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The technique of lumbar medial branch radiofrequency neurotomy for facet joint pain has an intriguing history involving a diverse timeline of medical specialists. This paper aims to chart the pathway that led to its invention and the series of modifications and refinements that have led to modern practice. The story begins with the treatment of World War I soldiers by Nesfield, who used scalpels to cut "trapped" nerves. Inspired by Nesfield's treatment, Rees developed the "percutaneous rhizolysis" technique in 1960. Shealy was the first to use radiofrequency electrodes for denervation of the facet joints, introducing his technique in 1971. Several radiofrequency electrode developments came about from collaborations with Cosman medical device entrepreneurs during the 1970s, including the Shealy Rhizolysis Kit, the Ray Rhizotomy Electrode, and the Sluijter-Mehta Kit. Subsequent dissections of Rees' technique and modification of Shealy's procedure by Bogduk saw the development of "percutaneous lumbar medial branch neurotomy" in 1980 by Bogduk and Long. Bogduk continued to contribute significantly to validation, refinement and acceptance of the technique. In 1998, the technique of pulsed radiofrequency was invented by Sluijter, Cosman, Rittman and van Kleef. Subsequent innovations have consisted of cooled radiofrequency neurotomy, multi-tined cannulae, endoscopic systems, and alternative denervation targets, such as the facet joint capsule. As we pass the first 100 years of the story, we believe there are more chapters to be written on this fascinating subject., Competing Interests: MR provides unpaid consulting for Abbott, Boston Scientific, Mainstay Medical, Medtronic, Nevro, Presidio Medical, Saluda and Stimwave, conducts sponsored research activities for Boston Scientific, Mainstay Medical, Medtronic, Nevro, Presidio Medical and Saluda, and is a stockholder in Freedom Neuro, Lungpacer, Precise Light Surgical and SPR Therapeutics. RW provides consulting for Abbott and reports patents US10716618B2 and US10736688B2 issued to Stratus Medical, LLC. CG provides consulting for Abbott, Iliad Lifesciences, Medtronic and Saluda, conducts research activities for Mainstay Medical and Sollis Therapeutics, reports personal fees from Medtronic, Abbott, Eli Lilly, Saluda, Persica Pharmaceuticals, Iliad Lifesciences, and Expert Witness, and research support paid directly to their institution by Mainstay Medical, outside the submitted work. MR, RW and CG declare no other potential conflicts of interest for this work and declare no consulting, payments received, or other conflicts of interest with any of the companies whose technologies are mentioned in this manuscript. DS has no conflicts of interest for this work to declare., (© 2021 Russo et al.)

Objectives: The purpose of the ongoing follow-up of ReActiv8-A clinical trial is to document the longitudinal benefits of episodic stimulation of the dorsal ramus medial branch and consequent contraction of the lumbar multifidus in patients with refractory mechanical chronic low back pain (CLBP). We report the four-year outcomes of this trial., Materials and Methods: ReActiv8-A is a prospective, single-arm trial performed at nine sites in the United Kingdom, Belgium, and Australia. Eligible patients had disabling CLBP (low back pain Numeric Rating Scale [NRS] ≥6; Oswestry Disability Index [ODI] ≥25), no indications for spine surgery or spinal cord stimulation, and failed conventional management including at least physical therapy and medications for low back pain. Fourteen days postimplantation, stimulation parameters were programmed to elicit strong, smooth contractions of the multifidus, and participants were given instructions to activate the device for 30-min stimulation-sessions twice daily. Annual follow-up through four years included collection of NRS, ODI, and European Quality of Life Score on Five Dimensions (EQ-5D). Background on mechanisms, trial design, and one-year outcomes were previously described., Results: At baseline (N = 53) (mean ± SD) age was 44 ± 10 years; duration of back pain was 14 ± 11 years, NRS was 6.8 ± 0.8, ODI 44.9 ± 10.1, and EQ-5D 0.434 ± 0.185. Mean improvements from baseline were statistically significant (p < 0.001) and clinically meaningful for all follow-ups. Patients completing year 4 follow-up, reported mean (±standard error of the mean) NRS: 3.2 ± 0.4, ODI: 23.0 ± 3.2, and EQ-5D: 0.721 ± 0.035. Moreover, 73% of participants had a clinically meaningful improvement of ≥2 points on NRS, 76% of ≥10 points on ODI, and 62.5% had a clinically meaningful improvement in both NRS and ODI and 97% were (very) satisfied with treatment., Conclusions: In participants with disabling intractable CLBP who receive long-term restorative neurostimulation, treatment satisfaction remains high and improvements in pain, disability, and quality-of-life are clinically meaningful and durable through four years., (© 2021 The Authors. Neuromodulation: Technology at the Neural Interface published by Wiley Periodicals LLC on behalf of International Neuromodulation Society.)

Introduction: Chronic pain is a major public health concern, as is the associated use of opioid medications, highlighting the importance of alternative treatments, such as spinal cord stimulation (SCS). Here, we present the final 24-month results of the Avalon study, which investigated the use of the first closed-loop SCS system in patients with chronic pain. The system measures the evoked compound action potentials (ECAPs) elicited by each stimulus pulse and drives a feedback loop to maintain the ECAP amplitude near constant., Methods: Fifty patients were implanted with the Evoke system (Saluda Medical) and followed over 24-months. Pain, quality of life (QOL), function, sleep, and medication use were collected at baseline and each scheduled visit. ECAP amplitudes and programming adjustments were also monitored., Results: At 24 months, responder rates (≥ 50% pain reduction) and high responder rates (≥ 80% pain reduction) for overall pain were 89.5% and 68.4%, respectively, the latter up from 42.2% at 3 months. Significant improvements from baseline were observed in QOL, function, and sleep over the 24 months, including ≥ 80% experiencing a minimally important difference in QOL and > 50% experiencing a clinically significant improvement in sleep. At 24 months, 82.8% of patients with baseline opioid use eliminated or reduced their opioid intake. Over the course of the study, reprogramming need fell to an average of less than once a year., Conclusion: Over a 24-month period, the Evoke closed-loop SCS maintained its therapeutic efficacy despite a marked reduction in opioid use and steady decrease in the need for reprogramming., (© 2021 The Authors. Pain Practice published by Wiley Periodicals LLC on behalf of World Institute of Pain.)

Background: Spinal cord stimulation (SCS) activates the dorsal column fibers using electrical stimuli. Current SCS systems function in fixed-output mode, delivering the same stimulus regardless of spinal cord (SC) activation., Objective: To present long-term outcomes of a novel closed-loop SCS system that aims to maintain the SC activation near a set target level and within a therapeutic window for each patient. SC activation is measured through the evoked compound action potential (ECAP) generated by each stimulus pulse., Methods: Fifty patients with lower back and/or leg pain who were successfully trialed received a permanent system (Evoke; Saluda Medical, Sydney, Australia). Ratings of pain (visual analog scale), quality of life, function, sleep, and medication use were collected at baseline and at each visit. SC activation levels were reported in summary statistics. The therapeutic window for each individual patient was defined as the range of ECAP amplitudes between sensation threshold and uncomfortably strong stimulation., Results: At 12 mo, the proportion of patients with ≥50% relief was 76.9% (back), 79.3% (leg), and 81.4% (overall), and the proportion with ≥80% pain relief was 56.4% (back), 58.6% (leg), and 53.5% (overall). Patients spent a median of 84.9% of their time with stimulation in their therapeutic window, and 68.8% (22/32) eliminated or reduced their opioid intake. Statistically significant improvements in secondary outcomes were observed., Conclusion: The majority of patients experienced more than 80% pain relief with stable SC activation, as measured by ECAP amplitude at 12 mo, providing evidence for the long-term effectiveness of the Evoke closed-loop SCS system., (© Congress of Neurological Surgeons 2020.)

Objective: To identify relationships between clinical assessments of chronic pain to enable the generation of a multivariate model to predict patient satisfaction with spinal cord stimulation (SCS) treatment., Materials and Methods: Data from an exploratory clinical trial of sub-perception SCS (SPSCS) were reviewed. Forty-seven subjects tested multiple SPSCS programs for three to four days each. At the end of each program period, subjects recorded pain intensity, patient satisfaction with treatment (PSWT), modified patient global impression of change, and physical activity tolerance times. Twelve outcome variables were evaluated. Pearson's correlation coefficient was used to assess pair-wise correlations. Multigenerational mixed effects modeling was performed to create a model to best explain relationships between those variables., Results: A final model was generated that predicted PSWT using evening pain intensity (EPI) and the interaction between EPI and walking tolerance time. The mixed effects model allows for visualization of the interactions between EPI, walking tolerance time, and patient satisfaction with SCS., Conclusions: Patient-centered outcomes are desirable when evaluating complex multidimensional health impairments but accurately predicting patient satisfaction with treatment remains a challenge. Understanding the variables that predict (either by causation or association) satisfaction would be useful for clinicians. The results of this study suggest that a composite measure of activity tolerance (i.e., walking tolerance) and pain intensity can predict patient satisfaction with SCS therapy. This study highlights the utility of composite outcomes metrics in evaluating the benefits of SCS for chronic low back and leg pain., (© 2019 International Neuromodulation Society.)

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., (© 2017 The Authors. Neuromodulation: Technology at the Neural Interface published by Wiley Periodicals, Inc. on behalf of International Neuromodulation Society.)

Objectives: Conventional spinal cord stimulation (SCS) delivers a fixed-input of energy into the dorsal column. Physiologic effects such as heartbeat, respiration, spinal cord movement, and history of stimulation can cause both the perceived intensity and recruitment of stimulation to increase or decrease, with clinical consequences. A new SCS system controls stimulation dose by measuring the recruitment of fibers in the dorsal column and by using the amplitude of the evoked compound action potentials (ECAPs) to maintain stimulation within an individualized therapeutic range. Safety and efficacy of this closed-loop system was evaluated through six-month postimplantation., Materials and Methods: Chronic pain subjects with back and/or leg pain who were successfully trialed received a permanent system (Evoke; Saluda Medical, Sydney, Australia). Ratings of pain (100-mm visual analogue scale [VAS] and Brief Pain Instrument [BPI]), quality of life (EuroQol instrument [EQ-5D-5L]), function (Oswestry Disability Index [ODI]), and sleep (Pittsburgh Sleep Quality Index [PSQI]) were collected at baseline and repeated three and six months after implantation., Results: Fifty-one subjects underwent a trial procedure; permanent implants were placed in 36 subjects. The proportion of subjects with ≥50% relief was 92.6% (back) and 91.3% (leg) at three months, and 85.7% (back) and 82.6% (leg) at six months. The proportion with ≥80% pain relief was 70.4% (back) and 56.5% (leg) at three months, and 64.3% (back) and 60.9% (leg) at six months. Statistically significant improvements in mean BPI, EQ-5D-5L, ODI, and PSQI were also observed at both time points., Conclusions: The majority of subjects experienced profound pain relief at three and six months, providing preliminary evidence for the effectiveness of the closed-loop SCS system. The exact mechanism of action for these outcomes is still being explored, although one likely hypothesis holds that ECAP feedback control may minimize recruitment of Aβ nociceptors and Aδ fibers during daily use of SCS., (© 2017 International Neuromodulation Society.)

Objectives: Chronic low back pain (CLBP) is the most prevalent of the painful musculoskeletal conditions. CLBP is a heterogeneous condition with many causes and diagnoses, but there are few established therapies with strong evidence of effectiveness (or cost effectiveness). CLBP for which it is not possible to identify any specific cause is often referred to as non-specific chronic LBP (NSCLBP). One type of NSCLBP is continuing and recurrent primarily nociceptive CLBP due to vertebral joint overload subsequent to functional instability of the lumbar spine. This condition may occur due to disruption of the motor control system to the key stabilizing muscles in the lumbar spine, particularly the lumbar multifidus muscle (MF)., Methods: This review presents the evidence for MF involvement in CLBP, mechanisms of action of disruption of control of the MF, and options for restoring control of the MF as a treatment for NSCLBP., Results: Imaging assessment of motor control dysfunction of the MF in individual patients is fraught with difficulty. MRI or ultrasound imaging techniques, while reliable, have limited diagnostic or predictive utility. For some patients, restoration of motor control to the MF with specific exercises can be effective, but population results are not persuasive since most patients are unable to voluntarily contract the MF and may be inhibited from doing so due to arthrogenic muscle inhibition., Conclusions: Targeting MF control with restorative neurostimulation promises a new treatment option., (© 2017 The Authors. Neuromodulation: Technology at the Neural Interface published by Wiley Periodicals, Inc. on behalf of International Neuromodulation Society.)

Objective: The aim of this study was to compare the efficacy and safety of a new oromucosal ibuprofen form, ibuprofen 25 mg lozenge, in single and repeat dosing for up to 4 days, to the matched placebo, in the treatment of acute sore throat pain in adults., Methods: In this randomised, double-blind, placebo-controlled trial, adult patients with non-streptococcal sore throat and signs of moderate-to-severe associated pain (≥5 on the objective Tonsillo-Pharyngitis Assessment 21-point scale and ≥60 mm on the subjective 0-100 mm visual analogue Sore Throat Pain Intensity Scale [STPIS]) were assigned ibuprofen 25 mg (n=194) or matching placebo (n=191) lozenge treatment. Efficacy was assessed (at the investigating centre up to 2 hours after first dosing, then on an ambulatory basis) by parameters derived from patient's scores on scales of pain relief, pain intensity, and global efficacy assessment. The primary efficacy end-point was the time-weighted TOTal PAin Relief (TOTPAR) over 2 hours after first dosing using the Sore Throat Relief Scale (STRS). Safety and local tolerability were assessed., Results: Ibuprofen 25 mg was superior to placebo on numerous pain relief parameters; TOTPAR was significantly higher with ibuprofen 25 mg over 2 hours after first dosing (P<.05), the effect being apparent from the first evaluation at 15 minutes (P<.05). The STPIS reduction in favour of ibuprofen 25 mg was not significant vs placebo. Mean STRS scores and patient's global efficacy assessment both reflected a higher efficacy of ibuprofen 25 mg over the 4-day treatment period with tests of statistical significance up to day 1 evening (P<.05), and, in patients with still clinically significant pain (n=128), after an average 4 days (P<.01). Ibuprofen 25 mg lozenge was well tolerated with a safety profile similar to placebo., Conclusion: Low-dose ibuprofen 25 mg lozenge in repeat dosing provides in adults more efficacious and rapid relief of sore throat pain and is as well tolerated as placebo., Clinical Trial Registration: ClinicalTrials.gov, NCT01785862., (© 2017 John Wiley & Sons Ltd.)

Introduction: Intrathecal (IT) drug infusion is an appropriate and necessary tool in the algorithm to treat refractory cancer and noncancer pain. The decision-making steps/methodology for selecting appropriate patients for implanted targeted drug delivery systems is controversial and complicated. Therefore, a consensus on best practices for determining appropriate use of IT drug infusion may involve testing/trialing this therapy before implantation., Methods: This current Polyanalgesic Consensus Conference (PACC) update was designed to address the deficiencies and emerging innovations since the previous PACC convened in 2012. A literature search identified publications available since the previous PACC publications in 2014, and relevant sources were contributed by the PACC members. After reviewing the literature, the panel determined the evidence levels and degrees of recommendations. The developed consensus was ranked as strong (>80%), moderate (50-79%), or weak (<49%)., Results: The trialing for IT drug delivery systems (IDDS) remains an area of continued controversy. The PACC recommendations for trialing are presented in 34 consensus points and cover trialing for morphine, ziconotide, and medication admixtures; starting doses and titration practices; measurements of success; trial settings and monitoring; management of systemic opioids during trialing; and the role of psychological evaluation. Finally, the PACC describes clinical scenarios in which IT trialing is required or not required., Conclusion: The PACC provides consensus guidance on best practices of trialing for IDDS implants. In addition, the PACC recommends that no trial may be required in certain patient populations., (© 2017 International Neuromodulation Society.)

Introduction: The use of neurostimulation for pain has been an established therapy for many decades and is a major tool in the arsenal to treat neuropathic pain syndromes. Level I evidence has recently been presented to substantiate the therapy, but this is balanced against the risk of complications of an interventional technique., Methods: The Neurostimulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society convened an international panel of well published and diverse physicians to examine the best practices for infection mitigation and management in patients undergoing neurostimulation. The NACC recommendations are based on evidence scoring and peer-reviewed literature. Where evidence is lacking the panel added expert opinion to establish recommendations., Results: The NACC has made recommendations to improve care by reducing infection and managing this complication when it occurs. These evidence-based recommendations should be considered best practices in the clinical implantation of neurostimulation devices., Conclusion: Adhering to established standards can improve patient care and reduce the morbidity and mortality of infectious complications in patients receiving neurostimulation., (© 2017 International Neuromodulation Society.)

Introduction: The Neurostimulation Appropriateness Consensus Committee (NACC) was formed by the International Neuromodulation Society (INS) in 2012 to evaluate the evidence to reduce the risk of complications and improve the efficacy of neurostimulation. The first series of papers, published in 2014, focused on the general principles of appropriate practice in the surgical implantation of neurostimulation devices. The NACC was reconvened in 2014 to address specific patient care issues, including bleeding and coagulation., Methods: The INS strives to improve patient care in an evidence-based fashion. The NACC members were appointed or recruited by the INS leadership for diverse expertise, including international clinical expertise in many areas of neurostimulation, evidence evaluation, and publication. The group developed best practices based on peer-reviewed evidence and, in the absence of specific evidence, on expert opinion. Recommendations were based on international evidence in accordance with guideline creation., Conclusions: The NACC has recommended specific measures to reduce the risk of bleeding and neurological injury secondary to impairment of coagulation in the setting of implantable neurostimulation devices in the spine, brain, and periphery., (© 2017 International Neuromodulation Society.)

Objective: To assess the effectiveness and tolerability of tapentadol sustained release (SR) following its introduction to the Australian private market., Design: A retrospective audit of routine clinical practice with data collection beginning 2 months after the first tapentadol SR prescription., Setting: A multidisciplinary Australian pain clinic., Patients: Fifty patients who were prescribed tapentadol SR as part of routine clinical management at the pain clinic., Interventions: Trial of tapentadol SR with subsequent dose titration if the patient was satisfied with or tolerant of the medication., Main Outcome Measures: Patient-reported pain outcome, side effects, medication adherence, and concomitant analgesic medications., Results: Sixty-eight percent of patients reported major reductions in pain. Seventy-two percent of patients tolerated and adhered to treatment and 76 percent reported no side effects. Pain outcome was independent of pain type and prior opioid exposure; however, patients taking tapentadol in combination were more likely to report a positive outcome (Pearson χ(2) = 9.867, n = 46, p = 0.0072)., Conclusions: Tapentadol was effective and generally well tolerated in the majority of patients for neuropathic, nociceptive and mixed pain types and this was regardless of prior opioid use.

Background: Evidence suggests that complex regional pain syndrome (CRPS) is a manifestation of microvascular dysfunction. Topical combinations of α2-adrenergic receptor agonists or nitric oxide donors with phosphodiesterase or phosphatidic acid inhibitors formulated to treat microvascular dysfunction have been shown to reduce allodynia in a rat model of CRPS-I. Driven by these findings, we assessed the outcomes of CRPS patients treated with a compound analgesic cream (CAC) consisting of ketamine 10%, pentoxifylline 6%, clonidine 0.2%, and dimethyl sulfoxide 6% to 10%., Methods: An audit was conducted on 13 CRPS patients who trialed the CAC. A detailed report was compiled for each patient which comprised baseline characteristics, including CRPS description, previous treatments, and pain scores (numerical pain rating scale; 0 to 10). Recorded outcomes consisted of pain scores, descriptive outcomes, and concurrent medications/treatments, for which basic analysis was performed to determine the effectiveness of the CAC. Case reports are presented for 3 patients with varying outcomes., Results: Nine patients (69%) reported pain/symptom reduction (4.4 ± 2.1 vs. 6.3 ± 1.9) with use of the CAC. Six patients reported sustained benefits after 2 months of CAC use, and 2 patients reported complete resolution of pain/symptoms: one had early CRPS-I and the other received a partial CRPS diagnosis. An otherwise medication refractory and intolerant patient found partial benefit with the CAC., Conclusions: These results demonstrate promise for this topical combination as a useful treatment in multimodal therapy for patients with CRPS, with the potential to resolve pain/symptoms in early CRPS patients., (© 2015 World Institute of Pain.)

Peripheral nerve stimulation (PNS) generally refers to stimulation of a named nerve via direct placement of a lead next to the nerve either via a percutaneous or open approach; in peripheral nerve field stimulation (PNFS), leads are subcutaneously placed to stimulate the region of affected nerves, cutaneous afferents, or the dermatomal distribution of the nerves which converge back to the spinal cord. Recently, there has been a renewed interest in using the PNS approach for many otherwise refractory pain conditions; however, PNFS appears to be more effective for the management of low back pain and therefore more attractive. Here we discuss procedural details of PNFS trial and implant, and provide scientific and clinical rationale for placing PNFS electrodes at a certain depth under the skin. We also summarize results of published studies on use of PNFS in the management of low back pain and list the criteria that are used for proper patient selection. Our experience and the published studies provide evidence that PNFS is a safe and well-tolerated pain control option for intractable pain conditions, including chronic low back pain. Notably, achieving efficacious pain relief relies on correct patient selection and the optimal placement of the leads, ensuring, in particular, a lead depth of 10-12 mm from the surface to maximize the target sensation (mediated by fast-adapting Aβ fibers) of PNFS, which is believed to be most effective for the pain relief., (© 2016 S. Karger AG, Basel.)