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Mugan D, Vuong QC, Dietz BE, Obara I. Characterization of preclinical models to investigate spinal cord stimulation for neuropathic pain: a systematic review and meta-analysis. Pain Rep 2025; 10:e1228. [PMID: 39816902 PMCID: PMC11732658 DOI: 10.1097/pr9.0000000000001228] [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] [Received: 09/11/2024] [Revised: 10/23/2024] [Accepted: 10/30/2024] [Indexed: 01/18/2025] Open
Abstract
Despite advancements in preclinical and clinical spinal cord stimulation (SCS) research, the mechanisms of SCS action remain unclear. This may result from challenges in translatability of findings between species. Our systematic review (PROSPERO: CRD42023457443) aimed to comprehensively characterize the important translational components of preclinical SCS models, including stimulating elements and stimulation specifications. Databases (Embase, PubMed, Web of Science, and WikiStim) were searched on October 5, 2023, identifying 78 studies meeting the search criteria. We conducted a post hoc meta-analysis, including subgroup analyses and meta-regression, to assess SCS efficacy on mechanical hypersensitivity in rats subjected to neuropathic pain. Although monopolar electrodes were predominantly used as stimulating elements until 2013, quadripolar paddle and cylindrical leads gained recent popularity. Most research was conducted using 50 Hz and 200 µs stimulation. Motor threshold (MT) estimation was the predominant strategy to determine SCS intensity, which was set to 71.9% of MT on average. Our analysis revealed a large effect size for SCS (Hedge g = 1.13, 95% CI: [0.93, 1.32]) with similar magnitudes of effect between conventional (≤100 Hz) and nonconventional SCS paradigms while sham SCS had nonsignificant effect size. In addition, different stimulation intensity, frequency, and electrode design did not affect effect size. The risk of bias was assessed using Systematic Review Centre for Laboratory animal Experimentation criteria and was unclear, and only the frequency subgroup analysis showed publication bias. In summary, our review characterizes the critical components of preclinical SCS models and provides recommendations to improve reproducibility and translatability, thereby advancing the scientific foundation for SCS research.
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Affiliation(s)
- Dave Mugan
- School of Pharmacy, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Saluda Medical Europe Ltd, Harrogate, United Kingdom
| | - Quoc C. Vuong
- Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- School of Psychology, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Birte E. Dietz
- School of Pharmacy, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Saluda Medical Europe Ltd, Harrogate, United Kingdom
| | - Ilona Obara
- School of Pharmacy, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
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Xu Q, Zheng Q, Cui X, Cleland A, Hincapie J, Raja SN, Dong X, Guan Y. Visualizing the modulation of neurokinin 1 receptor-positive neurons in the superficial dorsal horn by spinal cord stimulation in vivo. Pain 2025; 166:428-437. [PMID: 39140483 PMCID: PMC11723817 DOI: 10.1097/j.pain.0000000000003361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/25/2024] [Indexed: 08/15/2024]
Abstract
ABSTRACT Spinal cord stimulation (SCS) is an effective modality for pain treatment, yet its underlying mechanisms remain elusive. Neurokinin 1 receptor-positive (NK1R + ) neurons in spinal lamina I play a pivotal role in pain transmission. To enhance our mechanistic understanding of SCS-induced analgesia, we investigated how different SCS paradigms modulate the activation of NK1R + neurons, by developing NK1R-Cre;GCaMP6s transgenic mice and using in vivo calcium imaging of superficial NK1R + neurons under anesthesia (1.5% isoflurane). Neurokinin 1 receptor-positive neurons in the lumbar spinal cord (L4-5) showed a greater activation by electrical test stimulation (TS, 3.0 mA, 1 Hz) at the hindpaw at 2 weeks after tibia-sparing nerve injury (SNI-t) than in naïve mice. Spinal cord stimulation was then delivered through a bipolar plate electrode placed epidurally at L1-2 level. The short-term 50-Hz high-intensity SCS (80% motor threshold [MoT], 10 minutes) induced robust and prolonged inhibition of NK1R + neuronal responses to TS in both naïve and SNI-t mice. The 30-minute 50-Hz and 900-Hz SCS applied at moderate intensity (50% MoT) also significantly inhibited neuronal responses in SNI-t mice. However, at low intensity (20% MoT), the 30-minute 900-Hz SCS only induced persistent neuronal inhibition in naïve mice, but not in SNI-t mice. In conclusion, both 10-minute high-intensity SCS and 30-minute SCS at moderate intensity inhibit the activation of superficial NK1R + neurons, potentially attenuating spinal nociceptive transmission. Furthermore, in vivo calcium imaging of NK1R + neurons provides a new approach for exploring the spinal neuronal mechanisms of pain inhibition by neuromodulation pain therapies.
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Affiliation(s)
- Qian Xu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qin Zheng
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Xiang Cui
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | | | | | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurological Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurological Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA
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Wu N, Wu Z, Zhang C, Wu C, Huo X, Bai J, Zhang G. Retrograde evoked compound action potentials as an alternative for close-loop spinal cord stimulation. Sci Rep 2024; 14:30141. [PMID: 39627483 PMCID: PMC11615308 DOI: 10.1038/s41598-024-81775-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Accepted: 11/28/2024] [Indexed: 12/06/2024] Open
Abstract
Evoked compound action potential (ECAP) is an important parameter in close-loop spinal cord stimulation (SCS). The recording electrode is typically positioned proximal to the stimulation electrode to capture the antegrade ECAP signals generated by ascending fibers. However, relatively little research has been conducted on retrograde ECAPs. This study investigated retrograde ECAPs using custom-made epidural electrodes in 11 adult male Sprague-Dawley rats. Results show that the average motor threshold (MT) and ECAP threshold (ECAPT) for 11 anesthetized rats were 218.18 ± 69.54 μA and 107.27 ± 27.96 μA, respectively. The ECAP amplitudes increased with increasement of the stimulation current and pulse width (PW), and were larger in awake rats than in anesthetized rats. Additionally, aside from ECAPs recorded by a commercial electrophysiological recorder, ECAPs were also recorded by a custom-made amplifier for the purpose of future long-term implantation, but the custom-made amplifier showed lower signal to noise ratio than the commercial amplifier. In conclusion, this study illustrates that retrograde ECAP may also be considered as a feedback signal for close-loop SCS and more sophisticated ECAP recording circuits are needed to form a close-loop system.
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Affiliation(s)
- Nianshuang Wu
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhen Wu
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Cheng Zhang
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Changzhe Wu
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiaolin Huo
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jinzhu Bai
- Department of Spine and Spinal Cord Surgery, Beijing Bo'ai Hospital, Rehabilitation Research Center, Beijing, China
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
| | - Guanghao Zhang
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
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Wang D, Yeop Lee K, Lee D, Kagan ZB, Bradley K. 10 kHz spinal cord stimulation improves metrics of spinal sensory processing in a male STZ rat model of diabetes. Neurosci Lett 2024; 842:137990. [PMID: 39278460 DOI: 10.1016/j.neulet.2024.137990] [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: 05/22/2024] [Revised: 09/11/2024] [Accepted: 09/12/2024] [Indexed: 09/18/2024]
Abstract
To explore why clinical 10 kHz spinal cord stimulation (10 kHz SCS) might improve neurological function in a model of painful diabetic neuropathy (PDN), the short-term behavioral, electrophysiological, and histological effects of 10 kHz SCS were studied using adult male streptozotocin (STZ)-induced diabetic Sprague-Dawley rats. Four testing groups were established: Naïve controls (N = 8), STZ controls (N = 7), STZ+Sham SCS (N = 9), and STZ+10 kHz SCS (N = 11). After intraperitoneal injection (60 mg/kg) of STZ caused the rats to become hyperglycemic, SCS electrodes were implanted in the dorsal epidural space over the L5-L6 spinal segments in the STZ+Sham SCS and STZ+10 kHz SCS groups and were stimulated for 14 days. The von Frey filament paw withdrawal threshold was measured weekly. At termination, animals were anesthetized and the electrophysiologic response of dorsal horn neurons (receptive field size, vibration, radiant warmth) of the ipsilateral foot was measured. Tissue from the plantar paw surface was obtained post-euthanization for intraepidermal nerve fiber density measurements. In comparison to other control groups, while no significant effect of 10 kHz SCS on peripheral intraepidermal nerve fiber density was observed, 10 kHz SCS 'normalized' the central neural response to vibration, receptive field, and paw withdrawal threshold, and elevated the neural response to tissue recovery from warm stimuli. These results suggest that short-term, low intensity 10 kHz SCS operates in the spinal cord to ameliorate compromised sensory processing, and may compensate for reduced peripheral sensory functionality from chronic hyperglycemia, thereby treating a broader spectrum of the sensory symptoms in diabetic neuropathy.
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Affiliation(s)
- Dong Wang
- Nevro Corp, 1800 Bridge Pkwy, Redwood City, CA 94065, USA.
| | - Kwan Yeop Lee
- Nevro Corp, 1800 Bridge Pkwy, Redwood City, CA 94065, USA.
| | - Dongchul Lee
- Nevro Corp, 1800 Bridge Pkwy, Redwood City, CA 94065, USA.
| | | | - Kerry Bradley
- Nevro Corp, 1800 Bridge Pkwy, Redwood City, CA 94065, USA.
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Nijhuis H, Kallewaard JW, van de Minkelis J, Hofsté WJ, Elzinga L, Armstrong P, Gültuna I, Almac E, Baranidharan G, Nikolic S, Gulve A, Vesper J, Dietz BE, Mugan D, Huygen FJPM. Durability of Evoked Compound Action Potential (ECAP)-Controlled, Closed-Loop Spinal Cord Stimulation (SCS) in a Real-World European Chronic Pain Population. Pain Ther 2024; 13:1119-1136. [PMID: 38954217 PMCID: PMC11393244 DOI: 10.1007/s40122-024-00628-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024] Open
Abstract
INTRODUCTION Closed-loop spinal cord stimulation (CL-SCS) is a recently introduced system that records evoked compound action potentials (ECAPs) from the spinal cord elicited by each stimulation pulse and uses this information to automatically adjust the stimulation strength in real time, known as ECAP-controlled SCS. This innovative system compensates for fluctuations in the distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a predetermined target level. This data collection study was designed to assess the performance of the first CL-SCS system in a real-world setting under normal conditions of use in multiple European centers. The study analyzes and presents clinical outcomes and electrophysiological and device data and compares these findings with those reported in earlier pre-market studies of the same system. METHODS This prospective, multicenter, observational study was conducted in 13 European centers and aimed to gather electrophysiological and device data. The study focused on the real-world application of this system in treating chronic pain affecting the trunk and/or limbs, adhering to standard conditions of use. In addition to collecting and analyzing basic demographic information, the study presents data from the inaugural patient cohort permanently implanted at multiple European centers. RESULTS A significant decrease in pain intensity was observed for overall back or leg pain scores (verbal numerical rating score [VNRS]) between baseline (mean ± standard error of the mean [SEM]; n = 135; 8.2 ± 0.1), 3 months (n = 93; 2.3 ± 0.2), 6 months (n = 82; 2.5 ± 0.3), and 12 months (n = 76; 2.5 ± 0.3). Comparison of overall pain relief (%) to the AVALON and EVOKE studies showed no significant differences at 3 and 12 months between the real-world data release (RWE; 71.3%; 69.6%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies. Further investigation was undertaken to objectively characterize the physiological parameters of SCS therapy in this cohort using the metrics of percent time above ECAP threshold (%), dose ratio, and dose accuracy (µV), according to previously described methods. Results showed that a median of 90% (40.7-99.2) of stimuli were above the ECAP threshold, with a dose ratio of 1.3 (1.1-1.4) and dose accuracy of 4.4 µV (0.0-7.1), based on data from 236, 230, and 254 patients, respectively. Thus, across all three metrics, the majority of patients had objective therapy metrics corresponding to the highest levels of pain relief in previously reported studies (usage over threshold > 80%, dose ratio > 1.2, and error < 10 µV). CONCLUSIONS In conclusion, this study provides valuable insights into the real-world application of the ECAP-controlled CL-SCS system, highlighting its potential for maintaining effective pain relief and objective neurophysiological therapy metrics at levels seen in randomized control trials, and potential for quantifying patient burden associated with SCS system use via patient-device interaction metrics. CLINICAL TRIAL REGISTRATION In the Netherlands, the study is duly registered on the International Clinical Trials Registry Platform (Trial NL7889). In Germany, the study is duly registered as NCT05272137 and in the United Kingdom as ISCRTN27710516 and has been reviewed by the ethics committee in both countries.
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Affiliation(s)
- Harold Nijhuis
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM, Nieuwegein, Netherlands.
| | - Jan-Willem Kallewaard
- Rijnstate Hospital, Velp, Netherlands
- Erasmus University Medical Center, Rotterdam, Netherlands
| | | | - Willem-Jan Hofsté
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM, Nieuwegein, Netherlands
| | | | | | | | - Emre Almac
- Alrijne Hospital, Leiderdorp, Netherlands
| | | | | | - Ashish Gulve
- James Cook University Hospital, Middlesbrough, UK
| | - Jan Vesper
- Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | | | - Dave Mugan
- Saluda Medical Europe Ltd, Harrogate, UK
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Kitamura I, Frazure M, Iceman K, Koike T, Pitts T. Stochastic electrical stimulation of the thoracic or cervical regions with surface electrodes facilitates swallow in rats. Front Neurol 2024; 15:1390524. [PMID: 39045426 PMCID: PMC11263167 DOI: 10.3389/fneur.2024.1390524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 06/20/2024] [Indexed: 07/25/2024] Open
Abstract
Introduction Aspiration pneumonia, a leading cause of mortality, poses an urgent challenge in contemporary society. Neuromuscular electrical stimulation (NMES) has been commonly used in dysphagia rehabilitation. However, given that NMES at motor threshold targets only specific muscles, it carries a potential risk of further compromising functions related to swallowing, respiration, and airway protection. Considering that the swallow motor pattern is orchestrated by the entire swallow pattern generator (the neural mechanism governing a sequence of swallow actions), a rehabilitation approach that centrally facilitates the entire circuit through sensory nerve stimulation is desirable. In this context, we propose a novel stimulation method using surface electrodes placed on the back to promote swallowing. Methods The efficacy of the proposed method in promoting swallowing was evaluated by electrically stimulating sensory nerves in the back or neck. Probabilistic stimulus was applied to either the back or neck of male and female rats. Swallows were evoked by an oral water stimulus, and electromyographic (EMG) activity of the mylohyoid, thyroarytenoid, and thyropharyngeus muscles served as the primary outcome measure. Results Gaussian frequency stimulation applied to the skin surface of the thoracic back elicited significant increases in EMG amplitude of all three swallow-related muscles. Neck stimulation elicited a significant increase in EMG amplitude of the thyroarytenoid during swallow, but not the mylohyoid or thyropharyngeus muscles. Discussion While the targeted thoracic spinal segments T9-T10 have been investigated for enhancing respiration, the promotion of swallowing through back stimulation has not been previously studied. Furthermore, this study introduces a new probabilistic stimulus based on Gaussian distribution. Probabilistic stimuli have been reported to excel in nerve stimulation in previous research. The results demonstrate that back stimulation effectively facilitated swallow more than neck stimulation and suggest potential applications for swallowing rehabilitation.
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Affiliation(s)
- In Kitamura
- Department of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Chōfu, Tokyo, Japan
| | - Michael Frazure
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY, United States
| | - Kimberly Iceman
- Department of Speech, Language, and Hearing Sciences and Dalton Cardiovascular Center, University of Missouri, Columbia, MO, United States
| | - Takuji Koike
- Department of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Chōfu, Tokyo, Japan
| | - Teresa Pitts
- Department of Speech, Language, and Hearing Sciences and Dalton Cardiovascular Center, University of Missouri, Columbia, MO, United States
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He Q, Yang C, Xu Y, Niu H, Wu H, Huang H, Chai X, Cao T, Wang N, Wong P, He J, Yang Y, Zhao J. Anatomical-related factors and outcome of percutaneous short-term spinal cord stimulation electrode shift in patients with disorders of consciousness: a retrospective study. Front Aging Neurosci 2024; 16:1403156. [PMID: 39015472 PMCID: PMC11249574 DOI: 10.3389/fnagi.2024.1403156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 06/17/2024] [Indexed: 07/18/2024] Open
Abstract
Background Disorders of consciousness (DoC) represent a spectrum of neurological conditions that pose significant treatment challenges. Percutaneous short-term spinal cord stimulation (SCS) has emerged as a promising experimental diagnostic treatment to assess and potentially improve consciousness levels. However, the effectiveness of this intervention is frequently compromised by the shift of electrodes, particularly in the cervical region, which can negatively affect therapeutic outcomes. Methods This retrospective study aimed to study if electrodes shift in percutaneous short-term SCS in patients with DoC would affect the outcome. We analyzed the relationship between electrode shift length and patient outcome, as well as the correlation with various anatomical parameters, including the actual length of the cervical spine, linear length, spinal canal transverse diameter, spinal canal diameter, and C2 cone height, in a cohort of patients undergoing the procedure. Results Our findings revealed that in patients with better outcome, there are significant less patient with electrode shift (p = 0.019). Further, a linear correlation was found between the length of electrode shift and patients' outcome (Rho = 0.583, p = 0.002), with longer shift lengths associated with poorer outcomes. Contrary to our expectations, there was no significant association between the measured anatomical parameters and the extent of electrode shift. However, a trend was found between the actual length of the cervical spine and the shift of the electrode (p = 0.098). Notably, the shorter spinal canal transverse diameter was found to be significantly associated with better outcome in patients with DoC receiving percutaneous short-term SCS (p = 0.033). Conclusion These results highlight the clinical importance of electrode stability in the cervical region during SCS treatment for patients with DoC. Ensuring secure placement of electrodes may play a crucial role in enhancing patients' outcome and minimize postoperative complications. Given the lack of association with expected anatomical parameters, future research should investigate other factors that could impact electrode stability to optimize this therapeutic intervention.
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Affiliation(s)
- Qiheng He
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Chaozhi Yang
- Department of Neurosurgery, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Yangxi Xu
- Department of Neurosurgery, The People’s Hospital of Liaoning Province, Shengyang, China
| | - Hongchuan Niu
- Department of Neurosurgery, Peking University International Hospital, Beijing, China
| | - Haitao Wu
- Department of Neurosurgery, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Haitao Huang
- Department of Neurosurgery, The People’s Hospital of Liaoning Province, Shengyang, China
| | - Xiaoke Chai
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Center for Neurological Disorders, Beijing, China
| | - Tianqing Cao
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Nan Wang
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Peiling Wong
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Jianghong He
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yi Yang
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Center for Neurological Disorders, Beijing, China
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- Chinese Institute for Brain Research, Beijing, China
- Beijing Institute of Brain Disorders, Beijing, China
| | - Jizong Zhao
- China National Center for Neurological Disorders, Beijing, China
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
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Wang D, Lee KY, Kagan ZB, Bradley K, Lee D. Frequency-Dependent Neural Modulation of Dorsal Horn Neurons by Kilohertz Spinal Cord Stimulation in Rats. Biomedicines 2024; 12:1346. [PMID: 38927553 PMCID: PMC11201430 DOI: 10.3390/biomedicines12061346] [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: 04/26/2024] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Kilohertz high-frequency spinal cord stimulation (kHF-SCS) is a rapidly advancing neuromodulatory technique in the clinical management of chronic pain. However, the precise cellular mechanisms underlying kHF-SCS-induced paresthesia-free pain relief, as well as the neural responses within spinal pain circuits, remain largely unexplored. In this study, using a novel preparation, we investigated the impact of varying kilohertz frequency SCS on dorsal horn neuron activation. Employing calcium imaging on isolated spinal cord slices, we found that extracellular electric fields at kilohertz frequencies (1, 3, 5, 8, and 10 kHz) induce distinct patterns of activation in dorsal horn neurons. Notably, as the frequency of extracellular electric fields increased, there was a clear and significant monotonic escalation in neuronal activity. This phenomenon was observed not only in superficial dorsal horn neurons, but also in those located deeper within the dorsal horn. Our study demonstrates the unique patterns of dorsal horn neuron activation in response to varying kilohertz frequencies of extracellular electric fields, and we contribute to a deeper understanding of how kHF-SCS induces paresthesia-free pain relief. Furthermore, our study highlights the potential for kHF-SCS to modulate sensory information processing within spinal pain circuits. These insights pave the way for future research aimed at optimizing kHF-SCS parameters and refining its therapeutic applications in the clinical management of chronic pain.
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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: 8] [Impact Index Per Article: 8.0] [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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Wahezi SE, Caparo MA, Malhotra R, Sundaram L, Batti K, Ejindu P, Veeramachaneni R, Anitescu M, Hunter CW, Naeimi T, Farah F, Kohan L. Current Waveforms in Spinal Cord Stimulation and Their Impact on the Future of Neuromodulation: A Scoping Review. Neuromodulation 2024; 27:47-58. [PMID: 38184341 DOI: 10.1016/j.neurom.2023.11.002] [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: 09/10/2023] [Revised: 10/16/2023] [Accepted: 11/13/2023] [Indexed: 01/08/2024]
Abstract
BACKGROUND Neuromodulation is a standard and well-accepted treatment for chronic refractory neuropathic pain. There has been progressive innovation in the field over the last decade, particularly in areas of spinal cord stimulation (SCS) and dorsal root ganglion stimulation. Improved outcomes using proprietary waveforms have become customary in the field, leading to an unprecedented expansion of these products and a plethora of options for the management of pain. Although advances in waveform technology have improved our fundamental understanding of neuromodulation, a scoping review describing new energy platforms and their associated clinical effects and outcomes is needed. The authors submit that understanding electrophysiological neuromodulation may be important for clinical decision-making and programming selection for personalized patient care. OBJECTIVE This review aims to characterize ways differences in mechanism of action and clinical outcomes of current spinal neuromodulation products may affect contemporary clinical decision-making while outlining a possible path for the future SCS. STUDY DESIGN The study is a scoping review of the literature about newer generation SCS waveforms. MATERIALS AND METHODS A literature report was performed on PubMed and chapters to include articles on spine neuromodulation mechanism of action and efficacy. RESULTS A total of 8469 studies were identified, 75 of which were included for the scoping review after keywords defining recent waveform technology were added. CONCLUSIONS Clinical data suggest that neuromodulation remains a promising tool in the treatment of chronic pain. The evidence for SCS for treating chronic pain seems compelling; however, more long-term and comparative data are needed for a comparison of waveforms when it comes to the etiology of pain. In addition, an exploration into combination waveform therapy and waveform cycling may be paramount for future clinical studies and the development of new technologies.
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Affiliation(s)
- Sayed E Wahezi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA.
| | - Moorice A Caparo
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Ria Malhotra
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lakshman Sundaram
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Kevin Batti
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Prince Ejindu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | | | - Magdalena Anitescu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Corey W Hunter
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Tahereh Naeimi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Fadi Farah
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lynn Kohan
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
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11
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Taccola G, Kissane R, Culaclii S, Apicella R, Liu W, Gad P, Ichiyama RM, Chakrabarty S, Edgerton VR. Dynamic electrical stimulation enhances the recruitment of spinal interneurons by corticospinal input. Exp Neurol 2024; 371:114589. [PMID: 37907125 DOI: 10.1016/j.expneurol.2023.114589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/12/2023] [Accepted: 10/25/2023] [Indexed: 11/02/2023]
Abstract
Highly varying patterns of electrostimulation (Dynamic Stimulation, DS) delivered to the dorsal cord through an epidural array with 18 independent electrodes transiently facilitate corticospinal motor responses, even after spinal injury. To partly unravel how corticospinal input are affected by DS, we introduced a corticospinal platform that allows selective cortical stimulation during the multisite acquisition of cord dorsum potentials (CDPs) and the simultaneous supply of DS. Firstly, the epidural interface was validated by the acquisition of the classical multisite distribution of CDPs and their input-output profile elicited by pulses delivered to peripheral nerves. Apart from increased EMGs, DS selectively increased excitability of the spinal interneurons that first process corticospinal input, without changing the magnitude of commands descending from the motor cortex, suggesting a novel correlation between muscle recruitment and components of cortically-evoked CDPs. Finally, DS increases excitability of post-synaptic spinal interneurons at the stimulation site and their responsiveness to any residual supraspinal control, thus supporting the use of electrical neuromodulation whenever the motor output is jeopardized by a weak volitional input, due to a partial disconnection from supraspinal structures and/or neuronal brain dysfunctions.
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Affiliation(s)
- Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Roger Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Department of Musculoskeletal & Ageing Science, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA; UCLA California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Parag Gad
- SpineX Inc, Los Angeles, CA 90064, USA
| | - Ronaldo M Ichiyama
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Samit Chakrabarty
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - V Reggie Edgerton
- Rancho Research Institute, Los Amigos National Rehabilitation Center, Downey, CA 90242, USA; University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, Badalona 08916, Spain
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12
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Gmel GE, Santos Escapa R, Benkohen TE, Mugan D, Parker JL, Palmisani S. Postsynaptic dorsal column pathway activation during spinal cord stimulation in patients with chronic pain. Front Neurosci 2023; 17:1297814. [PMID: 38188030 PMCID: PMC10771283 DOI: 10.3389/fnins.2023.1297814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/08/2023] [Indexed: 01/09/2024] Open
Abstract
Spinal cord stimulation (SCS) treatment for chronic pain relies on the activation of primary sensory fibres ascending to the brain in the dorsal columns. While the efficacy of SCS has been demonstrated, the precise mechanism of action and nature of the fibres activated by stimulation remain largely unexplored. Our investigation in humans with chronic neuropathic pain undergoing SCS therapy, found that post-synaptic dorsal column (PSDC) fibres can be activated synaptically by the primary afferents recruited by stimulation, and axonically by the stimulation pulses directly. Synaptic activation occurred in 9 of the 14 patients analysed and depended on the vertebral level of stimulation. A clear difference in conduction velocities between the primary afferents and the PSDC fibres were observed. Identification of PSDC fibre activation in humans emphasises the need for further investigation into the role they play in pain relief and the sensory response sensation (paraesthesia) experienced by patients undergoing SCS.
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Affiliation(s)
| | | | | | - Dave Mugan
- Saluda Medical, Macquarie Park, NSW, Australia
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13
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Taccola G, Kissane R, Culaclii S, Apicella R, Liu W, Gad P, Ichiyama RM, Chakrabarty S, Edgerton VR. Spinal facilitation of descending motor input. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.30.547229. [PMID: 37461548 PMCID: PMC10349979 DOI: 10.1101/2023.06.30.547229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Highly varying patterns of electrostimulation (Dynamic Stimulation, DS) delivered to the dorsal cord through an epidural array with 18 independent electrodes transiently facilitate corticospinal motor responses, even after spinal injury. To partly unravel how corticospinal input are affected by DS, we introduced a corticospinal platform that allows selective cortical stimulation during the multisite acquisition of cord dorsum potentials (CDPs) and the simultaneous supply of DS. Firstly, the epidural interface was validated by the acquisition of the classical multisite distribution of CDPs on the dorsal cord and their input-output profile elicited by pulses delivered to peripheral nerves. Apart from increased EMGs, DS selectively increased excitability of the spinal interneurons that first process corticospinal input, without changing the magnitude of commands descending from the motor cortex, suggesting a novel correlation between muscle recruitment and components of cortically-evoked CDPs. Finally, DS increases excitability of post-synaptic spinal interneurons at the stimulation site and their responsiveness to any residual supraspinal control, thus supporting the use of electrical neuromodulation whenever the motor output is jeopardized by a weak volitional input, due to a partial disconnection from supraspinal structures and/or neuronal brain dysfunctions.
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Affiliation(s)
- Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Roger Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Department of Musculoskeletal & Ageing Science, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
- UCLA California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Parag Gad
- Rancho Research Institute, Downy, CA 90242, USA; Los Amigos National Rehabilitation Center
- University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA
| | - Ronaldo M. Ichiyama
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Samit Chakrabarty
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - V. Reggie Edgerton
- Rancho Research Institute, Downy, CA 90242, USA; Los Amigos National Rehabilitation Center
- University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA
- Institut Guttmann. Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain
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14
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Calvert JS, Darie R, Parker SR, Shaaya E, Syed S, McLaughlin BL, Fridley JS, Borton DA. Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation. Neuromodulation 2023; 26:961-974. [PMID: 35551869 PMCID: PMC9643656 DOI: 10.1016/j.neurom.2022.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/07/2022] [Accepted: 03/23/2022] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Recent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation. MATERIALS AND METHODS In each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles. RESULTS We observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array. CONCLUSIONS These results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.
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Affiliation(s)
- Jonathan S Calvert
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Radu Darie
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Samuel R Parker
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Elias Shaaya
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | - Sohail Syed
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | | | - Jared S Fridley
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | - David A Borton
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA; Department of Veterans Affairs, Center for Neurorestoration and Neurotechnology, Providence, RI, USA; Carney Institute for Brain Science, Brown University, Providence, RI, USA.
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15
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Sharma M, Bhaskar V, Yang L, FallahRad M, Gebodh N, Zhang T, Esteller R, Martin J, Bikson M. Novel Evoked Synaptic Activity Potentials (ESAPs) Elicited by Spinal Cord Stimulation. eNeuro 2023; 10:ENEURO.0429-22.2023. [PMID: 37130780 PMCID: PMC10198607 DOI: 10.1523/eneuro.0429-22.2023] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/05/2023] [Accepted: 04/11/2023] [Indexed: 05/04/2023] Open
Abstract
Spinal cord stimulation (SCS) evokes fast epidural evoked compound action potential (ECAP) that represent activity of dorsal column axons, but not necessarily a spinal circuit response. Using a multimodal approach, we identified and characterized a delayed and slower potential evoked by SCS that reflects synaptic activity within the spinal cord. Anesthetized female Sprague Dawley rats were implanted with an epidural SCS lead, epidural motor cortex stimulation electrodes, an epidural spinal cord recording lead, an intraspinal penetrating recording electrode array, and intramuscular electromyography (EMG) electrodes in the hindlimb and trunk. We stimulated the motor cortex or the epidural spinal cord and recorded epidural, intraspinal, and EMG responses. SCS pulses produced characteristic propagating ECAPs (composed of P1, N1, and P2 waves with latencies <2 ms) and an additional wave ("S1") starting after the N2. We verified the S1-wave was not a stimulation artifact and was not a reflection of hindlimb/trunk EMG. The S1-wave has a distinct stimulation-intensity dose response and spatial profile compared with ECAPs. 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX; a selective competitive antagonist of AMPA receptors (AMPARs)] significantly diminished the S1-wave, but not ECAPs. Furthermore, cortical stimulation, which did not evoke ECAPs, produced epidurally detectable and CNQX-sensitive responses at the same spinal sites, confirming epidural recording of an evoked synaptic response. Finally, applying 50-Hz SCS resulted in dampening of S1-wave but not ECAPs. Therefore, we hypothesize that the S1-wave is synaptic in origin, and we term the S1-wave type responses: evoked synaptic activity potentials (ESAPs). The identification and characterization of epidurally recorded ESAPs from the dorsal horn may elucidate SCS mechanisms.
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Affiliation(s)
- Mahima Sharma
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Vividha Bhaskar
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Lillian Yang
- Department of Molecular, Cellular and Biomedical Sciences, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Mohamad FallahRad
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Nigel Gebodh
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Tianhe Zhang
- Boston Scientific Neuromodulation Research and Advanced Concepts, Valencia, CA 91355
| | - Rosana Esteller
- Boston Scientific Neuromodulation Research and Advanced Concepts, Valencia, CA 91355
| | - John Martin
- Department of Molecular, Cellular and Biomedical Sciences, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Marom Bikson
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
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16
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Kuo SW, Zhang T, Esteller R, Grill WM. In Vivo Measurements reveal that both low- and high-frequency spinal cord stimulation heterogeneously modulate superficial dorsal horn neurons. Neuroscience 2023; 520:119-131. [PMID: 37085007 DOI: 10.1016/j.neuroscience.2023.04.010] [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: 07/20/2022] [Revised: 03/01/2023] [Accepted: 04/08/2023] [Indexed: 04/23/2023]
Abstract
Current sub-perception spinal cord stimulation (SCS) is characterized by the use of high-frequency pulses to achieve paresthesia-free analgesic effects. High-frequency SCS demonstrates distinctive properties from paresthesia-based SCS, such as a longer time course to response, implying the existence of alternative mechanism(s) of action beyond gate control theory. We quantified the responses to SCS of single neurons within the superficial dorsal horn (SDH), a structure in close proximity to SCS electrodes, to investigate the mechanisms underlying high-frequency SCS in 62 urethane-anesthetized male rats. Sciatic nerve stimulation was delivered to isolate lumbar SDH neurons with evoked C-fiber activity. The evoked C-fiber activity before and after the application of SCS was compared to quantify the effects of SCS across stimulation intensity and stimulation duration at three different stimulation frequencies. We observed heterogeneous responses of SDH neurons which depended primarily on the type of unit. Low-threshold units with spontaneous activity, putatively inhibitory interneurons, tended to be facilitated by SCS while the other unit types were suppressed. The effects of SCS were more prominent with increased stimulation duration from 30 s to 30 m across frequencies. Our results highlight the importance of inhibitory interneurons in modulating local circuits of the SDH and the importance of local circuit contributions to the analgesic mechanisms of SCS.
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Affiliation(s)
- Su-Wei Kuo
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Tianhe Zhang
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Rosana Esteller
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC; Departments of Electrical and Computer Engineering, Neurobiology, and Neurosurgery, Duke University, Durham, NC.
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Cedeño DL, Vallejo R, Kelley CA, Platt DC, Litvak LM, Straka M, Dinsmoor DA. Spinal Evoked Compound Action Potentials in Rats With Clinically Relevant Stimulation Modalities. Neuromodulation 2023; 26:68-77. [PMID: 35961888 DOI: 10.1016/j.neurom.2022.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Rats are commonly used for translational pain and spinal cord stimulation (SCS) research. Although many SCS parameters are configured identically between rats and humans, stimulation amplitudes in rats are often programmed relative to visual motor threshold (vMT). Alternatively, amplitudes may be programmed relative to evoked compound action potential (ECAP) thresholds (ECAPTs), a sensed measure of neural activation. The objective of this study was to characterize ECAPTs, evoked compound muscle action potential thresholds (ECMAPTs), and vMTs with clinically relevant SCS modalities. MATERIALS AND METHODS We implanted ten anesthetized rats with two quadripolar epidural SCS leads: one for stimulating in the lumbar spine, and another for sensing ECAPs in the thoracic spine. We then delivered two SCS paradigms to the rats. The first used 50-Hz SCS with 50-, 100-, 150-, and 200-μs pulse widths (PWs), whereas the second used a 50-Hz, 150-μs PW low-rate program (LRP) multiplexed to a 1200-Hz, 50-μs PW high-rate program (HRP). We increased SCS amplitudes up to the vMT in the first paradigm, and in the second, we increased HRP amplitudes up to the HRP ECAPT with a fixed amplitude (70% of the vMT) LRP. For each test case, we captured ECAPTs, ECMAPTs, and vMTs from each rat. RESULTS vMTs were 3.0 ± 0.7 times greater than ECAPTs, with vMTs marginally (3.0 ± 3.6%) greater than ECMAPTs (mean ± SD) across all PWs with the first paradigm. With the second paradigm, we noted a negligible increase (3.6 ± 6.2%) on the LRP ECAP as HRP amplitudes were increased. CONCLUSIONS Our results demonstrate reasonable levels of neural activation in anesthetized rats with SCS amplitudes appropriately programmed relative to vMT or ECMAPT when using clinically relevant SCS modalities. Furthermore, we demonstrate the feasibility of ECAP recording in rats with multiplexed HRP SCS.
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