Radiofrequency denervation for chronic low back pain

Senescence of endplate osteoclasts induces sensory innervation and spinal pain

Spinal pain affects individuals of all ages and is the most common musculoskeletal problem globally. Its clinical management remains a challenge as the underlying mechanisms leading to it are still unclear. Here, we report that significantly increased numbers of senescent osteoclasts (SnOCs) are observed in mouse models of spinal hypersensitivity, like lumbar spine instability (LSI) or aging, compared to controls. The larger population of SnOCs is associated with induced sensory nerve innervation, as well as the growth of H-type vessels, in the porous endplate. We show that deletion of senescent cells by administration of the senolytic drug Navitoclax (ABT263) results in significantly less spinal hypersensitivity, spinal degeneration, porosity of the endplate, sensory nerve innervation, and H-type vessel growth in the endplate. We also show that there is significantly increased SnOC-mediated secretion of Netrin-1 and NGF, two well-established sensory nerve growth factors, compared to non-senescent OCs. These findings suggest that pharmacological elimination of SnOCs may be a potent therapy to treat spinal pain.

Cryoneurolysis versus radiofrequency ablation outcome on pain experience in chronic low back pain (COPE): a single-blinded randomised controlled trial

OBJECTIVE

A comparison of cryoneurolysis or radio frequency (RF) with placebo in patients with facetogenic chronic low back pain (LBP) for patient global impression of change (PGIC), pain intensity, function and quality of life, with 1-year follow-up.

DESIGN

Single-centre, single-blinded placebo-controlled randomised controlled trial.

SETTING

Single-centre study.

PARTICIPANTS

Inclusion from March 2020 to September 2022: consenting adults over 18 years of age, LBP>3 months, average Numeric Rating Scale LBP≥4 average last 14 days and a positive response to a diagnostic medial branch block (>50% pain reduction after 60 min).

INTERVENTIONS

120 patients were block randomised 1:1:1 to cryoneurolysis, RF or placebo of the medial branch nerves. Physical therapy was added after 4 weeks for all groups.

MAIN OUTCOME MEASURES

Primary outcome was PGIC 4 weeks after the intervention. Secondary outcomes included pain intensity (Numeric Rating Scale, NRS), quality of life (Short Form 36, EQ-5D-5L), disability (Oswestry Disability Index), depression (Major Depression Inventory) and catastrophising (Pain Catastrophising Scale). Outcomes were measured at 4 weeks, 3, 6 and 12 months.

RESULTS

There was no statistically significant difference in PGIC at 4 weeks between cryoneurolysis and placebo (risk ratio (RR) 2; 95% CI 0.75 to 5.33, p=0.17) and RF and placebo (RR 1.6; 95% CI 0.57 to 4.49, p=0.37), except PGIC for cryoneurolysis at 6-month follow-up (RR 5.1; 95% CI 1.20 to 22.03, p=0.03). No statistically significant differences were found in secondary follow-up endpoints.

CONCLUSIONS

Denervation of the medial branch nerve by either cryoneurolysis or RF compared with placebo did not demonstrate significant improvement in PGIC, pain intensity, function and quality of life in patients with facetogenic chronic LBP at short-term or long-term follow-up.

TRIAL REGISTRATION NUMBER

NCT04786145.

Senescence of endplate osteoclasts induces sensory innervation and spinal pain

Spinal pain affects individuals of all ages and is the most common musculoskeletal problem globally. Its clinical management remains a challenge as the underlying mechanisms leading to it are still unclear. Here, we report that significantly increased numbers of senescent osteoclasts (SnOCs) are observed in mouse models of spinal hypersensitivity, like lumbar spine instability (LSI) or aging, compared to controls. The larger population of SnOCs is associated with induced sensory nerve innervation, as well as the growth of H-type vessels, in the porous endplate. We show that deletion of senescent cells by administration of the senolytic drug Navitoclax (ABT263) results in significantly less spinal hypersensitivity, spinal degeneration, porosity of the endplate, sensory nerve innervation and H-type vessel growth in the endplate. We also show that there is significantly increased SnOC-mediated secretion of Netrin-1 and NGF, two well-established sensory nerve growth factors, compared to non-senescent OCs. These findings suggest that pharmacological elimination of SnOCs may be a potent therapy to treat spinal pain.

Efficacy of radiofrequency in lumbar facet joint pain: a systematic review and meta-analysis of placebo-controlled randomized controlled trials

BACKGROUND

Lumbar facet joint pain (LFJP) is one of the main causes of chronic low back pain (LBP) and can be treated using radiofrequency (RF) sensory denervation. The aim of this work is to analyze the efficacy of RF in LFJP through a systematic review and meta-analysis of randomized controlled trials (RCTs) with placebo control.

MATERIALS AND METHODS

A systematic search was conducted in the Medline (PubMed), Scopus, Web of Science databases, and the Cochrane Central Register of Controlled Trials (CENTRAL). The variables of interest were pain, functional status, quality of life (QoL), and global perceived effect (GPE) measured at different time intervals: short (< 3 months), medium (> 3 and < 12 months), and long term (> 12 months).

RESULTS

Eight RCTs with placebo control were included. RF showed significant benefits over placebo in pain relief in the short (MD - 1.01; 95% CI - 1.98 to -0.04; p = 0.04), medium (MD - 1.42; 95% CI - 2.41 to - 0.43; p = 0.005), and long term (MD - 1.12; 95% CI - 1.57 to - 0.68; p < 0.001), as well as improvement in functional disability in the short (SMD - 0.94; 95% CI - 1.73 to - 0.14; p = 0.02) and long term (SMD - 0.74; 95% CI - 1.09 to - 0.39; p < 0.001). No statistically significant differences were observed in QoL or quantitative GPE, but benefits for RF were observed in dichotomous GPE in the medium (OR 0.19; 95% CI 0.07-0.52; p = 0.001) and long term (OR 0.22; 95% CI 0.06-0.78; p = 0.02). Subgroup analyses showed more benefits for RF in LBP < 1 year in the short term and in RCTs that did not require performing an MRI for patient selection.

CONCLUSIONS

RF demonstrated significant improvement in pain and functionality, but the benefits in terms of QoL and GPE are inconclusive. Future clinical trials should investigate the long-term effects of RF, its impact on quality of life, and define appropriate criteria for patient selection.

[Radiofrequency denervation of the spine and the sacroiliac joint : A systematic literature search according to GRADE with new German S3 guideline]

BACKGROUND

This article summarizes the results of the German guideline on radiofrequency denervation of the facet joints and the sacroiliac joint. Evidence on the indications, test blocks and technical parameters are presented.

OBJECTIVE

The aim is to avoid overtreatment and undertreatment, which is also of socioeconomic importance.

MATERIAL AND METHOD

A systematic evaluation of the literature was carried out according to the grading of recommendations assessment, development and evaluation (GRADE) approach. A multidisciplinary guideline group has developed recommendations and statements.

RESULTS

Statements and recommendations were given for 20 key questions. There was an 87.5% consensus for 1 recommendation and 100% consensus for all other recommendations and statements. The guideline was approved by all scientific medical societies involved. Specific questions included the value of the medical history, examination and imaging, the need for conservative treatment prior to an intervention, the importance of test blocks (medial branch block and lateral branch block), choice of imaging for denervation, choice of trajectory, the possibility to influence the size of the lesion, stimulation, the possibility of revision, sedation and decision support for patients with anticoagulants, metal implants and pacemakers and advice on how to avoid complications.

CONCLUSION

Selected patients can benefit from well-performed radiofrequency denervation. The guideline recommendations are based on very low to moderate quality of evidence.

Radiofrequency Denervation of the Spine and the Sacroiliac Joint: A Systematic Review based on the Grades of Recommendations, Assesment, Development, and Evaluation Approach Resulting in a German National Guideline

STUDY DESIGN

Systematic review of the literature and subsequent meta-analysis for the development of a new guideline.

OBJECTIVES

This manuscript summarizes the recommendations from a new clinical guideline published by the German Spine Society. It covers the current evidence on recommendations regarding the indication, test blocks and use of radiofrequency denervation. The guidelines aim is to improve patient care and efficiency of the procedure.

METHODS

A multidisciplinary working group formulated recommendations based on the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) approach and the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument.

RESULTS

20 clinical questions were defined for guideline development, with 87.5% consensus achieved by committee members for one recommendation and 100% consensus for all other topics. Specific questions that were addressed included clinical history, examination and imaging, conservative treatment before injections, diagnostic blocks, the injected medications, the cut-off value in pain-reduction for a diagnostic block as well as the number of blocks, image guidance, the cannula trajectories, the lesion size, stimulation, repeat radiofrequency denervation, sedation, cessation or continuation of anticoagulants, the influence of metal hardware, and ways to mitigate complications.

CONCLUSION

Radiofrequency (RF) denervation of the spine and the SI joint may provide benefit to well-selected individuals. The recommendations of this guideline are based on very low to moderate quality of evidence as well as professional consensus. The guideline working groups recommend that research efforts in relation to all aspects of management of facet joint pain and SI joint pain should be intensified.

Multifidus Denervation After Radiofrequency Ablation of the Medial Nerve Alters the Biomechanics of the Spine-A Computational Study

Radiofrequency ablation of the medial branch is commonly used to treat chronic low back pain involving facet joints, which accounts for 12% to 37% of the total cases of chronic low back pain. An adverse effect of this procedure is the denervation of the multifidus muscle, which may lead to its atrophy which can affect the spine and possibly disc degeneration. This study aims to quantify changes in joint angles and loading caused by multifidus denervation after radiofrequency ablation. AnyBody model of the torso was used to evaluate intervertebral joints in flexion, lateral bending, and torsion. Force-dependent kinematics was used to calculate joint angles and forces. These dependent variables were investigated in intact multifidus, unilateral, and bilateral ablations of L3L4, L4L5, and L5S1 joints. The results showed pronounced angular joint changes, especially in bilateral ablations in flexion, when compared with other cases. The same changes' trend from intact to unilaterally then bilaterally ablated multifidus occurred in joint angles of lateral bending. Meanwhile, joint forces were not adversely affected. These results suggest that multifidus denervation after radiofrequency ablation affects spinal mechanics. Such changes may be associated with abnormal tissue deformations and stresses that can potentially alter their mechanobiology and homeostasis, thereby possibly affecting the health of the spine.

International Society for the Advancement of Spine Surgery Statement: Restorative Neurostimulation for Chronic Mechanical Low Back Pain Resulting From Neuromuscular Instability

This International Society for the Advancement of Spine Surgery statement has been generated to respond to growing requests for background, supporting literature and evidence, and proper coding for restorative neurostimulation for chronic low back pain. Chronic low back pain describes the diverse experience of a significant proportion of the population. Conservative management of these patients remains the predominant care pathway, but for many patients, symptom relief is poor. The application of new techniques in patients who have exhausted traditional care paradigms should be undertaken with a detailed understanding of the pathology being treated, the mechanisms involved, and the data supporting efficacy. This statement on restorative neurostimulation places this technology in the context of the current understanding of the etiology of mechanical low back pain and the currently available evidence for this technique. In an appropriately selected cohort with a specific subset of chronic low back pain symptoms, this technique may provide benefit to payers and patients.

Abnormal Paresthesias Associated With Radiofrequency Ablation of Lumbar Medial Branch Nerves: A Case Report

Radiofrequency ablation (RFA) is an effective treatment that has occasionally been associated with transient paresthesias. This case report details an unusual presentation of paresthesias after lumbar medial branch RFA. A 48-year-old female patient reported pain, numbness, and swelling on the left buttock and posterolateral thigh. A physical exam revealed allodynia over the left posterolateral thigh without neurologic deficits two weeks after RFA of the left-sided lumbar medial branch nerves innervating the L4-L5 and L5-S1 facet joints. Shortly after the RFA of the contralateral targets, the patient complained of numbness of the right-sided lower back extending laterally from the right hip to the right knee. Imaging confirmed the appropriate placement of all needles in both procedures. Both instances of paresthesias resolved over time. This case report aims to demonstrate that RFA can be associated with unusual paresthesias and that these adverse effects do not warrant excessive workup.

Comparative efficacy of radiofrequency denervation in chronic low back pain: A systematic review and network meta-analysis

Background

Facet joint pain is a common cause of chronic low back pain (CLBP). Radiofrequency (RF) denervation is an effective treatment option.

Purpose

A systematic review and network meta-analysis (NMA) was performed to evaluate and compare the efficacy and effectiveness of different RF denervation treatments in managing facet joint-derived CLBP.

Methods

The Cochrane Library, Embase, PubMed, and China Biology Medicine were searched to identify eligible randomized controlled trials (RCTs) from January 1966 through December 2021. Interventions included conventional radiofrequency denervation (CRF), pulsed radiofrequency denervation (PRF), pulsed radiofrequency treatment of the dorsal root ganglia (PRF-DRG), radiofrequency facet capsule denervation (RF-FC), and radiofrequency ablation under endoscopic guidance (ERFA). The outcome was the mean change in visual analog scale (VAS) score from baseline. A random-effects NMA was used to compare the pain relief effects of the interventions over the short term (≤6 months) and long term (12 months). The rank of effect estimation for each intervention was computed using the surface under the cumulative ranking curve.

Results

A total of 10 RCTs with 715 patients met the inclusion criteria. Moderate evidence indicated that CRF denervation had a greater effect on pain relief than sham control in the short term (standardized mean difference (SMD) −1.58, 95% confidence intervals (CI) −2.98 to −0.18) and the long term (SMD −4.90, 95% CI, −5.86 to −3.94). Fair evidence indicated that PRF denervation was more effective than sham control for pain over the long term (SMD −1.30, 95% CI, −2.17 to −0.43). Fair evidence showed that ERFA denervation was more effective for pain relief than sham control in the short term (SMD −3.07, 95% CI, −5.81 to −0.32) and the long term (SMD −4.00, 95% CI, −4.95 to −3.05). Fair evidence showed that RF-FC denervation was more effective for pain relief than sham control in the long term (SMD −1.11, 95% CI, −2.07 to −0.15). A fair level of evidence indicated that PRF-DRG denervation was more effective for pain relief than sham control in the short term (SMD −5.34, 95% CI, −8.30 to −2.39).

Conclusion

RF is an effective option for patients diagnosed with facet joint-derived CLBP.

Systematic Review Registration: Identifier: CRD42022298238.

One-year results of minimally invasive fusion surgery of the sacroiliac joint as an alternative treatment after failed endoscopic thermal coagulation

BACKGROUND

While pain in the severe sacroiliac joint (SIJ) is a common cause of lower back pain, SIJ disease is often overlooked as a diagnosis.

OBJECTIVE

This study examines the extent of sufficient long-term pain relief and functional improvement in patients with SIJ syndrome that are treated with thermocoagulation. Some patients treated with thermocoagulation noted initial improvement, but the functionality and pain relief had limited duration and efficacy. Patients with insufficient improvement were recommended to undergo fusion surgery as an option for better and longer lasting results.

METHOD

Patients with a long history of back or pelvic problems were selected for the study. Endoscopic thermal coagulation of the SIJ was carried out. The follow-up examinations took place after 1, 3, 6, 12 months. In patients with insufficient pain relief and functionality after thermocoagulation, a fusion surgery was performed. The results of the fusion surgery were documented over a 12-month follow-up period. To carry out the statistical evaluation visual analog scale (VAS), Oswestry-Disability-Index (ODI) and the consumption of opioids were recorded.

RESULTS

Forty-eight patients were included. The mean VAS values 12 months after thermocoagulation were 68.9. The ODI after 12 months was very near or somewhat higher than their baseline prior to the thermocoagulation. Thus, a fusion surgery was recommended. Thirty-three patients agreed to the fusion operation. The VAS values 12 months after fusion surgery decreased to 53.1. Analogous to the VAS values, the Oswestry index (ODI) showed a significant improvement after the fusion operation.

CONCLUSION

The success of surgical intervention in 88% of the SIJ syndrome patients with inadequate results 12 months after thermocoagulation proves the superiority of SIJ fusion surgery. This study showed long-lasting pain relief by an average of 65% and a median improvement in functional impairments of 60%. In view of these results, fusion surgery should be considered for patients without sufficient success of thermocoagulation.

Evaluation of the Effect of Radiofrequency Denervation on Quality of Life of Patients with Facet Joint Syndrome by Oswestry Disability Index Score and Visual Analogue Scale Score

In this study, we aimed to investigate the effect of radiofrequency denervation procedure on pain and quality of life of patients with facet joint syndrome. Forty-seven patients who were admitted to our hospital with low back pain and diagnosed with facet joint syndrome between January 2018 and December 2018 were included in our study. The patients underwent denervation with radiofrequency under fluoroscopy in a sterile operating room condition. The pre-procedure and 6th month follow-up VAS (visual analogue scale) and ODI (Oswestry disability index) scores of the patients were recorded. When the demographic data of the patients were analysed, the mean age of the patients was found to be 52. Of the patients, 61.7% were female. In the evaluation of VAS and ODI scores, which we used to measure the efficiency of the procedure, the 6th month values were found to be statistically lower than the pre-procedure values (p&lt;0.05). The first treatment for facet joint syndrome is bed rest and medical treatment. Resistant cases also benefit from physical therapy and intra-articular steroid injection. In patients unresponsive to these treatments, denervation with radiofrequency appears to be an effective method. At least two levels must be performed for the procedure to be successful. Studies have shown that pain decreases in the long term (6-12 months) and quality of life increases. We also obtained similar results in our studies. In conclusion, we think that RF (radiofrequency) can be used as an effective method in cases where other treatments fail.

Investigation of Effectiveness of Pulsed Radiofrequency With Multifunctional Epidural Electrode for Low Back Pain

Aim: Low back pain affects many people at some point in their life. Whenever pharmacologic and other conservative treatments of chronic pain fail, ablative and interventional methods are attempted on the assumption that interrupting nerve conduction prevents central pain cognition. Pulsed radiofrequency using multifunctional epidural electrodes can be used for multiple etiologies of chronic low back and leg pain with a low complication rate and minimal side effects. Methods: The records of the 188 patients who underwent pulsed radiofrequency with multifunctional epidural electrode between October 2014 and March 2017 in Algology clinic were examined retrospectively. Visual analogue scale (VAS) for pain, response to straight leg raising test (SLR), lumbar range of motion, analgesic use, patient satisfaction score, need for open operation or other interventional procedure were collected.

Results: VAS and SLR tests were found to be significantly improved compared with the preoperative values. The VAS scores at the 10th day and first, third and sixth months were significantly decreased compared to baseline scores (p<0.001). Also, SLR tests were significantly improved compared to baseline scores at the same intervals (p<0.001).

Conclusion: Pulsed radiofrequency with multifunctional epidural electrode is a safe and effective method for low back pain which is caused by several pathologies.

Efficacy of Radiofrequency Neurotomy in Chronic Low Back Pain: A Systematic Review and Meta-Analysis

Purpose

The objective of the systematic review and meta-analysis is to evaluate the efficacy of radiofrequency neurotomy as a therapeutic lumbar facet joint intervention.

Patients and Methods

Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, a systematic review and meta-analysis was performed. A comprehensive literature search of multiple data sources from 1966 to September 2020 including manual searches of bibliography of known review articles was performed. The inclusion criteria were based on the selection of patients with chronic low back pain with diagnosis confirmed based on controlled diagnostic blocks and with the publication of at least 6 months of results of appropriate outcome parameters. Quality assessment of the trials was performed with Cochrane review criteria and interventional pain management techniques-quality appraisal of reliability and risk of bias assessment (IPM-QRB). The level of evidence of effectiveness is classified at five levels ranging from Level I to Level V. The primary outcome measure was a significant reduction in pain, eg, short term (up to 6 months) and long term (more than 6 months). The secondary outcome measure was an improvement in functional status.

Results

A total of 12 randomized controlled trials (RCTs) met the inclusion criteria for evaluating the efficacy of lumbar radiofrequency neurotomy. Radiofrequency neurotomy showed Level II evidence for efficacy for both the short term and long term.

Conclusion

This systematic review of the assessment of the efficacy of radiofrequency neurotomy in managing chronic low back pain was based on the inclusion of 12 RCTs with a diagnostic block and at least 6 months of follow-up results that showed Level II evidence for both short-term and long-term improvement.

Latest Evidence-Based Application for Radiofrequency Neurotomy (LEARN): Best Practice Guidelines from the American Society of Pain and Neuroscience (ASPN)

Radiofrequency neurotomy (RFN), also known as radiofrequency ablation (RFA), is a common interventional procedure used to treat pain from an innervated structure. RFN has historically been used to treat chronic facet-joint mediated pain. The use of RFN has more recently expanded beyond facet-joint mediated pain to peripherally innervated targets. In addition, there has also been the emergence of different radiofrequency modalities, including pulsed and cooled RFN. The use of RFN has been particularly important where conservative and/or surgical measures have failed to provide pain relief. With the emergence of this therapeutic option and its novel applications, the American Society of Pain and Neuroscience (ASPN) identified the need for formal evidence-based guidance. The authors formed a multidisciplinary work group tasked to examine the latest evidence-based medicine for the various applications of RFN, including cervical, thoracic, lumbar spine; posterior sacroiliac joint pain; hip and knee joints; and occipital neuralgia. Best practice guidelines, evidence and consensus grading were provided for each anatomical target.

Do people with acute low back pain have an attentional bias to threat-related words?

OBJECTIVES

It has been hypothesised that attentional bias to environmental threats can contribute to persistent pain. It is unclear whether people with acute low back pain (LBP) have an attentional bias to environmental threats. We investigated if attentional bias of threat related words is different in people with acute LBP and pain-free controls.

METHODS

People with acute LBP and pain-free people completed a free viewing eye tracking task. Participants were simultaneously presented with two words, a threat related word and a neutral control word. Threat related words were general threat, affective pain and sensory pain. We conducted linear mixed models to detect differences between acute LBP and pain-free participants on five eye tracking outcome measures (dwell time, first fixation, latency to first fixation, first run dwell time and number of fixations). We calculated absolute reliability, (standard error of measure), and relative reliability (intraclass correlation coefficients [ICC 2,1]) for each eye tracking outcome measures.

RESULTS

We recruited 65 people with acute LBP and 65 pain-free controls. Participants with acute LBP had a higher proportion of fixations towards the affective pain words (M=0.5009, 95% CI=0.4941, 0.5076) than the pain-free controls had (M=0.4908, 95% CI=0.4836, 0.4979), mean between group difference = -0.0101, 95% CI [-0.0198, -0.0004], p=0.0422. There was no difference between acute LBP and pain-free controls for the remaining eye tracking outcome measures (all p>0.05). The only outcome measure that had an ICC of more than 0.7 was the latency to first fixation (affective pain words ICC=0.73, general threat words ICC=0.72).

CONCLUSIONS

When compared with pain-free controls, people with acute LBP looked more often at affective pain words relative to neutral control words. This may indicate a form of engagement bias for people with acute LBP. Attentional bias was not consistent across outcome measures or word groups. Further research is needed to investigate the potential role of attentional bias in the development of persistent pain.

Cryoneurolysis' outcome on pain experience (COPE) in patients with low-back pain: study protocol for a single-blinded randomized controlled trial

Background

Low-back pain, including facet joint pain, accounts for up to 20 % of all sick leaves in DenmarkA proposed treatment option is cryoneurolysis. This study aims to investigate the effect of cryoneurolysis in lumbar facet joint pain syndrome.

Methods

A single-center randomized controlled trial (RCT) is performed including 120 participants with chronic facet joint pain syndrome, referred to the Department of Neurosurgery, Aarhus University Hospital. Eligible patients receive a diagnostic anesthetic block, where a reduction of pain intensity ≥ 50 % on a numerical rating scale (NRS) is required to be enrolled. Participants are randomized into three groups to undergo either one treatment of cryoneurolysis, radiofrequency ablation or placebo. Fluoroscopy and sensory stimulation is used to identify the intended target nerve prior to administrating the above-mentioned treatments. All groups receive physiotherapy for 6 weeks, starting 4 weeks after treatment. The primary outcome is the patients’ impression of change in pain after intervention (Patient Global Impression of Change (PGIC)) at 4 weeks follow-up, prior to physiotherapy. Secondary outcomes are a reduction in low-back pain intensity (numeric rating scale) and quality of life (EQ-5D, SF-36) and level of function (Oswestry Disability Index), psychological perception of pain (Pain Catastrophizing Scale) and depression status (Major Depression Inventory).

Data will be assessed at baseline (T0), randomization (T1), day one (T2), 4 weeks (T3), 3 (T4), 6 (T5) and 12 months (T6).

Discussion

This study will provide information on the effectiveness of cryoneurolysis vs. the effectiveness of radiofrequency ablation or placebo for patients with facet joint pain, and help to establish whether cryoneurolysis should be implemented in clinical practice for this patient population.

Trial registration

The trial is approved by the ethical committee of Central Jutland Denmark with registration number 1-10-72-27-19 and the Danish Data Protection Agency with registration number 666,852. The study is registered at Clinicaltrial.gov with the ID number NCT04786145.

Methylene Blue Application to Lessen Pain: Its Analgesic Effect and Mechanism

Methylene blue (MB) is a cationic thiazine dye, widely used as a biological stain and chemical indicator. Growing evidence have revealed that MB functions to restore abnormal vasodilation and notably it is implicated even in pain relief. Physicians began to inject MB into degenerated disks to relieve pain in patients with chronic discogenic low back pain (CDLBP), and some of them achieved remarkable outcomes. For osteoarthritis and colitis, MB abates inflammation by suppressing nitric oxide production, and ultimately relieves pain. However, despite this clinical efficacy, MB has not attracted much public attention in terms of pain relief. Accordingly, this review focuses on how MB lessens pain, noting three major actions of this dye: anti-inflammation, sodium current reduction, and denervation. Moreover, we showed controversies over the efficacy of MB on CDLBP and raised also toxicity issues to look into the limitation of MB application. This analysis is the first attempt to illustrate its analgesic effects, which may offer a novel insight into MB as a pain-relief dye.

[Interdisciplinary position paper: the value of radiofrequency denervation in the treatment of chronic pain]

Radiofrequency denervation has been established for many years as an important minimally invasive procedure for the treatment of chronic pain conditions. Positive experiences of many users for various indications are contrasted by a nonuniform evidence. With meticulous patient selection and correct assessment of the indications a longer term reduction of pain, a reduced need for analgesics and an improvement in the quality of life can be achieved. The aim of this interdisciplinary position paper is to present the value of radiofrequency denervation in the treatment of chronic pain. The summarized recommendations of the expert group are based on the available evidence and on the clinical experiences of Austrian centers that frequently implement the procedure. The position paper contains recommendations on patient selection and proven indications. We discribe safety aspects, complications, side effects and contraindications.

Prospective analysis of radiofrequency denervation in patients with chronic low back pain

BACKGROUND

To analyse the effectiveness of lumbar rhizolysis in patients with facet joint-related chronic low back pain and to study the influence of various variables on the results. Facet joints are thought to be responsible for up to 15% of all cases of chronic low back pain. Although radiofrequency denervation of these joints is a common procedure, there is currently no solid evidence to allow the selection of patients who may be candidates for this technique to be selected or the effectiveness and safety thereof to be demonstrated.

METHODS

A prospective analytical study of 100 patients treated with lumbar rhizolysis at the Hospital Universitario de Cabueñes (Gijón, Spain) between 2016 and 2019. Various demographic variables, the evolution of the visual analogue scale (VAS), the Oswestry Disability Index (ODI) and consumption of analgesics pre- and postoperatively was analysed at 2, 6, 12 and 24 months.

RESULTS

The mean age of our sample was 57.8 years (27.0-85.5), with a BMI of 27.09 (16.14-46.22), and 63.8% of subjects were female. The mean duration of the symptoms prior to the intervention was 8.7 years, with 28.7% of subjects having a history of spinal surgery. The intervention resulted in a significant reduction in analgesics consumption. Moreover, a statistically significant reduction in pure low back pain, radiating pain and in the ODI in the short to medium term was observed with respect to baseline. We found that being female, having a history of prior low back surgery, the time to progression and the analgesic level consumed by the patient were related to a greater disability.

CONCLUSIONS

Lumbar rhizolysis results in a significant reduction in pain and functional disability in patients with chronic low back pain in both the short- and medium-term, and reduces the need for analgesics consumption.

How do people in China think about causes of their back pain? A predominantly qualitative cross-sectional survey

Background

Low back pain (LBP) is the second highest cause of health burden in China. Delayed recovery, poor clinical outcomes and persistence of LBP are associated with negative pain beliefs about LBP. Chinese philosophies are nested into the daily life of people in China, which is likely to influence pain beliefs. However, there is lack of knowledge about people’s discourses regarding their LBP in China. The primary aim of this study was to explore the discourses underlying the beliefs of people in China about what causes their persistent or recurrent LBP. The secondary aim was to investigate the sources of these pain beliefs.

Methods

People (n = 152) from South Central, East and North Mainland China with LBP completed an online survey about what they believed caused their persistent or recurrent LBP and where these understandings came from. Potential causes of persistent or recurrent LBP were explored qualitatively using discourse analysis. The sources of these discourses were assessed by descriptive statistics with conventional content analysis.

Results

Five discourses were identified to underpin participants’ beliefs about what caused their persistent or recurrent LBP, namely: (1) biomedical problems (66.4%), (2) unbalanced lifestyle (48.7%), (3) menstruation and ‘kidney’ status (9.2%), (4) the ‘Five Elements’ imbalance (7.9%), and (5) energy status (5.9%). Most participants responded that their pain beliefs were based on information derived from healthcare professionals (59.2%), followed by the internet (24.3%) and family (23.0%).

Conclusions

People from moderately and well-developed parts of Mainland China think predominantly in line with a Western biomedical viewpoint about their LBP. Traditional Chinese medicine related pain beliefs mainly to the concept of ‘balance’ were evident on contemporary Chinese society’s understandings of LBP. These cultural beliefs could be relevant to consider in LBP management and involve healthcare professionals, family and patient in this process.

Radiofrequency denervation for chronic back pain: a systematic review and meta-analysis

OBJECTIVES

To assess the effectiveness of radiofrequency denervation (RD) of lumbosacral anatomical targets for the management of chronic back pain.

DESIGN

Systematic review and meta-analysis of randomised controlled trials (RCTs).

METHODS

A database search (Medline, Medline in Process, Embase, CINHAL and the Cochrane library) was conducted from January 2014 to April 2019 for placebo or no-treatment controlled trials of RD for the management of chronic back pain. Included trials were quality assessed using the Cochrane Risk-of-Bias Tool and the quality of outcomes assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Meta-analysis was conducted to calculate mean difference (MD) in post-treatment Pain Score.

RESULTS

Nineteen RCTs were included in the review. There appears to be short-term pain relief (1-3 months) provided by RD of the sacroiliac joint (five trials, MD -1.53, CI -2.62 to 0.45) and intervertebral discs (four trials, MD -0.98, CI -1.84 to 0.12), but the placebo effect is large and additional intervention effect size is small (<1 on an 11 point (0-10) Pain Scale). Longer-term effectiveness (>6 months) is uncertain.

CONCLUSIONS

RD of selected lumbosacral targets appears to have a small, short-term, positive effect for the management of patients with chronic back pain. However, the quality of evidence for the majority of outcomes is low or very low quality and there is still a degree of uncertainty, particularly around the duration of effect.

Radiofrequency denervation of the lumbar facet joints: guidelines for the RADICAL randomised controlled trial

Background and aim:

The RADICAL trial has been funded by the National Institute for Health Research (NIHR) to evaluate the clinical and cost-effectiveness of radiofrequency denervation (RFD) for low back pain. Recommendations have been published which aim to standardise selection of patients and RFD technique. However, it is important to ensure these recommendations are acceptable to clinicians within the context of the trial. The aim of this work was to develop standardised criteria for the trial entry and RFD technique for implementation within the RADICAL trial.

Methods:

Fourteen pain clinicians completed a survey, which involved reviewing the current recommendations and indicating whether they disagreed with any of the recommendations and if so why. Responses were collated and presented at a half-day workshop with 14 attendees. During the workshop, the National Low Back and Radicular Pain Pathway (NLBRPP) guidelines for patient selection and an article by Eldabe and colleagues presenting recommendations on the RFD technique were reviewed. Attendees discussed whether each component of the recommendations should be mandatory, mandatory with alteration or clarification or optional within the RADICAL trial.

Results:

Attendees agreed during the workshop that 5 of the 10 criteria for patient selection described in the NLBRPP should be mandatory within the RADICAL trial. Three were agreed as mandatory criteria but required further clarification, one of which involved defining a positive response to a diagnostic medial branch block as ⩾60% pain relief. Two criteria had optional components. After reviewing the recommendations on the RFD technique from Eldabe and colleagues, seven components were agreed as mandatory, three were mandatory with alterations and three were optional.

Conclusion:

When evaluating complex interventions, such as RFD, it is important to ensure agreement and clarity on the clinical protocol, so that the intervention can be reproduced, if found to be effective.

Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group

BACKGROUND

The past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial.

METHODS

After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4-5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached.

RESULTS

17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary).

CONCLUSIONS

Lumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Hypoxic stress enhances extension and branching of dorsal root ganglion neuronal outgrowth

It has been shown that painful intervertebral discs (IVDs) were associated with a deeper innervation. However, the effect of the disc's degenerative microenvironment on neuronal outgrowth remains largely unknown. The focus of this study was to determine the influence of hypoxia on dorsal root ganglion (DRG) neurite outgrowth. Toward this aim, the DRG-derived cell line ND7/23 was either directly subjected to 2% or 20% oxygen conditions or exposed to conditioned medium (CM) collected from IVDs cultured under 2% or 20% oxygen. Viability and outgrowth analysis were performed following 3 days of exposure. Results obtained with the cell line were further validated on cultures of rabbit spinal DRG explants and dissociated DRG neurons. Results showed that hypoxia significantly increased neurite outgrowth length in ND7/23 cells, which was also validated in DRG explant and primary cell culture, although hypoxia conditioned IVD did not significantly increase ND7/23 neurite outgrowth. While hypoxia dramatically decreased the outgrowth frequency in explant cultures, it significantly increased collateral sprouting of dissociated neurons. Importantly, the hypoxia-induced decrease of outgrowth frequency at the explant level was not due to inhibition of outgrowth branching but rather to neuronal necrosis. In summary, hypoxia in DRG promoted neurite sprouting, while neuronal necrosis may reduce the density of neuronal outgrowth at the tissue level. These findings may help to explain the deeper neo-innervation found in the painful disc tissue.

HIGHLIGHTS

Hypoxia promoted elongation and branching of neurite outgrowth at single cell level, but reduced outgrowth density at tissue level, possibly due to hypoxia-induced neuronal necrosis; these findings may help to explain the deeper neo-innervation found in clinically painful tissues.

Repeat procedures and prescription opioid use after lumbar medial branch nerve radiofrequency ablation in commercially insured patients

PURPOSE

Although the effectiveness of medial branch nerve radiofrequency ablation (RFA) for lumbosacral facet pain has been described, little is known regarding patterns of repeat RFA utilization and prescription opioid use afterward.

DESIGN

Retrospective cohort analysis.

PATIENT SAMPLE

Patients undergoing lumbosacral RFA in MarketScan from 2007 to 2016.

METHODS

The time until and number of staged RFAs (<180 days after initial RFA) and repeat RFAs (≥180 days after initial RFA), as well as opioid use at 90 and 180 days after RFA were assessed. Survival analyses were employed to estimate subsequent RFA rates, whereas subsequent RFA frequencies were estimated with inverse probability weighting. Repeated measures testing was performed comparing opioid use pre- and post-RFA.

RESULTS

Initial RFAs were identified in 44,936 patients. Staged RFAs were performed in 33.1% of patients. Repeat RFAs through 1, 3, and 7 years were performed for 14.6%, 33.5%, and 45.7% of patients, respectively. Within 3 years, 12.2% of patients underwent one repeat RFA, whereas 13.2% of patients underwent two or more. Post-RFA opioid use was examined in 128,310 patients, 32.2% of whom used opioids pre-RFA. By 180 days post-RFA, 8.1% of patients discontinued opioids and 6.7% started opioids (p<.001). Exclusively examining pre-RFA opioid users, 24.9% stopped filling opioid prescriptions 180 days after RFA.

CONCLUSIONS

This study delineates utilization rates of repeat RFA in the commerciall y insured population, with one-third undergoing repeat RFA within 3 years. Additionally, the present data indicate that lumbosacral RFA is associated with reduced filling of opioid prescriptions through 180 days.

Open facet joint denervation as an adjunct in patients undergoing posterior lumbar decompression for spinal stenosis-a single blinded randomized controlled trial

Background

Facet radiofrequency denervation is a prevalent procedure used to try and relieve back pain. Despite the increasing use of this treatment, its effectiveness has been questioned. In consideration of the conflicting reports in the literature, we sought to conduct a trial to study the short-term effect of facet denervation in patients undergoing lumbar laminectomy(s) to determine the short-term effect of adding facet denervation to patients undergoing lumbar laminectomy(s) where the anatomy was exposed, allowing an open technique to be used for the denervation.

Methods

Sixty patients with a diagnosis of degenerative lumbar spinal stenosis who complained of neurogenic claudication and back pain for at least 3 months were randomized to undergo a lumbar laminectomy(s) either with or without facet joint denervation. Pain and self-reported function using a 10 cm visual analogue scale (VAS) and the Roland-Morris Disability Questionnaire (RMDQ) were measured before surgery and at patients' 6-, 12- and 24-week follow-up clinic visit. Various parametric and non-parametric tests including the Chi-square, independent samples t-tests, the Mann Whitney U, Wilcoxon sign ranks, one-way ANOVA with a Bonferroni post hoc test were used to analyze the data. The RMDQ scores were analyzed between groups and within groups over time.

Results

No differences in pain or functional ability were seen between groups. Both groups significantly improved in both pain and function from baseline to follow up times.

Conclusions

Our findings do not support the addition of facet denervation for short-term treatment of back pain in patients undergoing lumbar laminectomy(s) for spinal stenosis within our study design.

Trends in lumbar radiofrequency ablation utilization from 2007 to 2016

BACKGROUND CONTEXT

Lumbar radiofrequency ablation (RFA) is an intervention used to treat facet-mediated chronic low back pain. In some studies with methods consistent with clinical practice guidelines, RFA results in improvements in pain and functional limitations. However, in other studies, RFA demonstrates limited benefit. Despite unanswered questions regarding efficacy of RFA, its use is widespread.

PURPOSE

To describe trends in the utilization and cost of lumbar RFA and lumbar facet injections.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

The sample was derived from the IBM/Watson MarketScan Commercial Claims and Encounters Databases from 2007 to 2016.

OUTCOME MEASURES

Longitudinal trends in the distribution and quantity of lumbar facet injections before lumbar RFA, corticosteroid administration during lumbar facet injections, progression to lumbar RFA after lumbar facet injections, lumbar RFA utilization, and costs of these interventions.

METHODS

Two primary cohorts were identified from patients who received lumbar RFA or lumbar facet injection procedures. Utilization rates per 100,000 enrollees were determined for both cohorts. The mean, median, and interquartile ranges of the number of facets targeted and costs per procedure were calculated by year and laterality, as well as overall. Costs in 2018 dollars were estimated by summing gross payment totals from patients and insurance plans. This study was supported by funds from the NIH, and has no conflict of interest associated biases.

RESULTS

From 2007 to 2016, lumbar RFA sessions performed per 100,000 enrollees per year increased from 49 to 113, a 130.6% overall increase (9.7% annually). Lumbar facet injection use increased from 201 to 251 sessions per 100,000 enrollees, a 24.9% overall increase (2.5% annually). In the year after a lumbar facet injection, 26.7% of patients received lumbar RFA; 28.6% received another injection but not RFA; and 44.7% received neither. The number of patients receiving two lumbar facet injection procedures prior to lumbar RFA grew from 51.1% in 2010 to 58.8% in 2016. For lumbar RFA, the cost per 100,000 enrollees went from $94,570 in 2007 to $266,680 in 2016, a 12.2% annual increase. For lumbar facet injections, the cost per 100,000 enrollees went from $257,280 in 2007 to $396,580 in 2016, a 4.9% annual increase.

CONCLUSIONS

This analysis showed consistent growth in both the frequency and procedure cost of lumbar RFA and facet injections among a large, national, commercially insured population from 2007 to 2016.

Current Concepts in Intradiscal Percutaneous Minimally Invasive Procedures for Chronic Low Back Pain

Study Design:

A systemic review of thermal annular procedures (TAPs) and percutaneous disk decompression procedures (PDDPs) for the treatment of discogenic chronic low back pain (CLBP) was conducted.

Objective:

The objective of this review is to evaluate and to compare the effectiveness of TAPs and PDDPs in treating discogenic CLBP and to assess the frequency of complications associated with those procedures.

Materials and Methods:

English-language journal articles were identified through computerized searches of the PubMed database and bibliographies of identified articles and review papers. Articles were selected for inclusion if percutaneous minimally invasive procedures were the treatment options for patients with CLBP and if follow-up outcome data included evaluations of back pain severity, functional improvement, and/or incidence of complications. For this review, 27 studies were included.

Results:

Intradiscal electrothermal therapy (IDET) procedure in properly selected patients may eliminate or delay the need for surgical intervention for an extended period, whereas few adverse effects have been reported. In contrast to IDET, there is far less literature on the effectiveness of radiofrequency annuloplasty and intradiscal biacuplasty procedures. Nucleoplasty is a potentially effective treatment option for patients with contained disc herniation, while the procedure is well tolerated. Increased success rates have been found for percutaneous laser disc decompression and automated percutaneous lumbar discectomy in strictly selected patients.

Conclusions:

These procedures can be effective and may obviate the need for surgery completely. Further prospective randomized sham-controlled trials with higher quality of evidence are necessary to confirm the efficacy of these procedures.

Unique aspects of clinical trials of invasive therapies for chronic pain

Nearly all who review the literature conclude that the role of invasive procedures to treat chronic pain is poorly characterized because of the lack of “definitive” studies. The overt nature of invasive treatments, along with the risks, technical skills, and costs involved create challenges to study them. However, these challenges do not completely preclude evaluating invasive procedure effectiveness and safety using well-designed methods. This article reviews the challenges of studying outcomes of invasive therapies to treat pain and discuss possible solutions. Although the following discussion can apply to most invasive therapies to treat chronic pain, it is beyond the scope of the article to individually cover every invasive therapy used. Therefore, most of the examples focus on injection therapies to treat spine pain, spinal cord stimulation, and intrathecal drug therapies.

Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: With facet interventions under scrutiny, the authors' objectives were to determine the effectiveness of different lumbar facet blocks and their ability to predict radiofrequency ablation outcomes.

METHODS

A total of 229 participants were randomized in a 2:2:1 ratio to receive intraarticular facet injections with bupivacaine and steroid, medial branch blocks, or saline. Those with a positive 1-month outcome (a 2-point or more reduction in average pain score) and score higher than 3 (positive satisfaction) on a 5-point satisfaction scale were followed up to 6 months. Participants in the intraarticular and medial branch block groups with a positive diagnostic block (50% or more relief) who experienced a negative outcome proceeded to the second phase and underwent radiofrequency ablation, while all saline group individuals underwent ablation. Coprimary outcome measures were average reduction in numerical rating scale pain score 1 month after the facet or saline blocks, and average numerical rating scale pain score 3 months after ablation.

RESULTS

Mean reduction in average numerical rating scale pain score at 1 month was 0.7 ± 1.6 in the intraarticular group, 0.7 ± 1.8 in the medial branch block group, and 0.7 ± 1.5 in the placebo group; P = 0.993. The proportions of positive blocks were higher in the intraarticular (54%) and medial branch (55%) groups than in the placebo group (30%; P = 0.01). Radiofrequency ablation was performed on 135 patients (45, 48, and 42 patients from the intraarticular, medial branch, and saline groups, respectively). The average numerical rating scale pain score at 3 months was 3.0 ± 2.0 in the intraarticular, 3.2 ± 2.5 in the medial branch, and 3.5 ± 1.9 in the control group (P = 0.493). At 3 months, the proportions of positive responders in the intraarticular, medial branch block, and placebo groups were 51%, 56%, and 24% for the intraarticular, medial branch, and placebo groups, respectively (P = 0.005).

CONCLUSIONS

This study establishes that facet blocks are not therapeutic. The higher responder rates in the treatment groups suggest a hypothesis that facet blocks might provide prognostic value before radiofrequency ablation.

What low back pain is and why we need to pay attention

Low back pain is a very common symptom. It occurs in high-income, middle-income, and low-income countries and all age groups from children to the elderly population. Globally, years lived with disability caused by low back pain increased by 54% between 1990 and 2015, mainly because of population increase and ageing, with the biggest increase seen in low-income and middle-income countries. Low back pain is now the leading cause of disability worldwide. For nearly all people with low back pain, it is not possible to identify a specific nociceptive cause. Only a small proportion of people have a well understood pathological cause-eg, a vertebral fracture, malignancy, or infection. People with physically demanding jobs, physical and mental comorbidities, smokers, and obese individuals are at greatest risk of reporting low back pain. Disabling low back pain is over-represented among people with low socioeconomic status. Most people with new episodes of low back pain recover quickly; however, recurrence is common and in a small proportion of people, low back pain becomes persistent and disabling. Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain. Increasing evidence shows that central pain-modulating mechanisms and pain cognitions have important roles in the development of persistent disabling low back pain. Cost, health-care use, and disability from low back pain vary substantially between countries and are influenced by local culture and social systems, as well as by beliefs about cause and effect. Disability and costs attributed to low back pain are projected to increase in coming decades, in particular in low-income and middle-income countries, where health and other systems are often fragile and not equipped to cope with this growing burden. Intensified research efforts and global initiatives are clearly needed to address the burden of low back pain as a public health problem.

Pulse-dose radiofrequency treatment in pain management-initial experience

Radiofrequency procedures have been used for treating various chronic pain conditions for decades. These minimally invasive percutaneous treatments employ an alternating electrical current with oscillating radiofrequency wavelengths to eliminate or alter pain signals from the targeted site. The aim of the continuous radiofrequency procedure is to increase the temperature sufficiently to create an irreversible thermal lesion on nerve fibres and thus permanently interrupt pain signals. The pulsed radiofrequency procedure utilises short pulses of radiofrequency current with intervals of longer pauses to avert a temperature increase to the level of permanent tissue damage. The goal of these pulses is to alter the processing of pain signals, but to avoid relevant structural damage to nerve fibres, as seen in the continuous radiofrequency procedure. The pulse-dose radiofrequency procedure is a technical improvement of the pulsed radiofrequency technique in which the delivery mode of the current is adapted. During the pulse-dose radiofrequency procedure thermal damage is avoided. In addition, the amplitude and width of the consecutive pulses are kept the same. The method ensures that each delivered pulse keeps the same characteristics and therefore the dose is similar between patients. The current review outlines the pulse-dose radiofrequency procedure and presents our institution's chronic pain management studies.

Core outcome measurement instruments for clinical trials in nonspecific low back pain

To standardize outcome reporting in clinical trials of patients with nonspecific low back pain, an international multidisciplinary panel recommended physical functioning, pain intensity, and health-related quality of life (HRQoL) as core outcome domains. Given the lack of a consensus on measurement instruments for these 3 domains in patients with low back pain, this study aimed to generate such consensus. The measurement properties of 17 patient-reported outcome measures for physical functioning, 3 for pain intensity, and 5 for HRQoL were appraised in 3 systematic reviews following the COSMIN methodology. Researchers, clinicians, and patients (n = 207) were invited in a 2-round Delphi survey to generate consensus (≥67% agreement among participants) on which instruments to endorse. Response rates were 44% and 41%, respectively. In round 1, consensus was achieved on the Oswestry Disability Index version 2.1a for physical functioning (78% agreement) and the Numeric Rating Scale (NRS) for pain intensity (75% agreement). No consensus was achieved on any HRQoL instrument, although the Short Form 12 (SF12) approached the consensus threshold (64% agreement). In round 2, a consensus was reached on an NRS version with a 1-week recall period (96% agreement). Various participants requested 1 free-to-use instrument per domain. Considering all issues together, recommendations on core instruments were formulated: Oswestry Disability Index version 2.1a or 24-item Roland-Morris Disability Questionnaire for physical functioning, NRS for pain intensity, and SF12 or 10-item PROMIS Global Health form for HRQoL. Further studies need to fill the evidence gaps on the measurement properties of these and other instruments.

Facet joint injections for people with persistent non-specific low back pain (Facet Injection Study): a feasibility study for a randomised controlled trial

BACKGROUND

The National Institute for Health and Care Excellence (NICE) 2009 guidelines for persistent low back pain (LBP) do not recommend the injection of therapeutic substances into the back as a treatment for LBP because of the absence of evidence for their effectiveness. This feasibility study aimed to provide a stable platform that could be used to evaluate a randomised controlled trial (RCT) on the clinical effectiveness and cost-effectiveness of intra-articular facet joint injections (FJIs) when added to normal care.

OBJECTIVES

To explore the feasibility of running a RCT to test the hypothesis that, for people with suspected facet joint back pain, adding the option of intra-articular FJIs (local anaesthetic and corticosteroids) to best usual non-invasive care is clinically effective and cost-effective.

DESIGN

The trial was a mixed design. The RCT pilot protocol development involved literature reviews and a consensus conference followed by a randomised pilot study with an embedded mixed-methods process evaluation.

SETTING

Five NHS acute trusts in England.

PARTICIPANTS

Participants were patients aged ≥ 18 years with moderately troublesome LBP present (> 6 months), who had failed previous conservative treatment and who had suspected facet joint pain. The study aimed to recruit 150 participants (approximately 30 per site). Participants were randomised sequentially by a remote service to FJIs combined with 'best usual care' (BUC) or BUC alone.

INTERVENTIONS

All participants were to receive six sessions of a bespoke BUC rehabilitation package. Those randomised into the intervention arm were, in addition, given FJIs with local anaesthetic and steroids (at up to six injection sites). Randomisation occurred at the end of the first BUC session.

MAIN OUTCOME MEASURES

Process and clinical outcomes. Clinical outcomes included a measurement of level of pain on a scale from 0 to 10, which was collected daily and then weekly via text messaging (or through a written diary). Questionnaire follow-up was at 3 months.

RESULTS

Fifty-two stakeholders attended the consensus meeting. Agreement informed several statistical questions and three design considerations: diagnosis, the process of FJI and the BUC package and informing the design for the randomised pilot study. Recruitment started on 26 June 2015 and was terminated by the funder (as a result of poor recruitment) on 11 December 2015. In total, 26 participants were randomised. Process data illuminate some of the reasons for recruitment problems but also show that trial processes after enrolment ran smoothly. No between-group analysis was carried out. All pain-related outcomes show the expected improvement between baseline and follow-up. The mean total cost of the overall treatment package (injection £419.22 and BUC £264.00) was estimated at £683.22 per participant. This is similar to a NHS tariff cost for a course of FJIs of £686.84.

LIMITATIONS

Poor recruitment was a limiting factor.

CONCLUSIONS

This feasibility study achieved consensus on the main challenges in a trial of FJIs for people with persistent non-specific low back pain.

FUTURE WORK

Further work is needed to test recruitment from alternative clinical situations.

TRIAL REGISTRATION

EudraCT 2014-000682-50 and Current Controlled Trials ISRCTN93184143.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 30. See the NIHR Journals Library website for further project information.

New Therapy for Refractory Chronic Mechanical Low Back Pain-Restorative Neurostimulation to Activate the Lumbar Multifidus: One Year Results of a Prospective Multicenter Clinical Trial

Objectives

The purpose of the international multicenter prospective single arm clinical trial was to evaluate restorative neurostimulation eliciting episodic contraction of the lumbar multifidus for treatment of chronic mechanical low back pain (CMLBP) in patients who have failed conventional therapy and are not candidates for surgery or spinal cord stimulation (SCS).

Materials and Methods

Fifty‐three subjects were implanted with a neurostimulator (ReActiv8, Mainstay Medical Limited, Dublin, Ireland). Leads were positioned bilaterally with electrodes close to the medial branch of the L2 dorsal ramus nerve. The primary outcome measure was low back pain evaluated on a 10‐Point Numerical Rating Scale (NRS). Responders were defined as subjects with an improvement of at least the Minimal Clinically Important Difference (MCID) of ≥2‐point in low back pain NRS without a clinically meaningful increase in LBP medications at 90 days. Secondary outcome measures included Oswestry Disability Index (ODI) and Quality of Life (QoL; EQ‐5D).

Results

For 53 subjects with an average duration of CLBP of 14 years and average NRS of 7 and for whom no other therapies had provided satisfactory pain relief, the responder rate was 58%. The percentage of subjects at 90 days, six months, and one year with ≥MCID improvement in single day NRS was 63%, 61%, and 57%, respectively. Percentage of subjects with ≥MCID improvement in ODI was 52%, 57%, and 60% while those with ≥MCID improvement in EQ‐5D was 88%, 82%, and 81%. There were no unanticipated adverse events (AEs) or serious AEs related to the device, procedure, or therapy. The initial surgical approach led to a risk of lead fracture, which was mitigated by a modification to the surgical approach.

Conclusions

Electrical stimulation to elicit episodic lumbar multifidus contraction is a new treatment option for CMLBP. Results demonstrate clinically important, statistically significant, and lasting improvement in pain, disability, and QoL.

The efficacy of conventional radiofrequency denervation in patients with chronic low back pain originating from the facet joints: a meta-analysis of randomized controlled trials

BACKGROUND CONTEXT

Radiofrequency denervation is commonly used for the treatment of chronic facet joint pain that has been refractory to more conservative treatments, although the evidence supporting this treatment has been controversial.

PURPOSE

We aimed to elucidate the precise effects of radiofrequency denervation in patients with low back pain originating from the facet joints relative to those obtained using control treatments, with particular attention to consistency in the denervation protocol.

STUDY DESIGN/SETTING

A meta-analysis of randomized controlled trials was carried out.

PATIENT SAMPLE

Adult patients undergoing radiofrequency denervation or control treatments (sham or epidural block) for facet joint disease of the lumbar spine comprised the patient sample.

OUTCOME MEASURES

Visual analog scale (VAS) pain scores were measured and stratified by response of diagnostic block procedures.

METHOD

We searched PubMed, Embase, Web of Science, and the Cochrane Database for randomized controlled trials regarding radiofrequency denervation and control treatments for back pain. Changes in VAS pain scores of the radiofrequency group were compared with those of the control group as well as the minimal clinically important difference (MCID) for back pain VAS. Meta-regression model was developed to evaluate the effect of radiofrequency treatment according to responses of diagnostic block while controlling for other variables. We then calculated mean differences and 95% confidence intervals (CIs) using random-effects models.

RESULTS

We included data from seven trials involving 454 patients who had undergone radiofrequency denervation (231 patients) and control treatments such as sham or epidural block procedures (223 patients). The radiofrequency group exhibited significantly greater improvements in back pain score when compared with the control group for 1-year follow-up. Although the average improvement in VAS scores exceeded the MCID, the lower limit of the 95% CI encompassed the MCID. A subgroup of patients who responded very well to diagnostic block procedures demonstrated significant improvements in back pain relative to the control group at all times. When placed into our meta-regression model, the response to diagnostic block procedure was responsible for a statistically significant portion of treatment effect. Studies published over the last two decades revealed that radiofrequency denervation reduced back pain significantly in patients with facet joint disease compared with the MCID and control treatments.

CONCLUSIONS

Conventional radiofrequency denervation resulted in significant reductions in low back pain originating from the facet joints in patients showing the best response to diagnostic block over the first 12 months when compared with sham procedures or epidural nerve blocks.

Effect of Radiofrequency Denervation on Pain Intensity Among Patients With Chronic Low Back Pain: The Mint Randomized Clinical Trials

IMPORTANCE

Radiofrequency denervation is a commonly used treatment for chronic low back pain, but high-quality evidence for its effectiveness is lacking.

OBJECTIVE

To evaluate the effectiveness of radiofrequency denervation added to a standardized exercise program for patients with chronic low back pain.

DESIGN, SETTING, AND PARTICIPANTS

Three pragmatic multicenter, nonblinded randomized clinical trials on the effectiveness of minimal interventional treatments for participants with chronic low back pain (Mint study) were conducted in 16 multidisciplinary pain clinics in the Netherlands. Eligible participants were included between January 1, 2013, and October 24, 2014, and had chronic low back pain, a positive diagnostic block at the facet joints (facet joint trial, 251 participants), sacroiliac joints (sacroiliac joint trial, 228 participants), or a combination of facet joints, sacroiliac joints, or intervertebral disks (combination trial, 202 participants) and were unresponsive to conservative care.

INTERVENTIONS

All participants received a 3-month standardized exercise program and psychological support if needed. Participants in the intervention group received radiofrequency denervation as well. This is usually a 1-time procedure, but the maximum number of treatments in the trial was 3.

MAIN OUTCOMES AND MEASURES

The primary outcome was pain intensity (numeric rating scale, 0-10; whereby 0 indicated no pain and 10 indicated worst pain imaginable) measured 3 months after the intervention. The prespecified minimal clinically important difference was defined as 2 points or more. Final follow-up was at 12 months, ending October 2015.

RESULTS

Among 681 participants who were randomized (mean age, 52.2 years; 421 women [61.8%], mean baseline pain intensity, 7.1), 599 (88%) completed the 3-month follow-up, and 521 (77%) completed the 12-month follow-up. The mean difference in pain intensity between the radiofrequency denervation and control groups at 3 months was -0.18 (95% CI, -0.76 to 0.40) in the facet joint trial; -0.71 (95% CI, -1.35 to -0.06) in the sacroiliac joint trial; and -0.99 (95% CI, -1.73 to -0.25) in the combination trial.

CONCLUSIONS AND RELEVANCE

In 3 randomized clinical trials of participants with chronic low back pain originating in the facet joints, sacroiliac joints, or a combination of facet joints, sacroiliac joints, or intervertebral disks, radiofrequency denervation combined with a standardized exercise program resulted in either no improvement or no clinically important improvement in chronic low back pain compared with a standardized exercise program alone. The findings do not support the use of radiofrequency denervation to treat chronic low back pain from these sources.

TRIAL REGISTRATION

trialregister.nl Identifier: NTR3531.

Providing chronic pain management in the "Fifth Vital Sign" Era: Historical and treatment perspectives on a modern-day medical dilemma

BACKGROUND

Over 100 million Americans are living with chronic pain, and pain is the most common reason that patients seek medical attention. Despite the prevalence of pain, the practice of pain management and the scientific discipline of pain research are relatively new fields compared to the rest of medicine - contributing to a twenty-first century dilemma for health care providers asked to relieve suffering in the "Fifth Vital Sign" era.

METHODS

This manuscript provides a narrative review of the basic mechanisms of chronic pain and history of chronic pain management in the United States - including the various regulatory, health system and provider factors that contributed to the decline of multidisciplinary pain treatment in favor of the predominant opioid treatment strategy seen today. Multiple non-opioid pain treatment strategies are then outlined. The manuscript concludes with three key questions to help guide future research at the intersection of pain and addiction.

CONCLUSIONS

The assessment and treatment of chronic pain will continue to be one of the most common functions of a health care provider. To move beyond an over reliance on opioid medications, the addiction and pain research communities must unite with chronic pain patients to increase the evidence base supporting non-opioid analgesic strategies.

Non-specific low back pain

Non-specific low back pain affects people of all ages and is a leading contributor to disease burden worldwide. Management guidelines endorse triage to identify the rare cases of low back pain that are caused by medically serious pathology, and so require diagnostic work-up or specialist referral, or both. Because non-specific low back pain does not have a known pathoanatomical cause, treatment focuses on reducing pain and its consequences. Management consists of education and reassurance, analgesic medicines, non-pharmacological therapies, and timely review. The clinical course of low back pain is often favourable, thus many patients require little if any formal medical care. Two treatment strategies are currently used, a stepped approach beginning with more simple care that is progressed if the patient does not respond, and the use of simple risk prediction methods to individualise the amount and type of care provided. The overuse of imaging, opioids, and surgery remains a widespread problem.

Pulsed radiofrequency in clinical practice - A retrospective analysis of 238 patients with chronic non-cancer pain treated at an academic tertiary pain centre

BACKGROUND AND AIMS

Pulsed radiofrequency is a non-neurodestructive invasive pain treatment which, in contrast to conventional continuous radiofrequency treatment, does not entail nerve tissue destruction. The aim of this study was to retrospectively analyse the short-term benefits of a broad use of pulsed radiofrequency in clinical practice.

METHODS

The medical records of all patients treated with pulsed radiofrequency, or who received a diagnostic test block with a local anaesthetic in view of such a treatment, were retrospectively analysed. The patients had been referred to a tertiary pain centre in Sweden. The treatment effect one month after pulsed radiofrequency was retrospectively graded as follows, based on the wordings of the medical records: major improvement; minor improvement; no change; or worsened.

RESULTS

A total of 238 patients received 587 interventions from 2009 to 2014. Chronic low back pain (CLBP) was by far the most common treatment indication (57% of patients), followed by CLBP with sciatica (9%). The age at first pulsed radiofrequency was 55 (15-94) years (mean, range), and 65% were female. Thirty-six patients (15%) underwent only a diagnostic test block using a local anaesthetic, i.e., the test block did not lead to treatment with pulsed radiofrequency. A total of 445 pulsed radiofrequency interventions were performed on 202 patients. Dichotomizing data into responders (i.e., minor or major improvement) and non-responders (i.e., worsened or no change), we found that, out of 63 responders to a median branch diagnostic test block (either at the cervical or lumbar level), 33 were responders to the first following median branch pulsed radiofrequency. Hence the positive predictive value of a median branch test block was 52%. In 127 patients, the lumbar level was targeted for median branch pulsed radiofrequency because of clinically suspected lumbar facetogenic pain. Looking at the first treatment, 30% experienced major improvement after 1 month, 16% minor improvement, 36% no change, 5% a worsened situation, and the effect was not assessable in 13% of patients. Lone dorsal root ganglion L2-treatment for suspected discogenic lumbar pain was done on 39 patients and, after one month, the effect was not assessable in 17% of patients, 14% had major improvement, 14% minor improvement, and 55% had no change. In 40 patients, a dorsal root ganglion or a peripheral nerve was targeted because of a non-axial chronic pain condition. There was a plethora of indications, but the most common was by far related to some form of neuropathic pain (52% of interventions, mainly because of neuralgia), followed by chronic nociceptive shoulder pain (8% of interventions).

CONCLUSIONS

This study shows that, after one month, the effect size of a broad and indiscriminate clinical use of pulsed radiofrequency is rather small.

IMPLICATIONS

The clinical effectiveness of pulsed radiofrequency has to be investigated further in carefully selected and more homogenous patient groups, in order to define effective treatment niches for this nondestructive invasive treatment method.