately after DRG-PRF was retrospectively analysed; propensity score matching was applied to the analysis to reduce possible bias. Pain intensity (numerical rating scale [NRS]) and Oswestry disability index (ODI) were recorded pre-operatively and at the 1- and 3-month follow-up in the two groups of patients.

RESULTS

A total of 252 patients were included in this retrospective analysis, 126 patients in the DRG-PRF + TFESI group and 126 patients in the DRG-PRF group after propensity score matching. Both groups displayed a significant reduction in pain intensity (NRS score reduction; p < 0.0001) and improvement in the ODI (p < 0.0001) from baseline at the 3-month follow-up. Interestingly, the use of TFESI after DRG-PRF was not associated with any clinical benefit as no difference in NRS and ODI was found between the two groups at the 1- and 3-month follow-ups.

CONCLUSIONS

Our study revealed a significant pain reduction and disability improvement after DRG-PRF in patients with lumbar radicular pain. Interestingly, no positive role of TFESI immediately after DRG-PRF was observed. These findings suggest that DRG-PRF provides substantial pain relief, and no added benefit is obtained with subsequent steroid injection. Future prospective studies with expanded follow-up periods are needed to confirm these findings.

Radiofrequency of suprascapular nerve as an analgesic strategy for chronic pain management. Systematic review and meta-analysis

INTRODUCTION

Chronic shoulder pain is highly prevalent in the general population. Many different analgesic strategies have been described, including radiofrequency treatment to the suprascapular nerve (RFS); however, the effectiveness this approach remains unclear, and no strong recommendation can be made. The aim of this systematic review is to analyse the latest clinical trials evaluating the effectiveness of RFS techniques applied to the suprascapular nerve in terms of management of chronic shoulder pain, post-procedural functionality, and adverse effects.

METHODS

We performed a systematic review of clinical trials retrieved from Medline, Embase and the CENTRAL databases. We included trials comparing RFS with other strategies, including placebo, that had as their primary outcome measures pain rated on a visual analogue scale, functionality rated on a shoulder pain and disability index (SPADI), and the incidence of adverse events. Risk of bias was analysed using the Cochrane RoB2 tool. Evidence was analysed using a random effects model and heterogeneity was quantified using the I2 test.

RESULTS

We identified 3030 trials, of which 8 met the inclusion criteria (n = 408). Seven had a high risk of bias. Pain intensity at 1 and 3 months was lower in patients receiving RFS, with a standardised mean difference (SMD) of -0.9 (95% CI [-1.1, 0.33], p = 0.29; I2 88%, p < 0.001) and -1.17 (95% CI [-2.49, 0.14], p = 0.08; I2 97%, p < 0.001), respectively. Functional compromise at 1 and 3 months decreased in patients receiving RFS, with an SMD of -0.31 (95% CI [-0.91, 0.29], p = 0.31; I2 80%, p < 0.001) and -1.54 (95% CI [-3.26, 0.19], p = 0.08; I2 98%, p < 0.001), respectively. No RFS-related adverse events were described.

CONCLUSION

The evidence suggests that RFS reduces pain and improves functionality. However, the certainty of the evidence is low.

Effect of pulsed radiofrequency to the suprascapular nerve (SSN) in treating frozen shoulder pain: A randomised controlled trial

BACKGROUND

Treatment for frozen shoulder (FS) focuses on pain control and restoring movement and strength through physical therapy. We aimed to evaluate the efficacy of pulsed radiofrequency (PRF) lesioning of the suprascapular nerve for the treatment of FS pain.

METHODS

Forty patients with FS were enrolled and randomly assigned into the intervention group (n = 20) that received PRF and a control group (n = 20) which received medical treatment (NSAIDs). Patients were followed-up for a total of three months. The primary outcome was the pain intensity, measured by the Numeric Pain Rating Scale (NRS). The secondary outcomes included shoulder range of motion (ROM) evaluation measured by simple shoulder test (SST); Likert-type-based patient satisfaction scale; and any adverse events (AEs) throughout the treatment period. All results were measured at baseline, at the end of one week, four weeks and 12 weeks after treatment.

RESULTS

At 12 weeks post-procedure, the intervention group significantly improved their pain (NRS dropped to 2.80 ± 0.5) and there was significant improvement in range of motion (SST from 6.55% ± 2.0% to 76.50% ± 6.5) compared to control group.

CONCLUSIONS

PRF lesioning of the SSN is a fast and effective modality in treating frozen shoulder pain and improving ROM for three months.

Anatomo-physiological basis and applied techniques of electrical neuromodulation in chronic pain

Chronic pain, a complex and debilitating condition, poses a significant challenge to both patients and healthcare providers worldwide. Conventional pharmacological interventions often prove inadequate in delivering satisfactory relief while carrying the risks of addiction and adverse reactions. In recent years, electric neuromodulation emerged as a promising alternative in chronic pain management. This method entails the precise administration of electrical stimulation to specific nerves or regions within the central nervous system to regulate pain signals. Through mechanisms that include the alteration of neural activity and the release of endogenous pain-relieving substances, electric neuromodulation can effectively alleviate pain and improve patients' quality of life. Several modalities of electric neuromodulation, with a different grade of invasiveness, provide tailored strategies to tackle various forms and origins of chronic pain. Through an exploration of the anatomical and physiological pathways of chronic pain, encompassing neurotransmitter involvement, this narrative review offers insights into electrical therapies' mechanisms of action, clinical utility, and future perspectives in chronic pain management.

Transforaminal pulsed radiofrequency and epidural steroid injection on chronic lumbar radiculopathy: A prospective observational study from a tertiary care hospital in Vietnam

BACKGROUND

Lumbosacral radicular syndrome (LRS) is probably the most frequent neuropathic pain syndrome, exaggerating medical and economy burden on developing countries, such as Vietnam. As a result, the urgence to find an approach which is both affordable and effective always puts great demand on medical researchers.

OBJECTIVES

Evaluate the effectiveness of transforaminal pulsed radiofrequency (PRF) stimulation on the dorsal root ganglion (DRG) and epidural steroid injection (ESI) in management of chronic lumbosacral radiculopathy.

METHODS

Seventy-six patients with chronic radicular pain were performed transforaminal PRF + ESI by neurosurgeons. Demographic characteristics and surgical outcomes were recorded on admission, pre-procedural and post-procedural for 1-month, 3-month, 6-month and 12-month follow-up. Primary outcome was measured by using Visual Analogue Scale (VAS), Oswestry disability index (ODI) and Straight Leg Raising Test (SLRT). Secondary outcome was subjectively collected based on short assessment of patients' satisfaction (SAPS).

RESULTS

Patients who received transforaminal PRF and ESI showed significant improvements on all three evaluation tools (VAS, ODI, SLRT), compared to that before treatment (p<0.001). Pain relief was achievable and long-lasting, which met patients' expectation. No significant complications were observed for 12 months follow-up.

CONCLUSION

Transforaminal PRF combined with ESI in management of lumbosacral radiculopathy should be a good method of choice for its effectiveness and safety in management of pain.

Pulsed Radiofrequency Ablation for Refractory Cancer-Related Leg Pain: A Case Report

Metastatic cancers often lead to distant metastasis, accompanied by debilitating symptoms such as chronic pain, which can be refractory to conventional analgesic modalities. Pulsed radiofrequency ablation (Pulsed RFA) has emerged as a promising intervention for neuropathic pain syndromes, offering long-lasting relief with minimal tissue damage. We present a case of a 36-year-old male with metastatic gastric adenocarcinoma and refractory leg pain due to femoral nerve involvement. Despite aggressive multimodal analgesia, the patient experienced persistent pain, necessitating alternative interventions. Pulsed RFA targeting the right L2-L4 dorsal root ganglia (DRG) provided significant and sustained pain relief, allowing improved functional status and reduced opioid requirements. This case underscores the potential of pulsed RFA as an effective intervention for refractory cancer-related pain, enhancing patients' comfort and quality of life. Further research is warranted to establish its long-term efficacy and safety.

Pulsed Radiofrequency for Auriculotemporal Neuralgia: A Case Report

Auriculotemporal neuralgia is a rare facial pain disorder with no therapeutic evidence for refractory cases. We described a male patient with right auriculotemporal neuralgia, refractory to anesthetic nerve blocks and botulinum toxin type A injections, who was successfully treated with pulsed radiofrequency without adverse events. Pulsed radiofrequency may be an effective and safe treatment for refractory auriculotemporal neuralgia.

A narrative review of pulsed radiofrequency for the treatment of carpal tunnel syndrome

OBJECTIVE

Carpal tunnel syndrome (CTS), which is the most common peripheral nerve entrapment syndrome, can commonly persist despite conservative treatment modalities such as wrist splinting or medications. Pulsed radiofrequency represents a minimally invasive pain intervention technique to alleviate pain. The literature was reviewed to establish the effectiveness of PRF therapy for CTS.

STUDY DESIGN

This is a narrative review of relevant articles on the effectiveness of PRF for CTS.

METHOD

Four databases, MEDLINE, Cochrane Central Register of Controlled Trials, Embase, OVID Emcare, and Web of Science, were systematically searched. 804 records were screened, and the reference lists of eligible articles were examined. For this review, eight extracted studies were narratively explored.

RESULTS

One case report, three retrospective cohorts, one observational prospective study, and three randomized-controlled trials were included. PRF likely provides both an analgesic and functional benefit in patients with mild to severe CTS, and it also shows benefit as an adjunct to carpal tunnel release surgery. Long-term data is limited. It also appears likely that steroid injection may represent a comparable treatment modality to PRF, and there have been positive results when these modalities are used together. Notably, all studies differed in their methodology, making direct comparisons between studies challenging.

CONCLUSIONS

The evidence for PRF in the treatment of CTS, across the range of spectrum of severity or peri-operative to CTS surgery, appears favorable and avoids known side effects of steroid injections. Potential mechanisms for PRF and future directions for research are explored.

Bipolar, high-voltage, long-duration pulsed radiofrequency ablation of the Gasserian ganglion for the treatment of trigeminal neuralgia in a patient with a cardiac implantable electronic device: illustrative case

BACKGROUND

One of the common methods of treating trigeminal neuralgia (TN) nowadays is radiofrequency therapy. However, it has serious limitations in patients with a cardiac pacemaker because of electromagnetic interference. Therefore, it is crucial to select optimal radiofrequency ablation parameters to make this procedure safe with favorable outcomes for such patients.

OBSERVATIONS

In this study, the authors present a case of a 70-year-old man with a history of cardiac pacemaker dependency and previous microvascular decompression with complaints of severe, constant facial pain. After reprogramming the cardiac implantable electronic device (CIED), the authors performed bipolar, high-voltage, long-duration pulsed radiofrequency therapy (PRFT) of the Gasserian ganglion under electrocardiography and pulse rate control in the pre-, intra-, and postoperative periods. There were no cardiovascular or neurological complications after PRFT. The patient reported relief of pain after the procedure, and at the 9-month follow-up, he was pain-free.

LESSONS

This clinical case demonstrates that the use of bipolar, high-voltage PRFT for TN treatment in patients with a CIED can be safe and effective, provided that the rules and pacemaker instructions are followed. It is necessary to use ablative treatment with caution and to guide the patient in collaboration with a cardiac surgeon and an anesthesiologist resuscitator.

Comprehensive Comparison of Therapeutic Efficacy of Radiofrequency Thermocoagulation and Pulsed Radiofrequency in Treatment of Elderly Patients with Thoracic Postherpetic Neuralgia

BACKGROUND We comprehensively compared the therapeutic efficacy of radiofrequency thermocoagulation (RFT) and pulsed radiofrequency (PRF) in the treatment of elderly patients with thoracic postherpetic neuralgia (PHN). MATERIAL AND METHODS We divided 149 elderly patients with thoracic PHN into 2 groups - the RFT group (n=79) and the PRF group (n=70) - based on the radiofrequency mode administered. The Visual Analog Scale (VAS), Athens Insomnia Scale (AIS), Generalized Anxiety Disorder 7 items (GAD-7), and Patient Health Questionnaire 9 items (PHQ-9) were used to analyze the degree of pain, sleep quality, and psychological state of patients before and 1 week, 1 month, 3 months, 6 months, and 12 months after treatment. RESULTS VAS, AIS, GAD-7, and PHQ-9 scores were significantly decreased after RFT and PRF treatment (P<0.001). There was no significant difference in VAS scores between the 2 groups at 1 week and 1 month after treatment (P>0.05). Then, VAS scores in the RFT group were significantly lower than those in the PRF group at 3, 6, and 12 months after treatment (P<0.001). At 1 week after treatment, there were no significant differences in AIS, GAD-7, and PHQ-9 scores between the 2 groups (P>0.05). However, the RFT group had significantly lower AIS, GAD-7, and PHQ-9 scores than the PRF group at 1, 3, 6, and 12 months after treatment (P<0.05). CONCLUSIONS RFT and PRF both effectively reduced pain in the distribution area of thoracic spinal neuropathy and improved the sleep quality and psychological state of elderly patients with thoracic PHN, but RFT had a better long-term effect.

Pulsed Radiofrequency 2 Hz Preserves the Dorsal Root Ganglion Neuron Physiological Ca2+ Influx, Cytosolic ATP Level, Δψm, and pERK Compared to 4 Hz: An Insight on the Safety of Pulsed Radiofrequency in Pain Management

Background

Pulsed radiofrequency (PRF) is beneficial for radicular pain and is commonly administered at pulse frequencies of 2 or 4 Hz. However, its effects on healthy neurons have not yet been widely studied. This study aims to determine the effect of PRF at 2 Hz and 4 Hz on the physiology of healthy dorsal root ganglion (DRG) neurons.

Methods

An in vitro experimental study was conducted using DRG neuron cultures divided into three groups. Control cells received no treatment, one cell group received 20 ms 2 Hz PRF for 360 s, and one cell group received a 4 Hz PRF 10 ms pulse for 360 s with similar energy. Ca2+ influx, mitochondrial membrane potential (Δψm), cytosolic Adenosine triphosphate (ATP), and phosphorylated extracellular signal-regulated kinase (pERK) levels were measured. The data were analyzed using the One-Way ANOVA variance with α=5%.

Results

DRG neurons exposed to PRF 2 Hz did not experience a significant change in Ca2+ influx, whereas PRF 4 Hz caused a significant decrease in Ca2+ influx compared to the basal level. PRF at 2 Hz did not cause a change in Δψm, whereas PRF at 4 Hz caused a significant decrease in Δψm (p<0.05). Both 2 and 4 Hz PRF resulted in a significant elevation in cytosolic ATP concentration, but the 2 Hz PRF had a higher cytosolic ATP than the 4 Hz group (p<0.05). Both 2 and 4 Hz did not show a significant difference in pERK intensity with respect to the control (p>0.05), indicating that there was no significant neuron activation.

Conclusion

Both frequencies did not significantly activate DRG neurons, but with similar energy delivery, PRF 2 Hz preserved the physiological properties of healthy neurons better than PRF 4 Hz did. A 2 Hz PRF is the preferred frequency in clinical applications for neuron-targeted therapy.

Spinal Injections: A Narrative Review from a Surgeon's Perspective

Spinal pain is one of most frequent complaints of the general population, which can cause decreased activities of daily living and absence from work. Among numerous therapeutic methods, spinal injection is one of the most effective treatments for spinal pain and is currently widely applied in the clinical field. In this review, spinal injection is discussed from a surgeon's perspective. Recently, although the number of spinal surgeries has been increasing, questions are arising as to whether they are necessary. The failure rate after spinal surgery is high, and its long-term outcome was reported to be similar to spinal injection. Thus, spinal surgeries should be performed conservatively. Spinal injection is largely divided into diagnostic and therapeutic blocks. Using diagnostic blocks, such as the diagnostic selective nerve root block, disc stimulation test, and diagnostic medial branch block (MBB), the precise location causing the pain can be confirmed. For therapeutic blocks, transforaminal nerve root injection, therapeutic MBB, and percutaneous epidural neuroplasty are used. When unbearable spinal pain persists despite therapeutic spinal injections, spinal surgeries can be considered. Spinal injection is usefully used to identify the precise location prior to a patient undergoing injection treatment or surgery and can reduce pain and improve quality of life, and help to avoid spinal surgery. Pain physicians should treat patients with spinal pain by properly utilizing spinal injection.

Previous Lumbar Spine Surgery Decreases the Therapeutic Efficacy of Dorsal Root Ganglion Pulsed Radiofrequency in Patients with Chronic Lumbosacral Radicular Pain

Chronic lumbosacral radicular pain (CLRP) as a possible adverse consequence of lumbar spine surgery represents a serious medical challenge. Pulsed radiofrequency of dorsal root ganglion (PRF-DRG) treatment is known to be effective in alleviating CLRP. This retrospective study compares the efficacy of a single CT-guided PRF-DRG procedure in the treatment of unilateral CLRP between patients without (non-PSS) and with (PSS) previous lumbar spine surgery. Non-PSS and PSS groups included 30 and 20 patients, respectively. Outcomes (pain intensity and disability) were evaluated by means of the visual analog scale (VAS) and Oswestry disability index (ODI) immediately after the procedure (VAS), as well as three and six months after the procedure, respectively. Non-PSS group showed a significant (p ˂ 0.001) decrease of VAS (median) at all follow-up intervals (from 6 to 4; 4; 4.5 points, respectively). The PSS group showed a significant yet transient VAS (median) decrease (from 6 to 5 points) immediately after the procedure only (p < 0.001). The decrease of VAS was more pronounced in the non-PSS group after three and six months (p = 0.0054 and 0.011, respectively) in intergroup comparison. A relative decrease of VAS ≥ 50% during follow-up was achieved in 40%; 43.3%; 26.7% (non-PSS), and 25%; 5%; 0% (PSS) of patients. ODI (median) significantly decreased in the non-PSS group (from 21.5 to 18 points) at three and six months (p = 0.014 and 0.021, respectively). In conclusion, previous lumbar spine surgery decreases the therapeutic efficacy of PRF-DRG procedure in CLRP patients.

Use of QR Codes for Promoting a Home-Based Therapeutic Exercise in Patients with Lumbar Disc Herniation and Lumbar Spinal Stenosis: A Prospective Randomized Study

Purpose

In the current study, we investigated the usefulness of the quick response (QR) code linked to the source of a video of home-based therapeutic exercise to promote home-based therapeutic exercise in patients with LDH and LSS.

Patients and Methods

Forty patients with LDH and LSS were included in this study. The patients were randomly assigned to one of two groups: QR codes or control groups (20 patients per group). The QR code group received QR code stickers linked with a video that includes a demonstration on how to exercise for the back muscles. We instructed the patients to perform home-based therapeutic exercises three or more days a week. Patients in the control group were asked to perform the therapeutic exercise without providing a QR code to them. The primary outcome was the number of exercises per week. The scores of the numeric rating scale (NRS) and Oswestry disability index (ODI) were investigated as secondary outcomes.

Results

The patients in the QR code group exercised for the lower back muscles on average about two times a week, and 40% of the patients in the QR code group performed the exercise three or more days a week. However, almost no patients in the control group performed therapeutic exercises. Patients in the QR code group showed significantly lower ODI scores at the 1-month and 2-month follow-ups compared with the control group. In addition, the patients who exercised ≥3 times per week showed more improvement in the disability than those who exercised <3 times per week. The NRS scores for lower back pain and radicular leg pain were not significantly different between the QR code and control groups.

Conclusion

We found that QR codes can be useful for encouraging patients with LDH or LSS to perform home-based therapeutic exercises.