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Muller L, Pope J, Verrills P, Petersen E, Kallewaard JW, Gould I, Karantonis DM. First evidence of a biomarker-based dose-response relationship in chronic pain using physiological closed-loop spinal cord stimulation. Reg Anesth Pain Med 2024:rapm-2024-105346. [PMID: 38508591 DOI: 10.1136/rapm-2024-105346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 02/28/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND AND OBJECTIVES In spinal cord stimulation (SCS) therapy, electricity is the medication delivered to the spinal cord for pain relief. In contrast to conventional medication where dose is determined by desired therapeutic plasma concentration, there is lack of equivalent means of determining dose delivery in SCS. In open-loop (OL) SCS, due to the dynamic nature of the epidural space, the activating electric field delivered is inconsistent at the level of the dorsal columns. Recent Food and Drug Administration guidance suggests accurate and consistent therapy delivered using physiologic closed-loop control (PCLC) devices can minimize underdosage or overdosage and enhance medical care. PCLC-based evoked compound action potential (ECAP)-controlled technology provides the ability to prescribe a precise stimulation dose unique to each patient, continuously measure neural activation, and objectively inform SCS therapy optimization. METHODS Neurophysiological indicator metrics of therapy dose, usage above neural activation threshold, and accuracy of SCS therapy were assessed for relationship with pain reduction in over 600 SCS patients. RESULTS Significant relationships between objective metrics and pain relief across the patient population are shown, including first evidence for a dose-response relationship in SCS. CONCLUSIONS Higher dose, more time over ECAP threshold, and higher accuracy are associated with better outcomes across patients. There is potential to optimize individual patient outcomes based on unique objective measurable electrophysiological inputs.
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Affiliation(s)
- Leah Muller
- Saluda Medical US, Bloomington, Minnesota, USA
| | - Jason Pope
- Evolve Restorative Center, Santa Rosa, California, USA
| | | | - Erika Petersen
- University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | | | - Ian Gould
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
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Mekhail NA, Levy RM, Deer TR, Kapural L, Li S, Amirdelfan K, Hunter CW, Rosen SM, Costandi SJ, Falowski SM, Burgher AH, Pope JE, Gilmore CA, Qureshi FA, Staats PS, Scowcroft J, McJunkin T, Kim CK, Yang MI, Stauss T, Rauck R, Duarte RV, Soliday N, Leitner A, Hanson E, Ouyang Z, Mugan D, Poree L. Neurophysiological outcomes that sustained clinically significant improvements over 3 years of physiologic ECAP-controlled closed-loop spinal cord stimulation for the treatment of chronic pain. Reg Anesth Pain Med 2024:rapm-2024-105370. [PMID: 38490687 DOI: 10.1136/rapm-2024-105370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 03/17/2024]
Abstract
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.
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Affiliation(s)
- Nagy A Mekhail
- Evidence-Based Pain Management Research, Cleveland Clinic, Cleveland, Ohio, USA
| | - Robert M Levy
- Anesthesia Pain Care Consultants, Boca Raton, Florida, USA
| | - Timothy R Deer
- Spine and Nerve Center of the Virginias, Charleston, West Virginia, USA
| | | | - Sean Li
- National Spine and Pain Centers, Shrewsbury, New Jersey, USA
| | - Kasra Amirdelfan
- Integrated Pain Management Medical Group Inc, Walnut Creek, California, USA
| | - Corey W Hunter
- Ainsworth Institute of Pain Management, New York, New York, USA
| | - Steven M Rosen
- Delaware Valley Pain and Spine Institute, Trevose, Pennsylvania, USA
| | - Shrif J Costandi
- Evidence-Based Pain Management Research, Cleveland Clinic, Cleveland, Ohio, USA
| | - Steven M Falowski
- Argires-Marotti Neurosurgical Associates of Lancaster, Lancaster, Pennsylvania, USA
| | | | - Jason E Pope
- Evolve Restorative Center, Santa Rosa, California, USA
| | | | | | - Peter S Staats
- National Spine and Pain Centers, Shrewsbury, New Jersey, USA
| | | | | | - Christopher K Kim
- Spine and Nerve Center of the Virginias, Charleston, West Virginia, USA
| | | | - Thomas Stauss
- Pain Physicians of Wisconsin, Milwaukee, Wisconsin, USA
| | - Richard Rauck
- Carolinas Pain Institute, Winston-Salem, North Carolina, USA
| | - Rui V Duarte
- Department of Health Data Science, University of Liverpool, Liverpool, UK
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Nicole Soliday
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Angela Leitner
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Erin Hanson
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Zhonghua Ouyang
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Dave Mugan
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Lawrence Poree
- University of California San Francisco, San Francisco, California, USA
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Versantvoort EM, Dietz BE, Mugan D, Vuong QC, Luli S, Obara I. Evoked compound action potential (ECAP)-controlled closed-loop spinal cord stimulation in an experimental model of neuropathic pain in rats. Bioelectron Med 2024; 10:2. [PMID: 38195618 PMCID: PMC10777641 DOI: 10.1186/s42234-023-00134-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/29/2023] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Preclinical models of spinal cord stimulation (SCS) are lacking objective measurements to inform translationally applicable SCS parameters. The evoked compound action potential (ECAP) represents a measure of dorsal column fiber activation. This measure approximates the onset of SCS-induced sensations in humans and provides effective analgesia when used with ECAP-controlled closed-loop (CL)-SCS systems. Therefore, ECAPs may provide an objective surrogate for SCS dose in preclinical models that may support better understanding of SCS mechanisms and further translations to the clinics. This study assessed, for the first time, the feasibility of recording ECAPs and applying ECAP-controlled CL-SCS in freely behaving rats subjected to an experimental model of neuropathic pain. METHODS Adult male Sprague-Dawley rats (200-300 g) were subjected to spared nerve injury (SNI). A custom-made six-contact lead was implanted epidurally covering T11-L3, as confirmed by computed tomography or X-ray. A specially designed multi-channel system was used to record ECAPs and to apply ECAP-controlled CL-SCS for 30 min at 50 Hz 200 µs. The responses of dorsal column fibers to SCS were characterized and sensitivity towards mechanical and cold stimuli were assessed to determine analgesic effects from ECAP-controlled CL-SCS. Comparisons between SNI rats and their controls as well as between stimulation parameters were made using omnibus analysis of variance (ANOVA) tests and t-tests. RESULTS The recorded ECAPs showed the characteristic triphasic morphology and the ECAP amplitude (mV) increased as higher currents (mA) were applied in both SNI animals and controls (SNI SCS-ON and sham SCS-ON). Importantly, the use of ECAP-based SCS dose, implemented in ECAP-controlled CL-SCS, significantly reduced mechanical and cold hypersensitivity in SNI SCS-ON animals through the constant and controlled activation of dorsal column fibers. An analysis of conduction velocities of the evoked signals confirmed the involvement of large, myelinated fibers. CONCLUSIONS The use of ECAP-based SCS dose implemented in ECAP-controlled CL-SCS produced analgesia in animals subjected to an experimental model of neuropathic pain. This approach may offer a better method for translating SCS parameters between species that will improve understanding of the mechanisms of SCS action to further advance future clinical applications.
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Affiliation(s)
- Eline M Versantvoort
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
| | - Birte E Dietz
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Saluda Medical Europe Ltd, Harrogate, HG2 8NB, UK
| | - Dave Mugan
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Saluda Medical Europe Ltd, Harrogate, HG2 8NB, UK
| | - Quoc C Vuong
- Bioscience Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
| | - Saimir Luli
- Preclinical In Vivo Imaging, Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE2 4HH, UK
| | - Ilona Obara
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK.
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK.
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Single PS, Scott JB, Mugan D. Measures of Dosage for Spinal-Cord Electrical Stimulation: Review and Proposal. IEEE Trans Neural Syst Rehabil Eng 2023; 31:4653-4660. [PMID: 37983153 DOI: 10.1109/tnsre.2023.3335100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
This manuscript proposes an electrical definition of therapeutic dose for spinal-cord systems used for the treatment of chronic pain, analogous to the pharmacological definition. Dose-response relationships are fundamental to pharmacology, radio-therapy, and other treatments, but have never been properly established for neuromodulation. This manuscript offers a robust measure of dose, pre-requisite to establishing a reliable and repeatable dose-response relationship. The new definition, enabled by the system transresistance obtained from measurement of evoked action potentials, recognizes the mechanism of action of spinal cord stimulation (SCS), and should improve acceptance of the therapy as compared to pharmacological treatments which are currently used more frequently for the treatment of chronic pain. The new definition suggests methods for personalization and standardization of the dose in SCS, and is potentially generalizable to all neuromodulation therapies in which nervous tissue is excited including sacral nerve stimulation (SNS), vagal nerve stimulation (VNS) and deep-brain stimulation (DBS). Formulas are provided, and applied using patient data. Powerful conclusions are drawn from application of the new measure.
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Nijhuis HJA, Hofsté WJ, Krabbenbos IP, Dietz BE, Mugan D, Huygen F. First Report on Real-World Outcomes with Evoked Compound Action Potential (ECAP)-Controlled Closed-Loop Spinal Cord Stimulation for Treatment of Chronic Pain. Pain Ther 2023; 12:1221-1233. [PMID: 37481774 PMCID: PMC10444915 DOI: 10.1007/s40122-023-00540-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/30/2023] [Indexed: 07/25/2023] Open
Abstract
INTRODUCTION A novel closed-loop spinal cord stimulation (SCS) system has recently been approved for use which records evoked compound action potentials (ECAPs) from the spinal cord and utilizes these recordings to automatically adjust the stimulation strength in real time. It automatically compensates for fluctuations in distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a determined target level. This data collection was principally designed to evaluate the performance of this first closed-loop SCS system in a 'real-world' setting under normal conditions of use in a single European center. METHODS In this prospective, single-center observational data collection, 22 patients were recruited at the outpatient pain clinic of the St. Antonius Hospital. All candidates were suffering from chronic pain in the trunk and/or limbs due to PSPS type 2 (persistent spinal pain syndrome). As standard of care, follow-up visits were completed at 3 months, 6 months, and 12 months post-device activation. Patient-reported outcome data (pain intensity, patient satisfaction) and electrophysiological and device data (ECAP amplitude, conduction velocity, current output, pulse width, frequency, usage), and patient interaction with their controller were collected at baseline and during standard of care follow-up visits. RESULTS Significant decreases in pain intensity for overall back or leg pain scores (verbal numerical rating score = VNRS) were observed between baseline [mean ± SEM (standard error of the mean); n = 22; 8.4 ± 0.2)], 3 months (n = 12; 1.9 ± 0.5), 6 months (n = 16; 2.6 ± 0.5), and 12 months (n = 20; 2.0 ± 0.5), with 85.0% of the patients being satisfied at 12 months. Additionally, no significant differences in average pain relief at 3 months and 12 months between the real-world data (77.2%; 76.8%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies were observed. CONCLUSIONS These initial 'real-world' data on ECAP-controlled, closed-loop SCS in a real-world clinical setting appear to be promising, as they provide novel insights of the beneficial effect of ECAP-controlled, closed-loop SCS in a real-world setting. The presented results demonstrate a noteworthy maintenance of pain relief over 12 months and corroborate the outcomes observed in the AVALON prospective, multicenter, single-arm study and the EVOKE double-blind, multicenter, randomized controlled trial. TRIAL REGISTRATION The data collection is registered on the International Clinical Trials Registry Platform (Trial NL7889).
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Affiliation(s)
- Harold J. A. Nijhuis
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
- Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Willem-Jan Hofsté
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
| | - Imre P. Krabbenbos
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
| | | | - Dave Mugan
- Saluda Medical Europe Ltd, Harrogate, United Kingdom
| | - Frank Huygen
- Erasmus University Medical Center, Rotterdam, The Netherlands
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Brucker-Hahn MK, Zander HJ, Will AJ, Vallabh JC, Wolff JS, Dinsmoor DA, Lempka SF. Evoked compound action potentials during spinal cord stimulation: effects of posture and pulse width on signal features and neural activation within the spinal cord. J Neural Eng 2023; 20:046028. [PMID: 37531954 DOI: 10.1088/1741-2552/aceca4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/01/2023] [Indexed: 08/04/2023]
Abstract
Objective.Evoked compound action potential (ECAP) recordings have emerged as a quantitative measure of the neural response during spinal cord stimulation (SCS) to treat pain. However, utilization of ECAP recordings to optimize stimulation efficacy requires an understanding of the factors influencing these recordings and their relationship to the underlying neural activation.Approach.We acquired a library of ECAP recordings from 56 patients over a wide assortment of postures and stimulation parameters, and then processed these signals to quantify several aspects of these recordings (e.g., ECAP threshold (ET), amplitude, latency, growth rate). We compared our experimental findings against a computational model that examined the effect of variable distances between the spinal cord and the SCS electrodes.Main results.Postural shifts strongly influenced the experimental ECAP recordings, with a 65.7% lower ET and 178.5% higher growth rate when supine versus seated. The computational model exhibited similar trends, with a 71.9% lower ET and 231.5% higher growth rate for a 2.0 mm cerebrospinal fluid (CSF) layer (representing a supine posture) versus a 4.4 mm CSF layer (representing a prone posture). Furthermore, the computational model demonstrated that constant ECAP amplitudes may not equate to a constant degree of neural activation.Significance.These results demonstrate large variability across all ECAP metrics and the inability of a constant ECAP amplitude to provide constant neural activation. These results are critical to improve the delivery, efficacy, and robustness of clinical SCS technologies utilizing these ECAP recordings to provide closed-loop stimulation.
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Affiliation(s)
- Meagan K Brucker-Hahn
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Hans J Zander
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Andrew J Will
- Twin Cities Pain Clinic, Edina, MN, United States of America
| | - Jayesh C Vallabh
- Ohio State Wexner Medical Center, Columbus, OH, United States of America
| | - Jason S Wolff
- iSpine Clinics, Maple Grove, MN, United States of America
| | | | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, United States of America
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Leitner A, Hanson E, Soliday N, Staats P, Levy R, Pope J, Kallewaard JW, Doleys D, Li S, Weisbein J, Amirdelfan K, Poree L. Real World Clinical Utility of Neurophysiological Measurement Utilizing Closed-Loop Spinal Cord Stimulation in a Chronic Pain Population: The ECAP Study Protocol. J Pain Res 2023; 16:2497-2507. [PMID: 37497371 PMCID: PMC10368120 DOI: 10.2147/jpr.s411927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023] Open
Abstract
Background Spinal cord stimulation (SCS) is an established chronic pain treatment, but the effectiveness of traditional, open-loop paradigms has been plagued by variable sustainability in a real-world setting. A new approach, utilizing evoked compound action potential (ECAP) controlled closed-loop (CL) SCS, continuously monitors spinal cord activation and automatically adjusts the stimulation amplitude of every pulse, maintaining stimulation at the prescribed ECAP level through this continual feedback mechanism. Recent studies demonstrated the long-term safety and efficacy of ECAP-controlled CL-SCS. Here, we report the design of a prospective, multicenter, single-arm feasibility study to characterize clinical outcomes in a real-world chronic pain population utilizing ECAP-controlled CL-SCS. Objective neurophysiological measurements such as device performance and patient therapy compliance, will be analyzed against baseline biopsychosocial assessments, to explore the clinical utility of these objective physiologic biomarkers in patient phenotyping. Methods This study will enroll up to 300 subjects with chronic, intractable trunk and/or limb pain in up to 25 United States investigation sites. Subjects meeting eligibility criteria will undergo a trial procedure and a permanent implant following a successful trial. Neurophysiological measurements (measured in-clinic and continuously during home use) and clinical outcomes including pain, quality-of-life, psychological, emotional, and functional assessments will be collected at baseline, trial end, and up to 24-months post-implantation. Discussion Associations between objective neurophysiological data, clinical evaluation and patient-reported outcomes may have important clinical and scientific implications. They may provide novel insights about the chronic pain pathophysiology, its modulation during CL-SCS, and identification of pain phenotypes and/or mechanisms associated with treatment response during SCS trials and long-term therapy. Data from the ECAP study could lead to improvements in diagnosis, assessment, patient identification and management of chronic pain. It could also provide the foundation for development of a new SCS treatment approach customized by the patient's pain phenotype, unique neurophysiology, and disease severity.
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Affiliation(s)
- Angela Leitner
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Erin Hanson
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Nicole Soliday
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Peter Staats
- National Spine and Pain Centers, Shrewsbury, NJ, USA
| | - Robert Levy
- Departments of Neurosurgery and Clinical Research, Anesthesia Pain Care Consultants, Tamarac, FL, USA
| | - Jason Pope
- Evolve Restorative Center, Santa Rosa, CA, USA
| | - Jan W Kallewaard
- Department of Anaesthesiology and Pain Management, Rijnstate Hospital, Arnhem, the Netherlands
- Department of Anesthesiology and Pain Medicine, Amsterdam University Medical Centre, Amsterdam, the Netherlands
| | - Daniel Doleys
- Pain and Rehabilitation Institute, Birmingham, AL, USA
| | - Sean Li
- National Spine and Pain Centers, Shrewsbury, NJ, USA
| | | | | | - Lawrence Poree
- Department of Anesthesia and Perioperative Care, University of California at San Francisco, San Francisco, CA, USA
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Strand N, J M, Tieppo Francio V, M M, Turkiewicz M, El Helou A, M M, S C, N S, J P, C W. Advances in Pain Medicine: a Review of New Technologies. Curr Pain Headache Rep 2022; 26:605-616. [PMID: 35904729 PMCID: PMC9334973 DOI: 10.1007/s11916-022-01062-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2022] [Indexed: 11/25/2022]
Abstract
Purpose of Review This narrative review highlights the interventional musculoskeletal techniques that have evolved in recent years. Recent Findings The recent progress in pain medicine technologies presented here represents the ideal treatment of the pain patient which is to provide personalized care. Advances in pain physiology research and pain management technologies support each other concurrently. Summary As new technologies give rise to new perspectives and understanding of pain, new research inspires the development of new technologies
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Affiliation(s)
- Natalie Strand
- Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Phoenix, AZ, USA. .,NorthShore University HealthSystem, Evanston, IL, USA. .,University of Chicago Medicine, Chicago, IL, USA.
| | - Maloney J
- Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Phoenix, AZ, USA
| | - Vinicius Tieppo Francio
- Department of Rehabilitation Medicine, The University of Kansas Medical Center (KUMC), 3901 Rainbow Blvd. MS1046, Kansas City, KS, 66160, USA
| | - Murphy M
- Department of Rehabilitation Medicine, The University of Kansas Medical Center (KUMC), 3901 Rainbow Blvd. MS1046, Kansas City, KS, 66160, USA
| | | | - Antonios El Helou
- Department of Neurosurgery, The Moncton Hospital, Moncton, NB, Canada
| | - Maita M
- Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Phoenix, AZ, USA
| | - Covington S
- Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Phoenix, AZ, USA
| | - Singh N
- OrthoAlabama Spine and Sports, Birmingham, AL, USA
| | - Peck J
- Performing Arts Medicine Department, Shenandoah University, Winchester, VA, USA
| | - Wie C
- Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Phoenix, AZ, USA
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9
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Closed-Loop Systems in Neuromodulation. Neurosurg Clin N Am 2022; 33:297-303. [DOI: 10.1016/j.nec.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Fan W, Sullivan SJ, Sdrulla AD. Dorsal Column and Root Stimulation at Aβ-fiber Intensity Activate Superficial Dorsal Horn Glutamatergic and GABAergic Populations. Mol Pain 2022; 18:17448069221079559. [PMID: 35088625 PMCID: PMC8891844 DOI: 10.1177/17448069221079559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Neurostimulation therapies are frequently used in patients with chronic pain conditions. They emerged from Gate Control Theory (GCT), which posits that Aβ-fiber activation recruits superficial dorsal horn (SDH) inhibitory networks to “close the gate” on nociceptive transmission, resulting in pain relief. However, the efficacy of current therapies is limited, and the underlying circuits remain poorly understood. For example, it remains unknown whether ongoing stimulation of Aβ-fibers is sufficient to drive activity in SDH neurons. We used multiphoton microscopy in spinal cords extracted from mice expressing the genetically encoded calcium indicator GCaMP6s in glutamatergic and GABAergic populations; activity levels were inferred from deconvolved calcium signals using CaImAn software. Sustained Aβ-fiber stimulation at the dorsal columns or dorsal roots drove robust yet transient activation of both SDH populations. Following the initial increase, activity levels decreased below baseline in glutamatergic neurons and were depressed after stimulation ceased in both populations. Surprisingly, only about half of GABAergic neurons responded to Aβ-fiber stimulation. This subset showed elevated activity for the entire duration of stimulation, while non-responders decreased with time. Our findings suggest that Aβ-fiber stimulation initially recruits both excitatory and inhibitory populations but has divergent effects on their activity, providing a foundation for understanding the analgesic effects of neurostimulation devices. Perspective: This article used microscopy to characterize the responses of mouse spinal cord cells to stimulation of non-painful nerve fibers. These findings deepen our understanding of how the spinal cord processes information and provide a foundation for improving pain-relieving therapies.
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Affiliation(s)
- Wei Fan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Steve J Sullivan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Andrei D Sdrulla
- Anesthesiology and Pain Management6684Oregon Health & Science University
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11
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Malinowski MN, Chopra PR, Tieppo Francio V, Budwany R, Deer TR. A narrative review and future considerations of spinal cord stimulation, dorsal root ganglion stimulation and peripheral nerve stimulation. Curr Opin Anaesthesiol 2021; 34:774-780. [PMID: 34608057 DOI: 10.1097/aco.0000000000001072] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW In recent years, neuromodulation has experienced a renaissance. Novel waveforms and anatomic targets show potential improvements in therapy that may signify substantial benefits. New innovations in peripheral nerve stimulation and dorsal root ganglion stimulation have shown prospective evidence and sustainability of results. Sub-perception physiologic bursting, high-frequency stimulation and feedback loop mechanisms provide significant benefits over traditional tonic spinal cords stimulation (SCS) in peer reviewed investigations. We reviewed the themes associated with novel technology in the context of historical stalwart publications. RECENT FINDINGS New innovations have led to better nerve targeting, improvements in disease-based treatment, and opioid alternatives for those in chronic pain. In addition, new neural targets from both structural and cellular perspectives have changed the field of Neurostimulation. SUMMARY For many years, tonic SCS was representative of neuromodulation, but as this review examines, the progression of the field in the past decade has reshaped patient options.
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Affiliation(s)
- Mark N Malinowski
- OhioHealth Grant Medical Center, Ohio University Heritage COM, Columbus, Ohio
| | | | - Vinicius Tieppo Francio
- The University of Kansas Medical Center, Department of Rehabilitative Medicine, Kansas City, Kansas
| | - Ryan Budwany
- Center for Integrative Pain Management, West Virginia University School of Medicine, Morgantown
| | - Timothy Ray Deer
- The Spine and Nerve Center of The Virginias
- Anesthesiology and Pain Medicine, WVU School of Medicine
- American Society of Pain and Neuroscience, Charleston, West Virginia, USA
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12
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Dietz BE, Mugan D, Vuong QC, Obara I. Electrically Evoked Compound Action Potentials in Spinal Cord Stimulation: Implications for Preclinical Research Models. Neuromodulation 2021; 25:64-74. [PMID: 34224656 DOI: 10.1111/ner.13480] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/05/2021] [Accepted: 05/17/2021] [Indexed: 01/26/2023]
Abstract
OBJECTIVES The study aimed to assess the feasibility of recording electrically evoked compound action potentials (ECAPs) from the rat spinal cord. To achieve this, we characterized electrophysiological responses of dorsal column (DC) axons from electrical stimulation and quantified the relationship between ECAP and motor thresholds (ECAPTs and MTs). MATERIAL AND METHODS Naïve, anesthetized and freely behaving rats were implanted with a custom-made epidural spinal cord stimulation (SCS) lead. Epidural stimulation and recordings were performed on the same lead using specifically designed equipment. RESULTS The ECAPs recorded from the rat spinal cord demonstrated the expected triphasic morphology. Using 20 μsec pulse duration and 2 Hz frequency rate, the current required in anesthetized rats to generate ECAPs was 0.13 ± 0.02 mA, while the average current required to observe MT was 1.49 ± 0.14 mA. In unanesthetized rats, the average current required to generate ECAPs was 0.09 ± 0.02 mA, while the average current required to observe MT was 0.27 ± 0.04 mA. Thus, there was a significant difference between the ECAPT and MT in both anesthetized and unanesthetized rats (MT was 13.39 ± 2.40 and 2.84 ± 0.33 times higher than ECAPT, respectively). Signal analysis revealed average conduction velocities (CVs) suggesting that predominantly large, myelinated fibers were activated. In addition, a morphometric evaluation of spinal cord slices indicated that the custom-made lead may preferentially activate DC axons. CONCLUSIONS This is the first evidence demonstrating the feasibility of recording ECAPs from the rat spinal cord, which may be more useful in determining parameters of SCS in preclinical SCS models than MTs. Thus, this approach may allow for the development of a novel model of SCS in rats with chronic pain that will translate better between animals and humans.
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Affiliation(s)
| | - Dave Mugan
- Saluda Medical Europe Ltd, Harrogate, UK
| | - Quoc Chi Vuong
- Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, UK
| | - Ilona Obara
- School of Pharmacy, Newcastle University, Newcastle-upon-Tyne, UK.,Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, UK
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