Pulsed radiofrequency for low-back pain and sciatica

Image-Guided Minimally Invasive Treatment Options for Degenerative Lumbar Spine Disease: A Practical Overview of Current Possibilities

Lumbar back pain is one of the main causes of disability around the world. Most patients will complain of back pain at least once in their lifetime. The degenerative spine is considered the main cause and is extremely common in the elderly population. Consequently, treatment-related costs are a major burden to the healthcare system in developed and undeveloped countries. After the failure of conservative treatments or to avoid daily chronic drug intake, invasive treatments should be suggested. In a world where many patients reject surgery and prefer minimally invasive procedures, interventional radiology is pivotal in pain management and could represent a bridge between medical therapy and surgical treatment. We herein report the different image-guided procedures that can be used to manage degenerative spine-related low back pain. Particularly, we will focus on indications, different techniques, and treatment outcomes reported in the literature. This literature review focuses on the different minimally invasive percutaneous treatments currently available, underlining the central role of radiologists having the capability to use high-end imaging technology for diagnosis and subsequent treatment, allowing a global approach, reducing unnecessary surgeries and prolonged pain-reliever drug intake with their consequent related complications, improving patients' quality of life, and reducing the economic burden.

Pulsed Radiofrequency Decreases pERK and Affects Intracellular Ca2+ Influx, Cytosolic ATP Level, and Mitochondrial Membrane Potential in the Sensitized Dorsal Root Ganglion Neuron Induced by N-Methyl D-Aspartate

Background

The molecular mechanism of pulsed radiofrequency (PRF) in chronic pain management is not fully understood. Chronic pain involves the activation of specific N-Methyl D-Aspartate receptors (NMDAR) to induce central sensitization. This study aims to determine the effect of PRF on central sensitization biomarker phosphorylated extracellular signal-regulated kinase (pERK), Ca²⁺ influx, cytosolic ATP level, and mitochondrial membrane potential (Δψm) of the sensitized dorsal root ganglion (DRG) neuron following NMDAR activation.

Methods

This study is a true experimental in-vitro study on a sensitized DRG neuron induced with 80 µM NMDA. There are six treatment groups including control, NMDA 80 µM, Ketamine 100 µM, PRF 2Hz, NMDA 80 µM + PRF 2 Hz, and NMDA 80 µM + PRF 2 Hz + ketamine 100 µM. We use PRF 2 Hz 20 ms for 360 seconds. Statistical analysis was performed using the One-Way ANOVA and the Pearson correlation test with α=5%.

Results

In the sensitized DRG neuron, there is a significant elevation of pERK. There is a strong correlation between Ca²⁺, cytosolic ATP level, and Δψm with pERK intensity (p<0.05). PRF treatment decreases pERK intensity from 108.48 ± 16.95 AU to 38.57 ± 5.20 AU (p<0.05). PRF exposure to sensitized neurons also exhibits a Ca²⁺ influx, but still lower than in the unexposed neuron. PRF exposure in sensitized neurons has a higher cytosolic ATP level (0.0458 ± 0.0010 mM) than in the unexposed sensitized neuron (0.0198 ± 0.0004 mM) (p<0.05). PRF also decreases Δψm in the sensitized neuron from 109.24 ± 6.43 AU to 33.21 ± 1.769 AU (p<0.05).

Conclusion

PRF mechanisms related to DRG neuron sensitization are by decreasing pERK, altering Ca²⁺ influx, increasing cytosolic ATP level, and decreasing Δψm which is associated with neuron sensitization following NMDAR activation.

CT-guided Pulsed Radiofrequency Combined with Steroid Injection for Sciatica from Herniated Disk: A Randomized Trial

Background Evidence regarding effective nonsurgical management of sciatica remains limited. Purpose To determine a difference in effectiveness between combined pulsed radiofrequency (PRF) and transforaminal epidural steroid injection (TFESI) treatment versus TFESI alone for sciatic pain due to lumbar disk herniation. Materials and Methods This prospective multicenter double-blind randomized clinical trial was conducted between February 2017 and September 2019 in participants with sciatica due to lumbar disk herniation lasting 12 weeks or longer that was not responsive to conservative treatment. Study participants were randomly assigned to undergo one CT-guided treatment with combined PRF and TFESI (n = 174) or TFESI alone (n = 177). The primary outcome was leg pain severity, as assessed with the numeric rating scale (NRS) (range, 0-10) at weeks 1 and 52 after treatment. Secondary outcomes included Roland-Morris Disability Questionnaire (RMDQ) score (range, 0-24) and Oswestry Disability Index (ODI) score (range, 0-100). Outcomes were analyzed according to the intention-to-treat principle via linear regression. Results Mean age of the 351 participants (223 men) was 55 years ± 16 (SD). At baseline, NRS was 8.1 ± 1.1 in the PRF and TFESI group and 7.9 ± 1.1 in the TFESI group. NRS was 3.2 ± 0.2 in the PRF and TFESI group and 5.4 ± 0.2 in the TFESI group (average treatment effect, 2.3; 95% CI: 1.9, 2.8; P < .001) at week 1 and 1.0 ± 0.2 and 3.9 ± 0.2 (average treatment effect, 3.0; 95% CI: 2.4, 3.5; P < .001), respectively, at week 52. At week 52, the average treatment effect was 11.0 (95% CI: 6.4, 15.6; P < .001) for ODI and 2.9 (95% CI: 1.6, 4.3; P < .001) for RMDQ, favoring the combined PRF and TFSEI group. Adverse events were reported in 6% (10 of 167) of participants in the PRF and TFESI group and in 3% (six of 176) of participants in the TFESI group (eight participants did not complete follow-up questionnaires). No severe adverse events occurred. Conclusion In the treatment of sciatica caused by lumbar disk herniation, pulsed radiofrequency combined with transforaminal epidural steroid injection is more effective for pain relief and disability improvement than steroid injection alone. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Jennings in this issue.

STUDY PROTOCOL - pulsed radiofrequency in addition to transforaminal epidural steroid injection in patients with acute and subacute sciatica due to lumbosacral disc herniation: rationale and design of a phase III, multicenter, randomized, controlled trial

Lumbosacral disc herniation (LDH) represents the most common cause of sciatica. Currently, there is limited evidence about minimally invasive interventional therapies for the treatment of this condition. This paper presents the protocol for a multicenter, prospective, randomized, controlled, phase III trial evaluating if PRF in addition to TFESI leads to better outcomes in patients with sciatica due to LDH, compared to TFESI alone, during the first year after treatment (Pulsed Radiofrequency in Addition to TFESI for Sciatica [PRATS]). Eligible patients are between 18 and 75 years of age, suffer from sciatica of less than 12-week duration with pain intensity >4 on the Visual Analogue Scale (VAS) and have unilateral LDH compatible with symptoms at MRI. The Medical Ethics Committee of participating hospitals approved the study protocol. Patients will be randomized to receive either combined treatment (PRF and TFESI) or TFESI alone. The primary outcome will be the assessment of pain intensity with VAS at different timepoints from week-1 to 52 after treatment; secondary outcomes will include Roland Disability Questionnaire for sciatica and Oswestry Disability Index, evaluated at 4, 12 and 52 weeks. The follow-up will last 52 weeks for each patient. Statistical analysis will be performed on a per-protocol basis.

Pulsed Radiofrequency for Lumbar Facet Joint Pain: A Viable Therapeutic Option? A Retrospective Observational Study

Introduction

Low back pain (LBP) is a common problem, and facet joint pain is responsible for 15–45% of cases. Treatment is multidisciplinary, and when conservative measures are not sufficient, radiofrequency (RF) is often used. It allows the interruption of nociceptive input, producing a heat lesion in a continuous or pulsed mode.

Methods

Medical records of 60 patients who underwent pulsed RF denervation were examined. The standard procedure provided follow-up of pain intensity. Numerical rating scale (NRS) and Douleur Neuropathique en 4 Questions (DN4) were recorded before treatment, and 15 and 40 days, and 6 months after treatment. Oswestry Disability Index (ODI) and patient satisfaction were also recorded. Successful treatment was defined as more than a 50% reduction in the NRS scores at 6 months compared with pretreatment scores.

Results

Scores on the NRS and DN4 were statistically different over time (p < 0.05). Scores at 6 months were significantly decreased when compared with pretreatment scores (p < 0.05). ODI scores decreased during the follow-up period. No adverse effect was recorded and 57 patients (97%) reported successful pain relief.

Conclusions

Continuous RF is the gold standard in the management of lumbar facet joint pain. Pulsed RF is a promising technique: patients with chronic LBP who had not responded to conservative care tended to improve after pulsed RF. The procedure was well tolerated in the absence of contraindications, and reliable if the nerve endings regrew.