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Nagy A Mekhail,1 Shrif J Costandi,1 Sherif Armanyous,1 Ricardo Vallejo,2 Lawrence R Poree,3 Lora L Brown,4 Stanley Golovac,5 Timothy R Deer6 1Evidence-Based Pain Management Research, Cleveland Clinic, Cleveland, OH, USA; 2Millennium Pain Center, Bloomington, IL, USA; 3Pain Management Center, UCSF Health, San Francisco, CA, USA; 4TruWell Health, St. Petersburg, FL, USA; 5Florida Pain Institute, Merritt Island, FL, USA; 6Center for Pain Relief, Charleston, WV, USACorrespondence: Nagy A Mekhail Email mekhain@ccf.orgBackground and Purpose: Minimally invasive lumbar decompression (mild®) is an effective long-term therapy for patients with symptomatic lumbar spinal stenosis (LSS) resulting primarily from hypertrophic ligamentum flavum (HLF). Most subjects in clinical studies of the mild procedure have been older adults (age≥ 65). While the incidence of LSS increases with age, a substantial number of adults (age< 65) also suffer from neurogenic claudication secondary to HLF. In this report, outcomes of mild were compared between adults and older adults.Patients and Methods: All prospective studies of the mild procedure with a 1-year follow-up completed since the beginning of 2012 that allowed the inclusion of adult patients of all ages were reviewed. Outcomes of visual analog scale (VAS), Oswestry Disability Index (ODI), Pain Disability Index (PDI), Roland Morris Low Back Pain and Disability Questionnaire (RMQ), standing time and walking distance were compared for adults and older adults.Results: Four studies met the inclusion criteria, resulting in an analysis of 49 adults and 160 older adults. Patients in both age groups experienced significant mean improvements in all but one outcome measure at 6- and 12-month follow-up. Differences between the two age groups in all scores at 6 and 12 months were not statistically significant.Conclusion: Analysis of the four studies indicated that symptom improvements for adults and older adults were significant from baseline, and no statistically significant difference was observed between the two age groups. These results illustrate that mild can be an effective treatment for LSS due primarily to HLF, regardless of the adult patient age.Keywords: mild, neurogenic claudication, ligamentum flavum, LSS

Objectives: Spinal cord stimulation (SCS) has been challenged by the lack of neurophysiologic data to guide therapy optimization. Current SCS programming by trial-and-error results in suboptimal and variable therapeutic effects. A novel system with a physiologic closed-loop feedback mechanism using evoked-compound action potentials enables the optimization of physiologic neural dose by consistently and accurately activating spinal cord fibers. We aimed to identify neurophysiologic dose metrics and their ranges that resulted in clinically meaningful treatment responses., Materials and Methods: Subjects from 3 clinical studies (n = 180) with baseline back and leg pain ≥60 mm visual analog scale and physical function in the severe to crippled category were included. Maximal analgesic effect (MAE) was operationally defined as the greatest percent reduction in pain intensity or as the greatest cumulative responder score (minimal clinically important differences [MCIDs]) obtained within the first 3 months of SCS implant. The physiologic metrics that produced the MAE were analyzed., Results: We showed that a neural dose regimen with a high neural dose accuracy of 2.8μV and dose ratio of 1.4 resulted in a profound clinical benefit to chronic pain patients (MAE of 79 ± 1% for pain reduction and 12.5 ± 0.4 MCIDs). No differences were observed for MAE or neurophysiological dose metrics between the trial phase and post-implant MAE visit., Conclusion: For the first time, an evidence-based neural dose regimen is available for a neurostimulation intervention as a starting point to enable optimization of clinical benefit, monitoring of adherence, and management of the therapy., Competing Interests: Conflict of Interest Robert M. Levy is an uncompensated consultant for Biotronik, Abbott, Nalu, Saluda, and Mainstay Medical and has stock options from Nalu and Saluda Medical. Nagy A. Mekhail reports receiving grants from Neuros, Mesoblast, and Vivex Biologics, as well as consulting as a medical monitor for Saluda Medical, Nevro, Vivex Biologics, Mainstay, Presidio Medical, and Vertos outside the submitted work. Leonardo Kapural reports receiving grants from Nevro, Neuros, Avanos, Medtronic, Neuralace, and Xalud Therapeutics and financial support from Nevro, Avanos, and Saluda Medical outside the submitted work. Christopher A. Gilmore reports personal fees and other assistance from SPR, and personal fees from Nevro, Nalu, Biotronik, Boston Scientific, and Saluda Medical outside the submitted work. Erika A. Petersen has received research support from Mainstay, Medtronic, Neuros Medical, Nevro Corp, ReNeuron, SPR, and Saluda Medical outside the submitted work, as well as personal fees from Abbott Neuromodulation, Biotronik, Medtronic Neuromodulation, Nalu, Neuros Medical, Nevro, Presidio Medical, Saluda Medical, and Vertos outside the submitted work. She holds stock options from SynerFuse and neuro42. Jonathan H. Goree is a consultant for Saluda Medical, Abbott, and Stratus Medical outside the submitted work. He has received research support paid to the institution by SPR Therapeutics and Mainstay Medical. Jason E. Pope reports research and consulting fees from Saluda Medical during the conduct of the study; stock options from Saluda Medical; consultancy for Abbott, Medtronic, Saluda Medical, Flowonix, SpineThera, Vertos, Vertiflex, SPR Therapeutics, Tersera, Aurora, Spark, Ethos, Biotronik, Mainstay, WISE, Boston Scientific, and Thermaquil outside the submitted work; has received grant and research support from Abbott, Flowonix, Aurora, Painteq, Ethos, Muse, Boston Scientific, SPR Therapeutics, Mainstay, Vertos, AIS, and Thermaquil outside the submitted work; and is a minority shareholder of Vertos, Stimgenics, SPR Therapeutics, Painteq, Aurora, Spark, Celeri Health, Neural Integrative Solutions, Pacific Research Institute, Thermaquil, Abbott and Anesthetic Gas Reclamation. Shrif J. Costandi reports receiving grants from Saluda Medical, Vertos, Mainstay, and Vivex outside the submitted work. Jan Willem Kallewaard is an advisory board member for Boston Scientific, Medtronic, Abbott, and Saluda Medical. Simon Thomson has received consultancy fees from Boston Scientific, Mainstay Medical, and Saluda Medica outside the submitted work. He has received department research funding from the National Institute for Health Research, Boston Scientific, Saluda Medical, and Mainstay Medical. Christopher Gilligan reports consulting fees and stock options received from Mainstay, personal fees from Mainstay, Saluda Medical, Persica, and Iliad outside the submitted work, research funded by Sollis, expert witness testimony fees, and serves as Editor-in-Chief of Pain Practice. Corey W. Hunter has received consultancy fees from Saluda Medical and Genecentrix outside the submitted work. Kasra Amirdelfan reports consultancy for Medtronic, Nevro, Boston Scientific, Nalu, Presidio, Biotronik, Mesoblast, and Vivex Laboratories outside the submitted work. Steven M. Falowski reports consulting fees from Abbott, Medtronic, Saluda, VertiFlex, Vertos, Surgentec, CornerLoc, Mainstay, and Relievant outside the submitted work, has received a grant for research funding from Mainstay, Relievant, Medtronic, Abbott, VertiFlex, Saluda, Nalu, CornerLoc, Aurora, Biotronik, and Stimgenics outside the submitted work, and has an equity position in SynerFuse, Aurora Spine, Thermaquil. SPR Therapeutics, Saluda, CornerLoc, PainTEQ, Stimgenics, Anesthetic Gas Reclamation, Neural Integrative Solutions, SpineThera, and Celeri Health. Sean Li reports receiving grants and personal fees from Saluda Medical during the conduct of the study; he reports grants from Avanos, Nalu Medical, SPR Therapeutics, Averitas Pharma, Biotronik, Neuralace, Presidio, SGX Therapeutics, and PainTeq, as well as consultancy for Abbott, Avanos, Presidio, SPR Therapeutics, Averitas Pharma, Biotronik, Nalu Medical, PainTeq, and Vertos Medical outside the submitted work, as well as holding stock options for Nalu Medical and NeuroOne. Shivanand P. Lad reports personal fees from Mainstay Medical and Nevro outside the submitted work; he is a consultant for Abbott Laboratories, Boston Scientific, Higgs Boson Health, Medtronic, Minnetronix, Nevro, and Presidio Medical. Dawood Sayed reports personal fees from Abbott, Boston Scientific, Flowonix, Medtronic, Nevro, Saluda, and Vertiflex outside the submitted work, personal fees and stock options from Mainstay, SPR Therapeutics, PainTEQ, and Vertos, and stock options from Neuralace and Surgentec. Ajay Antony reports consultancy fees from Boston Scientific outside the submitted work. Timothy R. Deer reports consultancy for Axonics, Abbott, Nalu, Vertos, SpineThera, Mainstay, Cornerloc, Ethos, SPR Therapeutics, Medtronic, Boston Scientific, PainTeq, Saluda Medical, Tissue Tech, Spinal Simplicity, and Avanos outside the submitted work. Maged N. Guirguis has received consulting fees from Avanos Medical, Avertis Pharmacy, Boston Scientific, and Saluda Medical outside the submitted work, as well as research support from Boston Scientific, Neuros Medical, Nevro Corp, and Saluda Medical outside the submitted work. Aaron K. Calodney reports personal fees from Medtronic, Nevro, Stryker, PainTeq, Saluda Medical, and Boston Scientific outside the submitted work. Brian Bruel reports consultancy for Saluda Medical, Boston Scientific, Spinal Simplicity, Biotronik, TerSera, Stratus, and Neurovasis outside the submitted work. Patrick Buchanan reports consulting fees from Saluda Medical, Abbott, and PainTEQ outside the submitted work. Nicole Soliday, Rui V. Duarte, and Angela Leitner report being employees of Saluda Medical. Peter S. Staats has received consultancy fees from Medtronic, Saluda Medical, Nalu, and Biotronic outside the submitted work, and has stock options from Saluda Medical and Nalu. The remaining authors report no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Chronic pain is a personal experience influenced by multiple biopsychosocial factors. Using a pain intensity measure alone to assess the effectiveness of a chronic pain intervention fails to fully evaluate its impact on the multifaceted chronic pain experience. The holistic minimal clinically important difference (MCID) is a composite outcome developed to provide a comprehensive assessment of chronic pain in response to intervention, across 5 outcome domains: pain intensity, health-related quality of life, sleep quality, physical, and emotional function. To focus on domains where the individual need is greatest, the holistic MCID reflects the cumulative MCID averaged over only the domains where subjects were impaired preintervention., Objectives: To assess the internal and construct validity of the Holistic MCID score to inform its future use as an evidence-based tool., Methods: This validation study was undertaken using data from the EVOKE trial with 111 patients up to 24-month follow-up. Internal consistency of the holistic MCID was assessed using Cronbach alpha statistic and dimensional exploration using principal component analysis., Results: The holistic MCID measure demonstrated strong internal consistency with Cronbach alpha >0.7 at all follow-ups. Principal component analysis showed one overarching holistic dimension to be present in the composite. Construct validity was demonstrated by an increase in the holistic MCID score being associated with both increased Patients' Global Impression of Change, EuroQol visual analogue scale score, and each of the outcome domains in a "leave-one-out" analysis (all P < 0.001)., Conclusion: The holistic MCID provides a valid measure for the comprehensive, personalized assessment of response after a chronic pain intervention. The validity of the holistic MCID requires further confirmation in other chronic pain populations and with different interventions., Competing Interests: R.S.T. reports consultancy fees from Medtronic, Nevro and Saluda Medical outside the submitted work. C.M.M. is employed by NAMSA, a company that provides consulting and testing services to medical device manufacturers. N.A.M. reports receiving grants from Neuros, Mesoblast, and Vivex Biologics, as well as consulting as a medical monitor for Saluda Medical, Nevro, Vivex Biologics, Mainstay, Sollis Therapeutics, and Vertos outside the submitted work. J.W.K. is an advisory board member for Boston Scientific, Medtronic, Abbott, and Saluda Medical. J.E.P. reports research and consulting fees from Saluda Medical during the conduct of the study; consultancy for Abbott, Medtronic, Saluda Medical, Flowonix, SpineThera, Vertos, Vertiflex, SPR Therapeutics, Tersera, Aurora, Spark, Ethos, Biotronik, Mainstay, WISE, Boston Scientific, and Thermaquil outside the submitted work; has received grant and research support from: Abbott, Flowonix, Aurora, Painteq, Ethos, Muse, Boston Scientific, SPR Therapeutics, Mainstay, Vertos, AIS, and Thermaquil outside the submitted work; and is a shareholder of Vertos, SPR Therapeutics, Painteq, Aurora, Spark, Celeri Health, Neural Integrative Solutions, Pacific Research Institute, Thermaquil, and Anesthetic Gas Reclamation. C.W.H. has received consultancy fees from Saluda Medical and Genecentrix outside the submitted work. S.J.C. reports receiving grants from Saluda Medical, Vertos, Mainstay, and Vivex outside the submitted work. L.K. reports receiving grants from Nevro, Neuros, Avanos, Medtronic, Neuralace, and Xalud Therapeutics and financial support from Nevro, Avanos, and Saluda Medical outside the submitted work. C.A.G. reports personal fees and other from SPR, and personal fees from Nevro, Nalu, Biotronik, Boston Scientific and Saluda Medical outside the submitted work. E.A.P. has received research support from Mainstay, Medtronic, Neuros Medical, Nevro Corp, ReNeuron, SPR, and Saluda Medical outside the submitted work, as well as personal fees from Abbott Neuromodulation, Biotronik, Medtronic Neuromodulation, Nalu, Neuros Medical, Nevro, Presidio Medical, Saluda Medical, and Vertos outside the submitted work. She holds stock options from SynerFuse and neuro42. K.V.P. is a consultant and speaker for Abbott. S.E. reports consultancy fees from Medtronic, and Mainstay Medical outside the submitted work. He has received department research funding from the National Institute of Health Research, Saluda Medical and Medtronic. R.M.L. is an uncompensated consultant for Biotronik, Abbott, Nalu, Saluda Medical, and Mainstay Medical and has stock options from Nalu and Saluda Medical. C.G. reports payment to his institution (for part of his salary) and stock options received from Mainstay, personal fees from Mainstay, Saluda Medical, Persica, and Iliad outside the submitted work, research funded by Sollis, expert witness testimony fees, and serves as Editor-in-Chief of Pain Practice. S.D. has received consulting payments from Averitas Pharma and Biotronik outside the submitted work. A.A. reports consultancy for Medtronic, Avanos, and StimWave outside the submitted work. P.B. reports consulting fees from Abbott and PainTEQ outside the submitted work. E.H., A.L., N.S. and R.V.D. are employees of Saluda Medical. R.V.D. has previously received consultancy fees from Mainstay Medical, Medtronic, and Saluda Medical. D.J.C. has consulted for AbbVie, Heron Therapeutics, Aptinyx, Neumentum, Regeneron Pharmaceuticals, Swing Therapeutics, Virios Therapeutics, Allergan Sales, Eli Lilly and Company, H. Lundback A/S, Pfizer, Samumed, Tonix Pharmaceuticals. T.J.N. has received consultancy fees from Saluda Medical outside the submitted work. The remaining authors declare no conflict of interest.Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.)

Background: The SENZA-PDN study evaluated high-frequency 10-kHz spinal cord stimulation (SCS) for the treatment of painful diabetic neuropathy (PDN). Over 24 months, 10-kHz SCS provided sustained pain relief and improved health-related quality of life. This report presents additional outcomes from the SENZA-PDN study, focusing on diabetes-related pain and quality of life outcomes., Methods: The SENZA-PDN study randomized 216 participants with refractory PDN to receive either conventional medical management (CMM) or 10-kHz SCS plus CMM (10-kHz SCS + CMM), allowing crossover after six months if pain relief was insufficient. Postimplantation assessments at 24 months were completed by 142 participants with a permanent 10-kHz SCS implant, comprising 84 initial and 58 crossover recipients. Measures included the Brief Pain Inventory for Diabetic Peripheral Neuropathy (BPI-DPN), Diabetes-Related Quality of Life (DQOL), Global Assessment of Functioning (GAF), and treatment satisfaction., Results: Over 24 months, 10-kHz SCS treatment significantly reduced pain severity by 66.9% ( P < .001; BPI-DPN) and pain interference with mood and daily activities by 65.8% ( P < .001; BPI-DPN). Significant improvements were also observed in overall DQOL score ( P < .001) and GAF score ( P < .001), and 91.5% of participants reported satisfaction with treatment., Conclusions: High-frequency 10-kHz SCS significantly decreased pain severity and provided additional clinically meaningful improvements in DQOL and overall functioning for patients with PDN. The robust and sustained benefits over 24 months, coupled with high participant satisfaction, highlight that 10-kHz SCS is an efficacious and comprehensive therapy for patients with PDN., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: EAP has received consulting fees from Abbott Laboratories, Biotronik, Boston Scientific, Medtronic Neuromodulation, Nalu Medical, Neuros Medical, Nevro Corp, Presidio Medical, Saluda, and Vertos Medical; research support from Mainstay, Medtronic Neuromodulation, Nalu Medical, Neuros Medical, Nevro Corp, ReNeuron, Saluda, and SPR; and stock options from neuro42 and SynerFuse. TGS has received research support from Nevro Corp. JAS has received research support from Boston Scientific, Nevro Corp, Saluda Medical, and Vertiflex. MJJ is an employee of Nevro Corp. DRE received a fee from Nevro Corp for the preparation of this manuscript in her capacity as an independent medical writer. JLW has received consulting fees from California Institute for Biomedical Research and Eli Lilly and research support from Nevro Corp. SMS has received research support from Nevro Corp. KA has received consulting fees from Biotronik, Medtronic, Nalu Medical, Nevro Corp, and Saluda Medical, as well as research support from Biotronik, IPM Medical Group, Nevro Corp, Saluda Medical, SPR Therapeutics, and Vivex Biologics. MNG has received consulting fees from Abbott Laboratories, Avanos Medical, Avertis Pharmacy, Boston Scientific, Nevro Corp, and Saluda Medical, as well as research support from Abbott Laboratories, Avanos Medical, Boston Scientific, Nalu Medical, Neuros Medical, Nevro Corp, and Saluda Medical. JX has received research support from the Cleveland Clinic Velosano Program, the National Institutes of Health, the Steve and Melody Golding Foundation, and Nevro Corp. CY has received research support from Nevro Corp. AN has received consulting fees from Aurora Spine, Flowonix, and Nevro Corp, as well as research support from Nevro Corp. DGP has received consulting fees from Abbott Laboratories, AIS Healthcare, Allergan, Amgen, Aurora Spine, CornerLoc, Flowonix, Lundbeck, Pajunk Medical, Saluda Medical, Spark Biomedical, and Vertos Medical; research support from Abbott Laboratories, Aurora Spine, Flowonix, Nevro Corp, and Saluda Medical; speakers’ bureau or honoraria from Abbott Laboratories, Allergan, Amgen, CornerLoc, Lundbeck, Saluda Medical, and Vertos Medical; and stock options from CornerLoc. MJC has received research support from Nevro Corp. VG has received research support from Biotronik, Medtronic, Nevro Corp, PainTEQ, SPR Therapeutics, and St. Jude. RHB has received research support from Nevro Corp. NDM has received consulting fees from Averitas, Nevro Corp, and Salix Pharmaceuticals, as well as research support from Boston Scientific and Nevro Corp. DS has received consulting fees from Abbott Laboratories, Boston Scientific, Flowonix, Medtronic, Nevro Corp, Vertiflex, and Vertos Medical, as well as research support from Abbott Laboratories, Biotronik, Nevro Corp, Vertiflex, and Vertos Medical. SPL has received consulting fees from Nevro Corp and research support from Nevro Corp. DJD has received research support from Nevro Corp, as well as funding for serving as principal investigator of a study supported by SPR Therapeutics paid to his institution. KAS has received research support from Nevro Corp. JHG has received consulting fees from Abbott Laboratories, Saluda Medical, and Stratus Medical. PWW has received research support from Nevro Corp. CEA has received consulting fees from AbbVie, Amgen, Biohaven, Clexio Biosciences, Collegium, Eli Lilly, Elsevier, Flowonix, Gene Pharma, Lundbeck, Nevro Corp, Novartis, Pfizer, SK Life Science, Teva Pharmaceutical, and Vertex, as well as research support from AbbVie, Allergan, Amgen, Daiichi Sankyo, Eli Lilly, Novartis, Teva Pharmaceutical, and Vertex Pharmaceuticals. CEN has received consulting fees from Exelixis, Neurogastrx, and Nevro Corp, as well as research support from Nevro Corp. RST has received consulting fees from Nevro Corp, Medtronic, and Saluda Medical. DLC is an employee of Nevro Corp. NAM has received consulting fees from Nevro Corp, Relievant Medsystems, Saluda Medical, Sollis Therapeutics, and Vertos Medical, as well as research support from Avanos Medical, Mesoblast, Neuros Medical, and Nevro Corp.

Objectives: Different types of spinal cord stimulation (SCS) have been evaluated for the management of chronic nonsurgical refractory back pain (NSRBP). A direct comparison between the different types of SCS or between closed-loop SCS with conventional medical management (CMM) for patients with NSRBP has not been previously conducted, and therefore, their relative effectiveness and cost-effectiveness remain unknown. The aim of this study was to perform a systematic review, network meta-analysis (NMA) and economic evaluation of closed-loop SCS compared with fixed-output SCS and CMM for patients with NSRBP., Methods: Databases were searched to September 8, 2023. Randomized controlled trials of SCS for NSRBP were included. The results of the studies were combined using fixed-effect NMA models. A cost-utility analysis was performed from the perspective of the UK National Health Service with results reported as incremental cost per quality-adjusted life-year (QALY)., Results: Closed-loop SCS resulted in statistically and clinically significant reductions in pain intensity (mean difference [MD] 32.72 [95% CrI 15.69-49.78]) and improvements in secondary outcomes (Oswestry Disability Index [ODI] and health-related quality of life [HRQoL]) compared with fixed-output SCS at 6-month follow-up. Compared with CMM, both closed-loop and fixed-output SCS resulted in statistically and clinically significant reductions in pain intensity (closed-loop SCS vs. CMM MD 101.58 [95% CrI 83.73-119.48]; fixed-output SCS versus CMM MD 68.86 [95% CrI 63.43-74.31]) and improvements in secondary outcomes (ODI and HRQoL). Cost-utility analysis showed that closed-loop SCS dominates fixed-output SCS and CMM, and fixed-output SCS also dominates CMM., Discussion: Current evidence showed that closed-loop and fixed-output SCS provide more benefits and cost-savings compared with CMM for patients with NSRBP., Competing Interests: This work was supported by Saluda Medical. S.E. reports consultancy fees from Medtronic, and Mainstay Medical outside the submitted work. He has received department research funding from the National Institute of Health Research, Saluda Medical and Medtronic. S.N. reports consultancy fees from Saluda Medical. A.B. MTech Access was commissioned by Saluda Medical to participate in this project. N.A.M. reports receiving grants from Neuros, Mesoblast, and Vivex Biologics, as well as consulting as a medical monitor for Saluda Medical, Nevro, Vivex Biologics, Mainstay, Sollis Therapeutics, and Vertos outside the submitted work. C.G. reports consulting fees and stock options received from Mainstay, personal fees from Mainstay, Saluda Medical, Persica, and Iliad outside the submitted work, research funded by Sollis, expert witness testimony fees, and serves as Editor-in-Chief of Pain Practice. B.B. reports an educational grant from Saluda Medical and consultancy fees from Salvia Bioelectronics, Medtronic and Abbott outside the submitted work. P.S.S. has received consultancy fees from Medtronic, Saluda Medical, Nalu, and Biotronic outside the submitted work, and has stock options from Saluda Medical and Nalu. M.M. reports no conflicts of interest. N.S., A.L., and R.V.D. are employees of Saluda Medical. R.V.D. has previously received consultancy fees from Mainstay Medical, Medtronic, and Saluda Medical outside the submitted work., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Introduction: The evidence for spinal cord stimulation (SCS) has been criticized for the absence of blinded, parallel randomized controlled trials (RCTs) and limited evaluations of the long-term effects of SCS in RCTs. The aim of this study was to determine whether evoked compound action potential (ECAP)-controlled, closed-loop SCS (CL-SCS) is associated with better outcomes when compared with fixed-output, open-loop SCS (OL-SCS) 36 months following implant., Methods: The EVOKE study was a multicenter, participant-blinded, investigator-blinded, and outcome assessor-blinded, randomized, controlled, parallel-arm clinical trial that compared ECAP-controlled CL-SCS with fixed-output OL-SCS. Participants with chronic, intractable back and leg pain refractory to conservative therapy were enrolled between January 2017 and February 2018, with follow-up through 36 months. The primary outcome was a reduction of at least 50% in overall back and leg pain. Holistic treatment response, a composite outcome including pain intensity, physical and emotional functioning, sleep, and health-related quality of life, and objective neural activation was also assessed., Results: At 36 months, more CL-SCS than OL-SCS participants reported ≥50% reduction (CL-SCS=77.6%, OL-SCS=49.3%; difference: 28.4%, 95% CI 12.8% to 43.9%, p<0.001) and ≥80% reduction (CL-SCS=49.3%, OL-SCS=31.3%; difference: 17.9, 95% CI 1.6% to 34.2%, p=0.032) in overall back and leg pain intensity. Clinically meaningful improvements from baseline were observed at 36 months in both CL-SCS and OL-SCS groups in all other patient-reported outcomes with greater levels of improvement with CL-SCS. A greater proportion of patients with CL-SCS were holistic treatment responders at 36-month follow-up (44.8% vs 28.4%), with a greater cumulative responder score for CL-SCS patients. Greater neural activation and accuracy were observed with CL-SCS. There were no differences between CL-SCS and OL-SCS groups in adverse events. No explants due to loss of efficacy were observed in the CL-SCS group., Conclusion: This long-term evaluation with objective measurement of SCS therapy demonstrated that ECAP-controlled CL-SCS resulted in sustained, durable pain relief and superior holistic treatment response through 36 months. Greater neural activation and increased accuracy of therapy delivery were observed with ECAP-controlled CL-SCS than OL-SCS., Trial Registration Number: NCT02924129., Competing Interests: Competing interests: NM reports personal fees from Saluda Medical for acting as independent medical monitor for the EVOKE study during the conduct of the study; he reports receiving grants from Neuros and Mesoblast, as well as consulting as a medical monitor for Nevro, Vivex, Mainstay, and Vertos outside the submitted work. RL is an uncompensated consultant for Nalu, Saluda Medical, and Mainstay Medical and has stock options from Nalu and Saluda Medical obtained before 2019, not exercisable through the duration of his term as International Neuromodulation Society President and editor-in-chief of the journal Neuromodulation: Technology at the Neural Interface. TD reports personal fees from Saluda Medical during the conduct of the study; consultancy for Axonics, Abbott, Nalu, Vertos, SpineThera, Mainstay, Cornerloc, Ethos, SPR Therapeutics, Medtronic, Boston Scientific, PainTeq, Tissue Tech, Spinal Simplicity, and Avanos outside the submitted work. He is a minor equity holder for Saluda Medical, Nalu, SpineThera, Stimgenics, Vertiflex, Vertos, and Bioness and an advisory board member for Abbott, Vertos, Nalu, SPR Therapeutics, and Tissue Tech. LK reports receiving grants from Nevro, Neuros, Avanos, Medtronic, Neuralace, and Xalud Therapeutics and financial support from Nevro, Avanos, and Saluda Medical outside the submitted work. SL reports receiving grants and personal fees from Saluda Medical during the conduct of the study; he reports grants from Avanos, Boston Scientific, Nalu Medical, SPR Therapeutics, Averitas Pharma, Biotronik, SGX Therapeutics, and PainTeq, as well as consultancy for Abbott, Avanos, Boston Scientific, Nevro, SPR Therapeutics, Averitas Pharma, Biotronik, Nalu Medical, and PainTeq, outside the submitted work, as well as holding stock options for Nalu Medical. KA reports consultancy for Medtronic, Nevro, Boston Scientific, Nalu, Presidio, Biotronik, Mesoblast, Vivex Laboratories outside the submitted work. JP reports research and consulting fees from Saluda Medical during the conduct of the study; consultancy for Abbott, Medtronic, Saluda Medical, Flowonix, SpineThera, Vertos, Vertiflex, SPR Therapeutics, Tersera, Aurora, Spark, Ethos, Biotronik, Mainstay, WISE, Boston Scientific, and Thermaquil outside the submitted work; has received grant and research support from: Abbott, Flowonix, Aurora, Painteq, Ethos, Muse, Boston Scientific, SPR Therapeutics, Mainstay, Vertos, AIS, and Thermaquil outside the submitted work; and is a shareholder of Vertos, SPR Therapeutics, Painteq, Aurora, Spark, Celeri Health, Neural Integrative Solutions, Pacific Research Institute, Thermaquil, and Anesthetic Gas Reclamation. CH reports grants from Saluda Medical during the conduct of the study; consultancy fees from Genecentrix outside the submitted work. SC reports grants from Cleveland Clinic during the conduct of the study; and grants from Vertos, Mainstay, and Vivex outside the submitted work. SMF reports consulting fees from Abbott, Medtronic, Saluda, VertiFlex, Vertos, Surgentec, CornerLoc, Mainstay and Relievant outside the submitted work, has received grant for research funding from Mainstay, Relievant, Medtronic, Abbott, VertiFlex, Saluda, Nalu, CornerLoc, Aurora, Biotronik, and Stimgenics outside the submitted work, and has an equity position in SynerFuse, Aurora Spine, Thermaquil. SPR Therapeutics, Saluda, CornerLoc, PainTEQ, Stimgenics, Anesthetic Gas Reclamation, Neural Integrative Solutions, SpineThera, and Celeri Health. CG reports clinical trial funding from Saluda Medical during the conduct of the study; reports personal fees and other from SPR, and personal fees from Nevro, Nalu, Biotronik, and Boston Scientific outside the submitted work. PSS has received consultancy fees from Medtronic, Saluda Medical, Nalu, and Biotronic outside the submitted work, and has stock options from Saluda Medical and Nalu. JS reports personal fees from Nevro during the conduct of the study and personal fees from Saluda Medical and Boston Scientific outside the submitted work. TM reports research fees from Saluda Medical during the conduct of the study and personal fees from Nevro outside the submitted work. JC reports personal fees from Saluda Medical during the conduct of the study; personal fees from Abbott, Boston Scientific, Nevro, Medtronic, Mainstay, SPR Therapeutics, CornerLoc, PillNurse, Biotronik, and Vivex outside the submitted work; and stock from Mainstay, CornerLoc, and PillNurse. EP has received research support from Mainstay, Medtronic, Neuros Medical, Nevro Corp, ReNeuron, SPR, and Saluda Medical outside the submitted work, as well as personal fees from Abbott Neuromodulation, Biotronik, Medtronic Neuromodulation, Nalu, Neuros Medical, Nevro, Presidio Medical, Saluda Medical, and Vertos outside the submitted work. She holds stock options from SynerFuse and neuro42. JMH reports consulting fees from Abbott, Boston Scientific, Nevro, and Saluda Medical outside the submitted work. RR reports grants from SPR, Nalu and Nevro outside the submitted work,l fees from Presidio, and grants and personal fees from Boston Scientific and Saluda Medical outside the submitted work. JWK is an advisory board member for Boston Scientific, Medtronic, Abbott, and Saluda Medical. GB reports consulting fees from Medtronic, Boston Scientific, and Saluda Medical outside the submitted work, and has a consulting agreement and is on the advisory board for Nevro Corp, Nalu Medical Inc, Abbott, and Boston Scientific. RST reports consulting fees from Medtronic, Nevro and Saluda Medical outside the submitted work. LP reports personal fees from Saluda Medical; is a member of the data monitoring board of Saluda Medical during the conduct of the study; and reports personal consulting fees from Medtronic and Nalu outside the submitted work. Members of the EVOKE study group report being employees of Saluda Medical. No other disclosures were reported., (© American Society of Regional Anesthesia & Pain Medicine 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Introduction: Chronic pain patients may experience impairments in multiple health-related domains. The design and interpretation of clinical trials of chronic pain interventions, however, remains primarily focused on treatment effects on pain intensity. This study investigates a novel, multidimensional holistic treatment response to evoked compound action potential-controlled closed-loop versus open-loop spinal cord stimulation as well as the degree of neural activation that produced that treatment response., Methods: Outcome data for pain intensity, physical function, health-related quality of life, sleep quality and emotional function were derived from individual patient level data from the EVOKE multicenter, participant, investigator, and outcome assessor-blinded, parallel-arm randomized controlled trial with 24 month follow-up. Evaluation of holistic treatment response considered whether the baseline score was worse than normative values and whether minimal clinical important differences were reached in each of the domains that were impaired at baseline. A cumulative responder score was calculated to reflect the total minimal clinical important differences accumulated across all domains. Objective neurophysiological data, including spinal cord activation were measured., Results: Patients were randomized to closed-loop (n=67) or open-loop (n=67). A greater proportion of patients with closed-loop spinal cord stimulation (49.3% vs 26.9%) were holistic responders at 24-month follow-up, with at least one minimal clinical important difference in all impaired domains (absolute risk difference: 22.4%, 95% CI 6.4% to 38.4%, p=0.012). The cumulative responder score was significantly greater for closed-loop patients at all time points and resulted in the achievement of more than three additional minimal clinical important differences at 24-month follow-up (mean difference 3.4, 95% CI 1.3 to 5.5, p=0.002). Neural activation was three times more accurate in closed-loop spinal cord stimulation (p<0.001 at all time points)., Conclusion: The results of this study suggest that closed-loop spinal cord stimulation can provide sustained clinically meaningful improvements in multiple domains and provide holistic improvement in the long-term for patients with chronic refractory pain., Trial Registration Number: NCT02924129., Competing Interests: Competing interests: LK reports receiving grants from Nevro, Neuros, Avanos, Medtronic, Neuralace, and Xalud Therapeutics and financial support from Nevro, Avanos, and Saluda Medical. NM reports receiving grants from Neuros and Mesoblast, as well as consulting as a medical monitor for Saluda Medical, Nevro, Vivex, Mainstay, and Vertos. SC reports receiving grants from Saluda Medical, Vertos, Mainstay, and Vivex. CG reports personal fees and other from SPR, and personal fees from Nevro, Nalu, Biotronik, Boston Scientific, Saluda Medical, and Shiratronics. JP serves as a consultant for Abbott, Medtronic, Saluda Medical, Flowonix, SpineThera, Vertos, Vertiflex, SPR Therapeutics, Tersera, Aurora, Spark, Ethos, Biotronik, Mainstay, WISE, Boston Scientific, and Thermaquil; has received grant and research support from: Abbott, Flowonix, Saluda Medical, Aurora, Painteq, Ethos, Muse, Boston Scientific, SPR Therapeutics, Mainstay, Vertos, AIS, and Thermaquil; and is a shareholder of Vertos, SPR Therapeutics, Painteq, Aurora, Spark, Celeri Health, Neural Integrative Solutions, Pacific Research Institute, Thermaquil, and Anesthetic Gas Reclamation. SL reports receiving grants from Avanos, Boston Scientific, Nalu Medical, SPR Therapeutics, Saluda Medical, Averitas Pharma, Biotronik, SGX Therapeutics, and PainTeq, as well as serving as a consultant for Abbott, Avanos, Boston Scientific, Nevro, SPR Therapeutics, Averitas Pharma, Biotronik, Nalu Medical, PainTeq, and Saluda Medical, as well as holding stock options for Nalu Medical. CH has received consultancy fees from Saluda Medical and Genecentrix. PSS has received consultancy fees from Medtronic, Saluda Medical, Nalu, and Biotronic and has stock options from Saluda Medical and Nalu. RST reports consultancy fees from Medtronic, Nevro and Saluda Medical. SE reports consultancy fees from Medtronic, Mainstay Medical, Boston Scientific, and Abbott. He has received department research funding from the National Institute of Health Research, Medtronic and Nevro. JWK is an advisory board member for Boston Scientific, Medtronic, Abbott, and Saluda Medical. ST has received consultancy fees from Boston Scientific, Mainstay Medical, and Saluda Medical. He has received department research funding from the National Institute for Health Research, Boston Scientific, Saluda Medical, and Mainstay Medical. EP has received research support from Mainstay, Medtronic, Neuros Medical, Nevro Corp, ReNeuron, SPR, and Saluda Medical, as well as personal fees from Abbott Neuromodulation, Biotronik, Medtronic Neuromodulation, Nalu, Neuros Medical, Nevro, Presidio Medical, Saluda Medical, and Vertos. She holds stock options from SynerFuse and neuro42. DS is a consultant for Abbott, Medtronic, Nevro, SPR, Vertos, PainTEQ, and Saluda Medical and has received research funding from and holds minority equity in Vertos. TD is a consultant for Abbott, Vertos, SpineThera, Saluda Medical, Cornerloc, SPR Therapeutics, PainTeq, Spinal Simplicity, and Biotronik. He has minor equity in form of stock options for Vertos, Saluda Medical, Cornerloc, Nalu, PainTeq, and Spinal Simplicity, and minor equity in common stock for SpineThera, and Ethos. He is an advisory board member or participates on a data safety monitoring board for Abbott, Vertos, SPR Therapeutics, and Biotronik. AA reports consultancy fees from Boston Scientific. AL, NS and RD are employees of Saluda Medical. RD has previously received consultancy fees from Mainstay Medical, Medtronic Ltd, and Saluda Medical. RL is an uncompensated consultant for Nalu, Saluda Medical, and Mainstay Medical and has stock options from Nalu and Saluda Medical obtained before 2019, not exercisable through the duration of his term as International Neuromodulation Society President and editor-in-chief of the journal Neuromodulation: Technology at the Neural Interface., (© American Society of Regional Anesthesia & Pain Medicine 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Introduction: A novel, spinal cord stimulation (SCS) system with a physiologic closed-loop (CL) feedback mechanism controlled by evoked compound action potentials (ECAPs) enables the optimization of physiologic neural dose and the accuracy of the stimulation, not possible with any other commercially available SCS systems. The report of objective spinal cord measurements is essential to increase the transparency and reproducibility of SCS therapy. Here, we report a cohort of the EVOKE double-blind randomized controlled trial treated with CL-SCS for 36 months to evaluate the ECAP dose and accuracy that sustained the durability of clinical improvements., Methods: 41 patients randomized to CL-SCS remained in their treatment allocation and were followed up through 36 months. Objective neurophysiological data, including measures of spinal cord activation, were analyzed. Pain relief was assessed by determining the proportion of patients with ≥50% and ≥80% reduction in overall back and leg pain., Results: The performance of the feedback loop resulted in high-dose accuracy by keeping the elicited ECAP within 4µV of the target ECAP set on the system across all timepoints. Percent time stimulating above the ECAP threshold was >98%, and the ECAP dose was ≥19.3µV. Most patients obtained ≥50% reduction (83%) and ≥80% reduction (59%) in overall back and leg pain with a sustained response observed in the rates between 3-month and 36-month follow-up (p=0.083 and p=0.405, respectively)., Conclusion: The results suggest that a physiological adherence to supra-ECAP threshold therapy that generates pain inhibition provided by ECAP-controlled CL-SCS leads to durable improvements in pain intensity with no evidence of loss of therapeutic effect through 36-month follow-up., Competing Interests: Competing interests: NM reports personal fees from Saluda Medical for acting as independent medical monitor for the EVOKE study during the conduct of the study; he reports receiving research grants from Neuros, Mesoblast, and Vivex Biologics, as well as consulting as a medical monitor of Nevro, Vivex Biologics, Mainstay, Sollis Therapeutics, and Vertos outside the submitted work. RL is an uncompensated consultant of Biotronik, Abbott, Nalu, Saluda, and Mainstay Medical and has stock options from Nalu and Saluda Medical. TD reports personal fees from Saluda Medical during the conduct of the study and consultancy for Axonics, Abbott, Nalu, Vertos, SpineThera, Mainstay, CornerLoc, Ethos, SPR Therapeutics, Medtronic, Boston Scientific, PainTEQ, Tissue Tech, Spinal Simplicity, and Avanos outside the submitted work. He is a minor equity holder of Saluda Medical, Nalu, SpineThera, Stimgenics, Vertiflex, Vertos, and Bioness and an advisory board member of Abbott, Vertos, Nalu, SPR Therapeutics, and Tissue Tech. LK reports receiving grants from Nevro, Neuros, Avanos, Medtronic, Neuralace, and Xalud Therapeutics and financial support from Nevro, Avanos, and Saluda Medical outside the submitted work. SL reports receiving grants and personal fees from Saluda Medical during the conduct of the study; he reports grants from Avanos, Boston Scientific, Nalu Medical, SPR Therapeutics, Averitas Pharma, Biotronik, SGX Therapeutics, and PainTEQ, as well as consultancy for Abbott, Avanos, Boston Scientific, Nevro, SPR Therapeutics, Averitas Pharma, Biotronik, Nalu Medical, and PainTEQ, outside the submitted work, as well as holding stock options for Nalu Medical. KA reports consultancy for Medtronic, Nevro, Boston Scientific, Nalu, Presidio, Biotronik, Mesoblast, and Vivex Laboratories outside the submitted work. CH reports grants from Saluda Medical during the conduct of the study and consultancy fees from Genecentrix outside the submitted work. SC reports research grants from Saluda Medical to the Cleveland Clinic during the conduct of the study and grants from Vertos, Mainstay, and Vivex outside the submitted work. SMF reports consulting fees from Abbott, Medtronic, Saluda, VertiFlex, Vertos, Surgentec, CornerLoc, Mainstay, and Relievant outside the submitted work; has received grant for research funding from Mainstay, Relievant, Medtronic, Abbott, VertiFlex, Saluda, Nalu, CornerLoc, Aurora, Biotronik, and Stimgenics outside the submitted work; and has an equity position in SynerFuse, Aurora Spine, Thermaquil, SPR Therapeutics, Saluda, CornerLoc, PainTEQ, Stimgenics, Anesthetic Gas Reclamation, Neural Integrative Solutions, SpineThera, and Celeri Health. JP reports research and consulting fees from Saluda Medical during the conduct of the study and consultancy for Abbott, Medtronic, Saluda Medical, Flowonix, SpineThera, Vertos, Vertiflex, SPR Therapeutics, Tersera, Aurora, Spark, Ethos, Biotronik, Mainstay, WISE, Boston Scientific, and Thermaquil outside the submitted work; has received grant and research support from Abbott, Flowonix, Aurora, PainTEQ, Ethos, Muse, Boston Scientific, SPR Therapeutics, Mainstay, Vertos, AIS, and Thermaquil outside the submitted work; and is a shareholder of Vertos, SPR Therapeutics, PainTEQ, Aurora, Spark, Celeri Health, Neural Integrative Solutions, Pacific Research Institute, Thermaquil, and Anesthetic Gas Reclamation. CG reports clinical trial funding from Saluda Medical during the conduct of the study and reports personal fees and others from SPR and personal fees from Nevro, Nalu, Biotronik, and Boston Scientific outside the submitted work. PSS has received consultancy fees from Medtronic, Saluda Medical, Nalu, and Biotronic outside the submitted work and has stock options from Saluda Medical and Nalu. JS reports personal fees from Nevro during the conduct of the study and personal fees from Saluda Medical and Boston Scientific outside the submitted work. TM reports research fees from Saluda Medical during the conduct of the study and personal fees from Nevro outside the submitted work. RR reports grants from SPR, Nalu, and Nevro outside the submitted work, personal fees from Presidio, and grants and personal fees from Boston Scientific and Saluda Medical outside the submitted work. RD, NS, AL, EH, ZO, and DM report being employees of Saluda Medical. LP reports personal fees from Saluda Medical, is a member of the data monitoring board of Saluda Medical during the conduct of the study, and reports personal consulting fees from Medtronic and Nalu outside the submitted work. No other disclosures were reported., (© American Society of Regional Anesthesia & Pain Medicine 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

Aims: To evaluate the long-term efficacy of high-frequency (10 kHz) spinal cord stimulation (SCS) for treating refractory painful diabetic neuropathy (PDN)., Methods: The SENZA-PDN study was a prospective, multicenter, randomized controlled trial that compared conventional medical management (CMM) alone with 10 kHz SCS plus CMM (10 kHz SCS+CMM) in 216 patients with refractory PDN. After 6 months, participants with insufficient pain relief could cross over to the other treatment. In total, 142 patients with a 10 kHz SCS system were followed for 24 months, including 84 initial 10 kHz SCS+CMM recipients and 58 crossovers from CMM alone. Assessments included pain intensity, health-related quality of life (HRQoL), sleep, and neurological function. Investigators assessed neurological function via sensory, reflex, and motor tests. They identified a clinically meaningful improvement relative to the baseline assessment if there was a significant persistent improvement in neurological function that impacted the participant's well-being and was attributable to a neurological finding., Results: At 24 months, 10 kHz SCS reduced pain by a mean of 79.9% compared to baseline, with 90.1% of participants experiencing ≥50% pain relief. Participants had significantly improved HRQoL and sleep, and 65.7% demonstrated clinically meaningful neurological improvement. Five (3.2%) SCS systems were explanted due to infection., Conclusions: Over 24 months, 10 kHz SCS provided durable pain relief and significant improvements in HRQoL and sleep. Furthermore, the majority of participants demonstrated neurological improvement. These long-term data support 10 kHz SCS as a safe and highly effective therapy for PDN., Trial Registration: ClincalTrials.gov Identifier, NCT03228420., Competing Interests: Declaration of competing interest Author Erika A. Petersen has received consulting fees from Abbott Laboratories, Biotronik, Boston Scientific, Medtronic Neuromodulation, Nalu Medical, Neuros Medical, Nevro Corp, Presidio Medical, Saluda, and Vertos Medical, research support from Mainstay, Medtronic Neuromodulation, Nalu Medical, Neuros Medical, Nevro Corp, ReNeuron, Saluda, and SPR, and stock options from neuro42 and SynerFuse. Author Thomas G. Stauss has received research support from Nevro Corp. Author James A. Scowcroft has received research support from Boston Scientific, Nevro Corp, Saluda Medical, and Vertiflex. Author Michael J. Jaasma is an employee of Nevro Corp. Author Elizabeth S. Brooks was an employee of Nevro Corp during her contributions to the work associated with this manuscript. Author Deborah R. Edgar received consulting fees from Nevro in her capacity as an independent medical writer. Author Judith L. White has received consulting fees from California Institute for Biomedical Research and Eli Lilly and research support from Nevro Corp. Author Shawn M. Sills has received research support from Nevro Corp. Author Kasra Amirdelfan has received consulting fees from Biotronik, Medtronic, Nalu Medical, Nevro Corp, and Saluda Medical, as well as research support from Biotronik, IPM Medical Group, Nevro Corp, Saluda Medical, SPR Therapeutics, and Vivex Biologics. Author Maged N. Guirguis has received consulting fees from Abbott Laboratories, Avanos Medical, Avertis Pharmacy, Boston Scientific, Nevro Corp, and Saluda Medical, as well as research support from Abbott Laboratories, Avanos Medical, Boston Scientific, Nalu Medical, Neuros Medical, Nevro Corp, and Saluda Medical. Author Jijun Xu has received research support from the Cleveland Clinic Velosano Program, the National Institutes of Health, the Steve and Melody Golding Foundation, and Nevro Corp. Author Cong Yu has received research support from Nevro Corp. Author Ali Nairizi has received consulting fees from Aurora Spine, Flowonix, and Nevro Corp as well as research support from Nevro Corp. Author Denis G. Patterson has received consulting fees from Abbott Laboratories, AIS Healthcare, Allergan, Amgen, Aurora Spine, CornerLoc, Flowonix, Lundbeck, Pajunk Medical, Saluda Medical, Spark Biomedical, and Vertos Medical, research support from Abbott Laboratories, Aurora Spine, Flowonix, Nevro Corp, and Saluda Medical, speakers’ bureau or honoraria from Abbott Laboratories, Allergan, Amgen, CornerLoc, Lundbeck, Saluda Medical, and Vertos Medical, and stock options from CornerLoc. Author Michael J. Creamer has received research support from Nevro Corp. Author Vincent Galan has received research support from Biotronik, Medtronic, Nevro Corp, PainTEQ, SPR Therapeutics, and St. Jude. Author Richard H. Bundschu has received research support from Nevro Corp. Author Neel D. Mehta has received consulting fees from Averitas, Nevro Corp, and Salix Pharmaceuticals, as well as research support from Boston Scientific and Nevro Corp. Author Dawood Sayed has received consulting fees from Abbott Laboratories, Boston Scientific, Flowonix, Medtronic, Nevro Corp, Vertiflex, and Vertos Medical, as well as research support from Abbott Laboratories, Biotronic, Nevro Corp, Vertiflex, and Vertos Medical. Author Shivanand P. Lad has received consulting fees from Nevro Corp and research support from Nevro Corp. Author David J. DiBenedetto has received research support from Nevro Corp, as well as funding for serving as principal investigator of a study supported by SPR Therapeutics paid to his institution. Author Khalid A. Sethi has received research support from Nevro Corp. Author Johnathan H. Goree has received consulting fees from Abbott Laboratories and Stratus Medical. Author Paul W. Wu has received research support from Nevro Corp. Author Charles E. Argoff has received consulting fees from AbbVie, Amgen, Biohaven, Clexio Biosciences, Collegium, Eli Lilly, Elsevier, Flowonix, Gene Pharma, Lundbeck, Nevro Corp, Novartis, Pfizer, SK Life Science, Teva Pharmaceutical, and Vertex as well as research support from AbbVie, Allergan, Amgen, Daiichi Sankyo, Eli Lilly, Novartis, Teva Pharmaceutical, and Vertex Pharmaceuticals. Author Christian E. Nasr has received consulting fees from Exelixis, Neurogastrx, and Nevro Corp as well as research support from Nevro Corp. Author Rod S. Taylor has received consulting fees from Nevro Corp, Medtronic, and Saluda Medical. Author David L. Caraway is an employee of Nevro Corp. Author Nagy A. Mekhail has received consulting fees from Nevro Corp, Relievant Medsystems, Saluda Medical, Sollis Therapeutics, and Vertos Medical, as well as research support from Avanos Medical, Mesoblast, Neuros Medical, and Nevro Corp., (Copyright © 2023. Published by Elsevier B.V.)

Objective: Spinal cord stimulation (SCS) is considered an effective interventional nonpharmacologic treatment option for several chronic pain conditions. Here we present the effects of the novel evoked compound action potential (ECAP) controlled closed-loop (ECAP-CL) SCS system on long-term sleep quality outcomes from the EVOKE study., Materials and Methods: The EVOKE study is a double-blind, randomized, controlled clinical trial conducted at 13 sites in the United States (N = 134 patients). The clinical trial utilized SCS to manage chronic pain and compared novel ECAP-CL technology to open-loop SCS. Additionally, sleep quality data was collected using the Pittsburgh Sleep Quality Index (PSQI) at baseline and all study visits., Results: The mean PSQI global score for ECAP-CL patients at baseline was 14.0 (n = 62; ± 0.5, SD 3.8), indicating poor sleep quality. Clinically meaningful and statistically significant reductions (p < 0.001) in the global PSQI scores were noted at 12 months (n = 55; 5.7 ± 0.6, SD 4.2). A total of 76.4% of ECAP-CL patients met or exceeded Minimal Clinically Important Difference from baseline in PSQI at 12 months. Additionally, 30.9% of ECAP-CL patients achieved "good sleep quality" scores (PSQI ≤ 5), and 29.1% achieved sleep quality remission. "Normative" sleep scores were observed in 29.6% of ECAP-CL patients at 12 months, and these scores were better than the US general population. Additionally, ECAP-CL patients achieved statistically significant changes from baseline (p < 0.01) across all seven subcomponent scores of PSQI at 12 months., Conclusions: ECAP-CL SCS elicits consistent neural activation of the target leading to less variability in long-term therapy delivery. In the EVOKE study, this resulted in ECAP-CL patients demonstrating clinically superior and sustained pain relief. Results from this study provide new evidence of long-term improvement in sleep quality and quantity in patients with chronic pain resulting from the use of this novel ECAP-CL SCS technology., Clinical Trail Registration: The Clinicaltrials.gov registration number for the study is NCT02924129., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate high-frequency (10-kHz) spinal cord stimulation (SCS) treatment in refractory painful diabetic neuropathy., Patients and Methods: A prospective, multicenter randomized controlled trial was conducted between Aug 28, 2017 and March 16, 2021, comparing conventional medical management (CMM) with 10-kHz SCS+CMM. The participants had hemoglobin A1c level of less than or equal to 10% and pain greater than or equal to 5 of 10 cm on visual analog scale, with painful diabetic neuropathy symptoms 12 months or more refractory to gabapentinoids and at least 1 other analgesic class. Assessments included measures of pain, neurologic function, and health-related quality of life (HRQoL) over 12 months with optional crossover at 6 months., Results: The participants were randomized 1:1 to CMM (n=103) or 10-kHz SCS+CMM (n=113). At 6 months, 77 of 95 (81%) CMM group participants opted for crossover, whereas none of the 10-kHz SCS group participants did so. At 12 months, the mean pain relief from baseline among participants implanted with 10-kHz SCS was 74.3% (95% CI, 70.1-78.5), and 121 of 142 (85%) participants were treatment responders (≥50% pain relief). Treatment with 10-kHz SCS improved HRQoL, including a mean improvement in the EuroQol 5-dimensional questionnaire index score of 0.136 (95% CI, 0.104-0.169). The participants also reported significantly less pain interference with sleep, mood, and daily activities. At 12 months, 131 of 142 (92%) participants were "satisfied" or "very satisfied" with the 10-kHz SCS treatment., Conclusion: The 10-kHz SCS treatment resulted in substantial pain relief and improvement in overall HRQoL 2.5- to 4.5-fold higher than the minimal clinically important difference. The outcomes were durable over 12 months and support 10-kHz SCS treatment in patients with refractory painful diabetic neuropathy., Trial Registration: clincaltrials.gov Identifier: NCT03228420., (© 2022 The Authors.)

Importance: Many patients with diabetic peripheral neuropathy experience chronic pain and inadequate relief despite best available medical treatments., Objective: To determine whether 10-kHz spinal cord stimulation (SCS) improves outcomes for patients with refractory painful diabetic neuropathy (PDN)., Design, Setting, and Participants: The prospective, multicenter, open-label SENZA-PDN randomized clinical trial compared conventional medical management (CMM) with 10-kHz SCS plus CMM. Participants with PDN for 1 year or more refractory to gabapentinoids and at least 1 other analgesic class, lower limb pain intensity of 5 cm or more on a 10-cm visual analogue scale (VAS), body mass index (calculated as weight in kilograms divided by height in meters squared) of 45 or less, hemoglobin A1c (HbA1c) of 10% or less, daily morphine equivalents of 120 mg or less, and medically appropriate for the procedure were recruited from clinic patient populations and digital advertising. Participants were enrolled from multiple sites across the US, including academic centers and community pain clinics, between August 2017 and August 2019 with 6-month follow-up and optional crossover at 6 months. Screening 430 patients resulted in 214 who were excluded or declined participation and 216 who were randomized. At 6-month follow-up, 187 patients were evaluated., Interventions: Implanted medical device delivering 10-kHz SCS., Main Outcomes and Measures: The prespecified primary end point was percentage of participants with 50% pain relief or more on VAS without worsening of baseline neurological deficits at 3 months. Secondary end points were tested hierarchically, as prespecified in the analysis plan. Measures included pain VAS, neurological examination, health-related quality of life (EuroQol Five-Dimension questionnaire), and HbA1c over 6 months., Results: Of 216 randomized patients, 136 (63.0%) were male, and the mean (SD) age was 60.8 (10.7) years. Additionally, the median (interquartile range) duration of diabetes and peripheral neuropathy were 10.9 (6.3-16.4) years and 5.6 (3.0-10.1) years, respectively. The primary end point assessed in the intention-to-treat population was met by 5 of 94 patients in the CMM group (5%) and 75 of 95 patients in the 10-kHz SCS plus CMM group (79%; difference, 73.6%; 95% CI, 64.2-83.0; P < .001). Infections requiring device explant occurred in 2 patients in the 10-kHz SCS plus CMM group (2%). For the CMM group, the mean pain VAS score was 7.0 cm (95% CI, 6.7-7.3) at baseline and 6.9 cm (95% CI, 6.5-7.3) at 6 months. For the 10-kHz SCS plus CMM group, the mean pain VAS score was 7.6 cm (95% CI, 7.3-7.9) at baseline and 1.7 cm (95% CI, 1.3-2.1) at 6 months. Investigators observed neurological examination improvements for 3 of 92 patients in the CMM group (3%) and 52 of 84 in the 10-kHz SCS plus CMM group (62%) at 6 months (difference, 58.6%; 95% CI, 47.6-69.6; P < .001)., Conclusions and Relevance: Substantial pain relief and improved health-related quality of life sustained over 6 months demonstrates 10-kHz SCS can safely and effectively treat patients with refractory PDN., Trial Registration: ClincalTrials.gov Identifier: NCT03228420.

Background: Painful diabetic neuropathy (PDN), a debilitating and progressive chronic pain condition that significantly impacts quality of life, is one of the common complications seen with long-standing diabetes mellitus. Neither pharmacological treatments nor low-frequency spinal cord stimulation (SCS) has provided significant and long-term pain relief for patients with PDN. This study aims to document the value of 10-kHz SCS in addition to conventional medical management (CMM) compared with CMM alone in patients with refractory PDN., Methods: In a prospective, multicenter, randomized controlled trial (SENZA-PDN), 216 subjects with PDN will be assigned 1:1 to receive 10-kHz SCS combined with CMM or CMM alone after appropriate institutional review board approvals and followed for 24 months. Key inclusion criteria include (1) symptoms of PDN for at least 12 months, (2) average pain intensity of at least 5 cm-on a 0- to 10-cm visual analog scale (VAS)-in the lower limbs, and (3) an appropriate candidate for SCS. Key exclusion criteria include (1) large or gangrenous ulcers or (2) average pain intensity of at least 3 cm on VAS in the upper limbs or both. Along with pain VAS, neurological assessments, health-related quality of life, sleep quality, and patient satisfaction will be captured. The primary endpoint comparing responder rates (≥50% pain relief) and safety rates between the treatment groups will be assessed at 3 months. Several secondary endpoints will also be reported on., Discussion: Enrollment commenced in 2017 and was completed in 2019. This study will help to determine whether 10-kHz SCS improves clinical outcomes and health-related quality of life and is a cost-effective treatment for PDN that is refractory to CMM., Trial Registration: ClincalTrials.gov identifier: NCT03228420 (registered 24 July 2017).

Objectives: Spinal cord stimulation is an evidence-based treatment for a number of chronic pain conditions. While this therapy offers improvement in pain and function it is not without potential complications. These complications include device failure, migration, loss of therapeutic paresthesia, and infection. This article looked to establish a modern infection rate for spinal cord stimulators, assess the impact of known risk factors for surgical site infections and to determine the impact of certain preventative measures on the rate of infection., Methods: After institutional review board approval, a multisite, retrospective review was conducted on 2737 unique implants or revisions of SCS systems. Patient demographics, risk factors including diabetes, tobacco use, obesity, revision surgery, trial length, implant location, implant type, surgeon background, prophylactic antibiotic use, utilization of a occlusive dressing, and post-operative antibiotic use were recorded and analyzed., Results: The overall infection rate was 2.45% (n = 67). Diabetes, tobacco use, and obesity did not independently increase the rate of infection. Revision surgeries had a trend toward higher infection rate; however, this did not meet statistical significance. There was no difference in the rate of infection between implants performed by physicians of different base specialties, cylinder leads vs. paddle leads, or between different prophylactic antibiotics. Implants performed at academic centers had a higher rate of infection when compared to implants performed in nonacademic settings. When patients received an occlusive dressing or post-operative antibiotics they had a lower rate of infection., Conclusions: The infection rate (2.45%) reported in this study is lower than the previously reported rates (3-6%) and are on par with other surgical specialties. This study did not show an increased rate of infection for patients that used tobacco, had diabetes or were obese. It's possible that given the low overall infection rate a larger study is needed to establish the true impact of these factors on infection. In addition, this study did not address the impact of poorly controlled diabetes mellitus (elevated hemoglobin A1c) vs. well-controlled diabetes. It can be concluded from this study that utilizing an occlusive dressing over the incision in the post-operative period decreases the rate of infection and should become the standard of care. This study also demonstrated the positive impact of post-operative antibiotics in decreasing the rate of infection. Studies in other surgical specialties have not shown this impact which would suggest that further research is needed., (© 2017 International Neuromodulation Society.)

Introduction: Surgical site infection is a potential complication of spinal cord stimulator (SCS) implantation. Current understanding of the epidemiology, diagnosis, and treatment of these infections is based largely on small clinical studies, many of which are outdated. Evidence-based guidelines for management of SCS-related infections thus rely instead on expert opinion, case reports, and case series. In this study, we aim to provide a large scale retrospective study of infection management techniques specifically for SCS implantation., Methods: A multicenter retrospective study of SCS implants performed over a seven-year period at 11 unique academic and non-academic institutions in the United States. All infections and related complications in this cohort were analyzed., Results: Within our study of 2737 SCS implant procedures, we identified all procedures complicated by infection (2.45%). Localized incisional pain and wound erythema were the most common presenting signs. Laboratory studies were performed in the majority of patients, but an imaging study was performed in less than half of these patients. The most common causative organism was Staphylococcus aureus and the IPG pocket was the most common site of an SCS-related infection. Explantation was ultimately performed in 52 of the 67 patients (77.6%). Non-explantation salvage therapy was attempted in 24 patients and was successful in resolving the infection in 15 patients without removal of SCS hardware components., Discussion: This study provides current data regarding SCS related infections, including incidence, diagnosis, and treatment., (© 2017 International Neuromodulation Society.)

Background: A recent multicenter study presented 52-week safety and efficacy results from an open-label extension of a randomized, sham-controlled trial for patients with chronic migraine (CM) undergoing peripheral nerve stimulation of the occipital nerves. We present the data from a single center of 20 patients enrolled at the Cleveland Clinic's Pain Management Department., Methods: In this single center, 20 patients were implanted with a neurostimulation system, randomized to an active or control group for 12 weeks, and received open-label treatment for an additional 40 weeks. Outcomes collected included number of headache days, pain intensity, Migraine Disability Assessment (MIDAS), Zung Pain and Distress (PAD), direct patient reports of headache pain relief, quality of life, satisfaction, and adverse events (AEs)., Results: Headache days per month were reduced by 8.51 (±9.81) days (P < 0.0001). The proportion of patients who achieved a 30% and 50% reduction in headache days and/or pain intensity was 60% and 35%, respectively. MIDAS and Zung PAD were reduced for all patients. Fifteen (75%) of the 20 patients at the site reported at least one AE. A total of 20 AEs were reported from the site., Conclusion: Our results support the 12-month efficacy of 20 CM patients receiving peripheral nerve stimulation of the occipital nerves in this single-center trial., (© 2016 World Institute of Pain.)

Background: Complex regional pain syndrome (CRPS) is a painful, debilitating affliction that is often difficult to treat. It has become common international practice to use spinal cord stimulation (SCS) for the treatment of CRPS as other therapies fail to provide adequate relief, quality of life, or improvement in function. This comprehensive outcome-specific systematic review of the use of SCS for CRPS was performed to elucidate the available evidence with focus on clinically relevant patient-specific outcomes., Methods: A systematic review of the literature was conducted to evaluate the effects of SCS on patients with CRPS for the following outcomes and provide summary levels of evidence in regard to each outcome: perceived pain relief, pain score, resolution of CRPS signs, functional status, quality of life, psychological impact, sleep hygiene, analgesic medication utilization, and patient satisfaction with SCS therapy. Search terms included "complex regional pain syndrome," "spinal cord stimulation," and "reflex sympathetic dystrophy," without restriction of language, date, or type of publication, albeit only original data were included in analyses. Of 30 studies selected, seven systematic reviews were excluded, as were four studies reporting combination therapy that included SCS and other therapies (ie, concurrent peripheral nerve stimulation, intrathecal therapy) without clear delineation to the effect of SCS alone on outcomes. A total of 19 manuscripts were evaluated., Results: Perceived pain relief, pain score improvement, quality of life, and satisfaction with SCS were all rated 1B+, reflecting positive high-level (randomized controlled trial) evidence favoring SCS use for the treatment of CRPS. Evidence for functional status improvements and psychological effects of SCS was inconclusive, albeit emanating from a randomized controlled trial (evidence level 2B±), and outcomes evidence for both sleep hygiene and resolution of CRPS signs was either nonexistent or of too low quality from which to draw conclusions (evidence level 0). An analgesic sparing effect was observed in nonrandomized reports, reflecting an evidence level of 2C+., Conclusions: Spinal cord stimulation remains a favorable and effective modality for treating CRPS with high-level evidence (1B+) supporting its role in improving CRPS patients' perceived pain relief, pain score, and quality of life. A paucity of evidence for functional improvements, resolution of CRPS signs, sleep hygiene, psychological impact, and analgesic sparing effects mandate further investigation before conclusions can be drawn for these specific outcomes., (© 2016 World Institute of Pain.)

Background: Cervical transforaminal epidural steroid injections (CTFESIs) may help decrease pain and restore function in patients with cervical radiculopathy. Evidence of the injections' effectiveness, however, remains controversial, and multiple case reports have identified potential complications. Such reports have led to diminished interest in including the procedure in patient care algorithms., Objectives: Our retrospective analysis aims to evaluate the CTFESI-associated pain relief and possible decreased need for spine surgery, along with its potential predictive role in determining cervical surgical outcomes. Finally, our study intends to estimate associated complications., Methods: A pain management database registry was used to identify patients who were referred by spine surgeons for diagnostic CTFESIs in preparation for possible surgery between January 2001 and December 2009. Outcomes were defined as the incidence of cervical surgery after diagnostic injection and the associated pain relief. A Poisson distribution was used to obtain a 95% confidence interval for the incidence of complications., Results: Sixty-four patients met the inclusion and exclusion criteria. After diagnostic CTFESIs, 45 (70.3%) of the observed 64 patients did not require cervical spine surgery whereas 19 (29.7%) still did. The mean pain reduction was 4.4 units on the numeric rating scale, with no observed complications., Conclusions: This retrospective analysis further demonstrates the safety, diagnostic value, and possible therapeutic role of CTFESIs. A larger, controlled, randomized study is needed to assess definitively the procedure's efficacy and safety.

Appropriate patient selection and minimizing complications are critical for successful spinal cord stimulation (SCS) therapy in managing intractable pain. We thus reviewed electronic medical records of 707 consecutive cases of patients who received SCS therapy in the Cleveland Clinic from 2000 to 2005 with an emphasis on indications and complications. SCS was used to treat complex regional pain syndrome (CRPS) (345 cases), failed back surgery syndrome (235 cases), peripheral vascular disease (20 cases), visceral pain in the chest, abdomen, and pelvis (37 cases), and peripheral neuropathy (70 cases). CRPS and failed back surgery syndrome accounted for 82% of the cases. The implant-to-trial ratio was 75% on average, with the highest for CRPS type 2 (83%) and the lowest for peripheral vascular diseases (65%). The only documented complication associated with SCS trials was lead migration in 5 of 707 patients (0.7%). There were no permanent neurological deficits or deaths as a result of SCS implant or its complications. Hardware-related complications were common (38%) and included lead migration (22.6%), lead connection failure (9.5%), and lead breakage (6%). Revisions or replacements were required in these cases. Biologically related complications included pain at the generator site (12%) and clinical infection (4.5%; 2.5% with positive culture). The rates of infection varied among the different diagnoses with the highest in failed back surgery syndrome (6.3%). Patients with diabetes had an infection rate of 9%, over the 4% in non-diabetics. Infections were managed successfully with explantation and antibiotic therapy without permanent sequela., (© 2010 World Institute of Pain.)

With the recent technological advances, neurostimulation has provided new hope for millions of patients with debilitating chronic pain conditions that respond poorly to other therapies. Outcome research demonstrated that patients with failed back surgery syndrome and complex regional pain syndromes benefit significantly from neurostimulation in pain reduction, functional capacity, and quality of life. Increasing clinical evidence supports the use of neurostimulation in post-herpetic neuralgia, peripheral neuropathy, occipital neuralgia, and other neuropathic pain conditions. Strong clinical evidences indicate that neurostimulation offers less invasive and more effective therapies for many patients with ischemic pain caused by cardiovascular and peripheral vascular diseases. A growing body of literature supports neurostimulation for visceral pain in general and interstitial cystitis in particular. As a basic principle, patient selection for the appropriate neurostimulation modalities is essential for safe, efficacious, and cost-effective applications of this therapy. Research with more vigorous designs is needed to establish evidence-based applications of neuromodulation therapy in emerging indications of pain management.

Background: A growing number of patients suffer from severe low back pain of discogenic origin that is not responsive to conservative medical management. These patients must consider the option of surgical spinal fusion or minimally-invasive intradiscal electrothermal therapy (IDET)., Objective: To conduct a systematic review of clinical outcomes in patients undergoing spinal fusion or the intradiscal electrothermal therapy (IDET) procedure for intractable discogenic low back pain., Design: Systematic literature review., Methods: English-language journal articles published from January 1995 to December 2005 were identified through computerized searches of the PubMed database and bibliographies of identified articles and review papers. Articles were selected if disc degeneration or disruption was the primary indication for spinal fusion or the IDET procedure and if follow-up outcome data included evaluations of back pain severity, condition-specific functional impairment and/or health-related quality of life. The literature reviewed encompassed 33 spinal fusion articles: 10 randomized controlled trials, 1 nonrandomized controlled trial, 9 before-after trials, and 13 case series. There were 18 IDET articles: 2 randomized controlled trial, 2 nonrandomized controlled trials, 11 before- after trials, and 3 case series. Data were extracted and summarized on patient characteristics, surgical methods, and clinical outcomes., Results: Overall, there were similar median percentage improvements realized after spinal fusion and the IDET procedure, respectively, for 2 of the 3 outcomes evaluated: pain severity (50%, 51%), back function (42%, 14%) and quality of life (46%, 43%). There was an identifiable randomized controlled trials trend of both treatments reporting a smaller magnitude of improvement in all 3 primary outcomes (pain severity, back function, quality of life) compared to other types of trials. Perioperative complications were commonly associated with spinal fusion (median: 14%, range: 2% to 54%, n = 31 study groups) whereas adverse events were rarely experienced with the IDET procedure (median: 0%, range: 0% to 16%, n = 14 studies). Randomized controlled trials of spinal fusion, in particular, had important methodological limitations., Conclusion: The majority of patients reported improvement in symptoms following both spinal fusion and the IDET procedure. The IDET procedure appears to offer sufficiently similar symptom amelioration to spinal fusion without the attendant complications.

Approximately one-third of the American population experiences chronic pain. This varies in origin and severity. It also has been documented that billions of dollars are lost yearly because of health care expenses and missed workdays for chronic pain. Addiction is a primary, chronic, neurobiological disease with genetic, psychological and environmental factors influencing its development and manifestations. Addictive disorders occur in 3% to 26% of the general population, 19% to 255 of hospitalized patients and 40% to 60% in patients who sustained major trauma. More specifically 13.9 million of people living in USA over the age of 12 years are currently using illicit drugs. Although patients with chronic pain may be at an increased risk for addiction, the general population has demonstrated similar addiction rates. Unfortunately, patients who have chronic pain and addition will only have one of these aspects addressed. The purpose of this article is to clarify specific definition of substance use, abuse and addiction. As well as examining the role of pain physicians in evaluating and treating the chronic pain patients who have a history of substance abuse, and lastly outline strategy for assessing patients at risks and evaluating the most practical way of dealing with their chronic pain issues.

Background Context: Epidural steroid injection (ESI) is one of the most common nonsurgical interventions prescribed for back and leg pain symptoms. Although the use of ESI is widespread, proof of efficacy among the broad population of low back pain patients is lacking and use is predicated to a great extent on the cost and morbidity of the perceived "next step" in many patient's care-surgery., Purpose: To review the relative indications and clinical features that predict success with ESI therapy, and to provide a physiological rationale to guide clinical decision-making., Study Design/setting: Review of literature and clinical experience., Results: Clinical studies have alternately supported and refuted the efficacy of ESI in the treatment of patients with back and leg pain. Steroid medications do benefit some patients with radicular pain, but the benefit is often limited in duration, making efficacy difficult to prove over time. Steroids appear to speed the rate of recovery and return to function, however, allowing patients to reduce medication levels and increase activity while awaiting the natural improvement expected in most spinal disorders. Fluoroscopic verification of needle placement, with contrast injection, greatly improves steroid delivery while reducing risks. Although it is assumed that the benefit of steroids is related to their effect on inflammation, that remains unproven, and it is possible that benefit is gained through an unrecognized action., Conclusions: Randomized, controlled trials are needed to conclusively identify those patients most likely to benefit from ESI, and when and for how long. Until then, epidural steroids provide a reasonable alternative to surgical intervention in selected patients with back and/or leg pain, whose symptoms are functionally limiting. When appropriate goals are established and proper patients are selected, sufficient short-term benefit has been documented to warrant continued use of this tool.

Epidural injections of glucocorticoids may help some patients with back and leg pain. The efficacy of this therapy has not been conclusively proved; however, when weighed against the risks, cost, and outcomes of spinal surgery, epidural glucocorticoids are a reasonable alternative in selected patients whose back and leg pain is functionally limiting. We review the rationale, available data, techniques, and indications for these injections.

Objectives: To assess the healthcare utilization of patients with intractable chronic neuropathic pain treated with spinal cord stimulation and peripheral nerve stimulation and to provide a cost-benefit analysis., Methods: The case records of 222 consecutive patients who received spinal cord stimulation or peripheral nerve stimulation implants at the Cleveland Clinic Foundation between 1990 and 1998 were reviewed retrospectively. Patients were asked to complete a Neurostimulation Outcome Questionnaire designed to gather data on utilization of healthcare resources starting 1 year before surgical implantation. These data were pooled and net differences in events per patient per year, before and after device implantation were calculated and modeled to 2000 cost data obtained from the Medicare Fee Schedule and Healthcare Financing Administration., Results: Neurostimulation Outcome Questionnaires were returned by 128 patients. The mean patient age was 46 +/- 12.5 years (range 21-71 years) and the mean implant duration was 3.1 +/- 2.3 years (range 0.5-8.9 years). The mean per patient total reimbursement of spinal cord stimulation/peripheral nerve stimulation absent pharmacotherapy was $38,187. Patients treated with spinal cord stimulation/peripheral nerve stimulation for pain management achieved reductions in physician office visits, nerve blocks, radiologic imaging, emergency department visits, hospitalizations, and surgical procedures, which translated into a net annual savings of approximately $30,221 and a savings of $93,685 over the 3.1-year implant duration. The large reduction in healthcare utilization following spinal cord stimulation/peripheral nerve stimulation implantation resulted in a net per patient per year cost savings of approximately $17,903., Discussion: The reduced demand for healthcare resources by patients receiving neurostimulation suggests that peripheral nerve stimulation and spinal cord stimulation treatment, although associated with relatively high initial costs, demonstrates substantial long-term economic benefits. Thus, neurostimulation should be considered as a viable option for the early treatment of patients with intractable chronic neuropathic pain.

Complex regional pain syndrome (CRPS) is the new nomenclature that encompasses the older diagnostic entities of reflex sympathetic dystrophy (now CRPS 1) and causalgia (CRPS 2). CRPS arises after injuries such as sprains, strains, or fractures, but in some patients the cause is unknown. Although a perennial suspect in the pathogenesis of this entity, the sympathetic nervous system's role in CRPS remains unclear. New studies provide insight into the contribution of the sympathetic nervous system to CRPS and allow reevaluation of clinical features, diagnostic criteria, testing methods, and treatment modalities.

Objective: To increase awareness of the possibility of epidural infection after continuous epidural infusion. Outline the salient diagnostic features of epidural infection. Outline a strategy to manage epidural infection and minimize morbidity., Setting: Academic multidisciplinary pain clinic., Patient: A patient with a left knee meniscal tear with a history of Chronic Regional Pain Syndrome Type I (CRPS I) of the left foot., Interventions: Attempted control of CRPS I symptoms with a tunnelled epidural catheter infusion., Results and Conclusions: The patient developed an epidural abscess diagnosed on the 11th postoperative day. The catheter was removed and the patient was treated successfully with intravenous antibiotics.

Anesthesiologists have become increasingly involved with the management of chronic pain patients in the operating room, on the surgical floor, and in the outpatient pain facility setting (often interdisciplinary). Based upon the authors' practice of regional anesthesia, the most specific contribution to chronic pain management arguably remains the practice of diagnostic, prognostic, and therapeutic injections of the neuraxis, peripheral nerves, and the autonomic nervous system.

Thromboangiitis obliterans (Buerger's disease) is a segmental inflammatory vasculitis that involves the small-sized and medium-sized arteries, veins, and nerves. It is causally related to tobacco use. The diagnosis is usually made on the basis of the presence of distal arterial disease in individuals who smoke and in whom other disease entities have been excluded. The most effective treatment for Buerger's disease is smoking cessation. Without strict adherence to tobacco avoidance, disease progression is likely. Methods to control ischemic pain include medications, sympathectomy, or surgical revascularization. The effect of sympathectomy is unpredictable, and the chances of a successful revascularization procedure are rare because distal target vessels often are extensively diseased. Herein, we describe a patient whose condition did not respond to the usual conservative therapy but did respond dramatically to the implantation of a permanent spinal cord stimulator. Although these devices have been used for more than 20 years in various other peripheral arterial diseases, their use in Buerger's disease has been limited.

The effects of dobutamine (DOB) on myocardial performance, systemic hemodynamics, and oxygen delivery during acute normovolemic hemodilution in anesthetized rats were studied. Forty-two Sprague Dawley rats (body weight 375 to 425 g) were divided into six equal groups. Hemodynamic and cardiac indices were measured or calculated at baseline, 30 minutes after the initiation of hemodilution (HD), and 15 minutes after DOB or saline infusion. Myocardial performance in response to acute pressure or volume loads was studied in all groups of animals. HD to a hematocrit (Hct) value of 20% resulted in no change in heart rate (HR), increased CI, SVI, and LV dP/dt, and decreased MAP, SVRI, and oxygen delivery index (O2DI). HD increased peak SV and CI after preload stress while the left ventricular developed pressure (LVDP) was unchanged. Infusion of DOB as 7.5 or 15 micrograms/kg/min increased HR, CI, and LV dP/dt as well as LVDP. At the same time, DOB decreased MAP and SVR, whereas the SVI remained unchanged. In non-HD animals both doses of DOB increased LVDP, but only the larger dose increased CI, whereas peak SV decreased with the smaller dose. Arterial carbon dioxide tension (PaCO2) increased, whereas pH and arterial oxygen tension (PaO2) decreased; however, O2DI remained unchanged. Concomitant hemodilution and DOB infusion resulted in attenuation of HR response to DOB, exaggerated the drop in MAP and SVR, and increased LV dP/dt. Only the larger dose of DOB increased the CI, whereas neither dose could alter the SVI in HD animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of fentanyl on ultrastructure, protein biosynthesis, and atrial natriuretic peptide (ANP) secretion were studied in neonatal rat cardiomyocytes (CM). Ventricles from 2-day-old American Wistar rats were digested with 1% collagenase in perfusion buffer. Eight hundred thousand to 1.0 million cells/ml were incubated in tissue culture media, to which fentanyl citrate (Sublimaze) was added in a dose of 10-50 ng/ml. Fentanyl increased the spontaneous CM beating rate, which became rather fibrillary in nature. Protein biosynthesis also increased in a time-related manner. Simultaneous incubation with naloxone (10(-6) M) did not alter the beating rate or protein synthesis. Ultrastructurally, several criteria of myocyte growth were observed: an increase in myofilaments and the appearance of newly formed organized sarcomeres, which were preceded by an increase in the ribosomes and cisternae of rough endoplasmic reticulum, and the appearance of large, adult-type mitochondria with increased matrix granules and long parallel cristae. The latter replaced the elongated thin fetal mitochondria. This was associated with a network of developing sarcoplasmic reticulum and T-tubular system as well as the formation of intercalated discs between the CM. Furthermore, exposure to fentanyl increased ANP immunoreactivity in the culture media while simultaneous incubation with naloxone blocked the effect of fentanyl on ANP secretion. On the other hand, naloxone alone did not alter ANP secretion. Therefore, it could be concluded that fentanyl stimulated protein biosynthesis and ANP secretion as evidenced both biochemically and ultrastructurally. Although the molecular mechanism of ANP secretion by fentanyl is still unclear, yet an opioid receptor mediation could be possible as ANP secretion was blocked by an opioid receptor antagonist (naloxone).

The cardiovascular actions of cocaine in vivo are varied and often antagonistic. Cocaine produces excitatory sympathomimetic effects by interfering with re-uptake of norepinephrine at adrenergic nerve terminals. However, the local anaesthetic properties of cocaine exert depressant effects on the myocardium. In an attempt to differentiate the direct effects of cocaine from the indirect sympathomimetic effects on the myocardium, primary cultures of neonatal rat cardiomyocytes were established under serum-free conditions and exposed to cocaine and/or norepinephrine. After 36-48 h in culture, spontaneously contracting cells were treated with cocaine (10-1,000 micrograms/ml) and contractile rate (beats/min) quantitated, after which the cells were processed for ultrastructural examination. The contractile rate was reduced at all dosages with nearly 80% reduction at the highest concentration studied. Recovery of beating rate was observed 24 h after removal of cocaine. Pronounced cytoplasmic vacuolation of the cells occurred at concentrations > or = 100 micrograms/ml. Ultrastructural examination revealed extensive myofibrillar disruption, membrane damage, and a near complete loss of organized sarcomeres. Nuclear morphology remained unaffected. Within 24 h after removal of cocaine from the medium, myocytes recovered their characteristic cytoplasmic architecture, indicative of sarcomere reassembly. The results observed in response to cocaine were distinctly different from the response to norepinephrine. In these myocytes, the contractile rate was enhanced twofold and morphological damage was not observed. These findings suggest that cocaine can directly alter myocardial morphology independent of its sympathomimetic effects.

The presence of cholecystokinin (CCK) immunoreactive nerve fibres in the rat ovary and uterine tubes was detected using the peroxidase antiperoxidase (PAP) technique. The antibody used was anti CCK 4562 which reacts with CCK-4, CCK-8, CCK-12 and CCK-33 (Larsson and Rehfeld, 1977). CCK-immunoreactive nerve fibres were found between the interstitial cells of the ovary, along blood vessels, and close to smooth muscle fibres in the ovary and tubal wall. A possible role of CCK-nerves in modulation of the sensitivity of the ovarian components to other humoral and nervous stimuli is discussed. The possible control of CCK over smooth muscle fibres in the ovary and the uterine tube and its role in ovulation is a matter of further studies.

The fine structure of intraganglionic blood vessels of rat superior cervical sympathetic ganglia is studied with the light microscope and with both conventional and ultrastructural histochemical methods. Two sets of small capillaries together with larger sinusoidal ones are identified. One set of capillaries is associated with the clustered (type II) small catecholamine-containing (CC) cells and exhibits features suggestive of fluid transport function (multiple wide fenestrae and active pinocytosis). The second set of capillaries is in direct relation to the sympathetic neurons (SN) and shows characteristics suggestive of absorptive function (microvilli and pinocytotic vesicles). The larger sinusoidal capillaries are observed in the vicinity of type II CC cells, extend parallel to the long axes of the perikarya of the neurons and occasionally form loops around them. The latter are assumed to be larger blood spaces connecting the two capillary sets and serve to slow the circulation around the neurons. A pattern of portal-like intraganglionic microcirculation through which type II CC cells participate in modulating the SN is postulated. Type II CC cells secrete a catecholamine modulator which, driven by concentration gradient, gains access to the circulation through the fenestrated capillaries. The sinusoidal capillaries serve to perfuse the SN with a slow stream of blood rich in the catecholamine modulator. The latter can be filtered through the microvilli and pinocytotic vesicles of the second set of capillaries to induce slow inhibitory postsynaptic potential on the SN.

The synapses of the rat superior cervical sympathetic ganglion were studied with both conventional and ultrastructural histochemical methods. Besides the cholinergic synapses polarized from preganglionic fibers to sympathetic ganglion neurons, two morphologically and functionally different types of synapses were observed in relation to the small granule-containing (catecholamine-containing) cells of the rat superior cervical ganglion. The first type is an efferent adrenergic synapse polarized from granule-containing cells to the dendrites of the sympathetic ganglion neurons. This type of synapse might mediate the inhibitory effects (slow inhibitory postsynaptic potentials) induced by catecholamines on the sympathetic neurons. The second type is a reciprocal type of synapse between the granule-containing cells and the cholinergic preganglionic fibers. Through such synapses, these cells could exert a modulating effect on the excitatory preganglionic fibers. Therefore, we propose that these cells, through their multiple synaptic connections, exhibit a local modulatory feedback system in the rat sympathetic ganglia and may serve as interneurons between the preganglionic and postganglionic sympathetic neurons.

The ultrastructural effects of long-term propranolol administration on the catecholamine-containing (CC) cells of cervical sympathetic ganglia were studied in spontaneously hypertensive rats. After 2 months of propranolol administration, there were hydrops of mitochondria, together with swelling and vesiculation of Golgi complex and rough endoplasmic reticulum. Such swollen organelles seemed to coalesce with each other, resulting in transformation of major parts of the cytoplasm into large membrane bound saccules. In that group of animals, the number of CC vesicles showed a significant decrease (P less than 0.025) compared to the control. Moreover, such vesicles looked more electron dense, with decreased electron-lucent haloes compared to the control. Blood pressure recording via rat tail cuff showed a significant drop (P less than 0.0001) of the mean systolic blood pressure in the treated animals. One month after stopping propranolol administration, resorption of the cytoplasmic saccules occurred, but the cytoplasm looked lighter and lost its granular appearance. The mitochondria regained their normal shape, though they appeared fewer in number. The CC vesicles were significantly reduced in number (P less than 0.001) and were less electron dense compared to the control. The possible implications of these findings on the mechanism of action of propranolol as an antihypertensive agent are discussed.