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Harland B, Kow CY, Svirskis D. Spinal intradural electrodes: opportunities, challenges and translation to the clinic. Neural Regen Res 2024; 19:503-504. [PMID: 37721274 PMCID: PMC10581576 DOI: 10.4103/1673-5374.380895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/27/2023] [Accepted: 06/09/2023] [Indexed: 09/19/2023] Open
Affiliation(s)
- Bruce Harland
- School of Pharmacy, University of Auckland, Auckland, New Zealand
| | - Chien Yew Kow
- Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Darren Svirskis
- School of Pharmacy, University of Auckland, Auckland, New Zealand
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Woodroffe RW, Pearson AC, Pearlman AM, Howard MA, Nauta HJW, Nagel SJ, Hori YS, Machado AG, Almeida Frizon L, Helland L, Holland MT, Gillies GT, Wilson S. Spinal Cord Stimulation for Visceral Pain: Present Approaches and Future Strategies. PAIN MEDICINE 2020; 21:2298-2309. [PMID: 32719876 DOI: 10.1093/pm/pnaa108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION The introduction of successful neuromodulation strategies for managing chronic visceral pain lag behind what is now treatment of choice in refractory chronic back and extremity pain for many providers in the United States and Europe. Changes in public policy and monetary support to identify nonopioid treatments for chronic pain have sparked interest in alternative options. In this review, we discuss the scope of spinal cord stimulation (SCS) for visceral pain, its limitations, and the potential role for new intradural devices of the type that we are developing in our laboratories, which may be able to overcome existing challenges. METHODS A review of the available literature relevant to this topic was performed, with particular focus on the pertinent neuroanatomy and uses of spinal cord stimulation systems in the treatment of malignant and nonmalignant gastrointestinal, genitourinary, and chronic pelvic pain. RESULTS To date, there have been multiple off-label reports testing SCS for refractory gastrointestinal and genitourinary conditions. Though some findings have been favorable for these organs and systems, there is insufficient evidence to make this practice routine. The unique configuration and layout of the pelvic pain pathways may not be ideally treated using traditional SCS implantation techniques, and intradural stimulation may be a viable alternative. CONCLUSIONS Despite the prevalence of visceral pain, the application of neuromodulation therapies, a standard approach for other painful conditions, has received far too little attention, despite promising outcomes from uncontrolled trials. Detailed descriptions of visceral pain pathways may offer several clues that could be used to implement devices tailored to this unique anatomy.
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Affiliation(s)
- Royce W Woodroffe
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Amy C Pearson
- Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Amy M Pearlman
- Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Matthew A Howard
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Haring J W Nauta
- Department of Neurosurgery, University of Louisville, Louisville, Kentucky
| | - S J Nagel
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, Ohio, USA
| | - Y S Hori
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, Ohio, USA
| | - Andre G Machado
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, Ohio, USA
| | | | - Logan Helland
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Marshall T Holland
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - George T Gillies
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Saul Wilson
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa
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Nagel SJ, Hsieh J, Machado AG, Frizon LA, Howard MA, Gillies GT, Wilson S. Biomarker Optimization of Spinal Cord Stimulation Therapies. Neuromodulation 2020; 24:3-12. [PMID: 32881257 DOI: 10.1111/ner.13252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We are in the process of designing and testing an intradural stimulation device that will shorten the distance between the location of the electrode array and the targeted neural tissue, thus improving the efficacy of electrical current delivery. Identifying a biomarker that accurately reflects the response to this intervention is highly valued because of the potential to optimize interventional parameters or predict a response before it is clinically measurable. In this report, we summarize the findings pertaining to the study of biomarkers so that we and others will have an up-to-date reference that critically evaluates the current approaches and select one or several for testing during the development of our device. MATERIALS AND METHODS We have conducted a broad survey of the existing literature to catalogue the biomarkers that could be coupled to intradural spinal cord stimulation. We describe in detail some of the most promising biomarkers, existing limitations, and suitability to managing chronic pain. RESULTS Chronic, intractable pain is an all-encompassing condition that is incurable. Many treatments for managing chronic pain are nonspecific in action and intermittently administered; therefore, patients are particularly susceptible to large fluctuations in pain control over the course of a day. The absence of a reliable biomarker challenges assessment of therapeutic efficacy and contributes to either incomplete and inconsistent pain relief or, alternatively, intolerable side effects. Fluctuations in metabolites or inflammatory markers, signals captured during dynamic imaging, and genomics will likely have a role in governing how a device is modulated. CONCLUSIONS Efforts to identify one or more biomarkers are well underway with some preliminary evidence supporting their efficacy. This has far-reaching implications, including improved outcomes, fewer adverse events, harmonization of treatment and individuals, performance gains, and cost savings. We anticipate that novel biomarkers will be used widely to manage chronic pain.
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Affiliation(s)
- Sean J Nagel
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, OH, USA
| | - Jason Hsieh
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, OH, USA
| | - Andre G Machado
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, OH, USA
| | - Leonardo A Frizon
- Department of Neurosurgery, Hospital Marcelino Champagnat, Curitiba, PR, Brazil
| | - Matthew A Howard
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - George T Gillies
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA
| | - Saul Wilson
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
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Holland MT, Seaman SC, Woodroffe RW, Fredericks DC, Kovach CK, Gibson-Corley KN, Gillies GT, Howard MA. In Vivo Testing of a Prototype Intradural Spinal Cord Stimulator in a Porcine Model. World Neurosurg 2020; 137:e634-e641. [PMID: 32112934 DOI: 10.1016/j.wneu.2020.02.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Chronic midline low back pain is the number one reason for disability in the United States despite the prolific use of medical and surgical interventions. Notwithstanding the widespread use of epidural spinal cord stimulators (SCSs), there remains a large portion of the population with inadequate pain control thought to be because of the limited volume of stimulated neural tissue. Intradural SCSs represent an underexplored alternative strategy with the potential to improve selectivity, power efficiency, and efficacy. We studied and carried out development of an intradural form of an SCS. Herein we present the findings of in vivo testing of a prototype intradural SCS in a porcine model. METHODS Six female juvenile pigs underwent surgical investigation. One control animal underwent a laminectomy only, whereas the 5 other animals had implantation of an intradural SCS prototype. One of the prototypes was fully wired to enable acute stimulation and concurrent electromyographic recordings. All animals underwent terminal surgery 3 months postimplantation, with harvesting of the spinal column. Imaging (microcomputed tomography scan) and histopathologic examinations were subsequently performed. RESULTS All animals survived implantation without evidence of neurologic deficits or infection. Postmortem imaging and histopathologic examination of the spinal column revealed no evidence of spinal cord damage, cerebrospinal fluid fistula formation, abnormal bony overgrowth, or dural defect. Viable dura was present between the intra- and extradural plates of the device. Electromyographic recordings revealed evoked motor units from the stimulator. CONCLUSIONS Chronically implanted intradural device in the porcine model demonstrated safety and feasibility for translation into humans.
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Affiliation(s)
- Marshall T Holland
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Scott C Seaman
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Royce W Woodroffe
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Douglas C Fredericks
- Department of Orthopedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Christopher K Kovach
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | | | - George T Gillies
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Matthew A Howard
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
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Anderson DJ, Kipke DR, Nagel SJ, Lempka SF, Machado AG, Holland MT, Gillies GT, Howard MA, Wilson S. Intradural Spinal Cord Stimulation: Performance Modeling of a New Modality. Front Neurosci 2019; 13:253. [PMID: 30941012 PMCID: PMC6434968 DOI: 10.3389/fnins.2019.00253] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 03/04/2019] [Indexed: 12/23/2022] Open
Abstract
Introduction: Intradural spinal cord stimulation (SCS) may offer significant therapeutic benefits for those with intractable axial and extremity pain, visceral pain, spasticity, autonomic dysfunction and related disorders. A novel intradural electrical stimulation device, limited by the boundaries of the thecal sac, CSF and spinal cord was developed to test this hypothesis. In order to optimize device function, we have explored finite element modeling (FEM). Methods: COMSOL®Multiphysics Electrical Currents was used to solve for fields and currents over a geometric model of a spinal cord segment. Cathodic and anodic currents are applied to the center and tips of the T-cross component of the electrode array to shape the stimulation field and constrain charge-balanced cathodic pulses to the target area. Results: Currents from the electrode sites can move the effective stimulation zone horizontally across the cord by a linear step method, which can be diversified considerably to gain greater depth of penetration relative to standard epidural SCS. It is also possible to prevent spread of the target area with no off-target action potential. Conclusion: Finite element modeling of a T-shaped intradural spinal cord stimulator predicts significant gains in field depth and current shaping that are beyond the reach of epidural stimulators. Future studies with in vivo models will investigate how this approach should first be tested in humans.
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Affiliation(s)
- David J Anderson
- NeuroNexus Technologies, Ann Arbor, MI, United States.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Daryl R Kipke
- NeuroNexus Technologies, Ann Arbor, MI, United States
| | - Sean J Nagel
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, OH, United States
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Andre G Machado
- Center for Neurological Restoration, Cleveland Clinic, Cleveland, OH, United States
| | - Marshall T Holland
- Department of Neurosurgery, University of Iowa Hospitals & Clinics, Iowa City, IA, United States
| | - George T Gillies
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, United States
| | - Mathew A Howard
- Department of Neurosurgery, University of Iowa Hospitals & Clinics, Iowa City, IA, United States
| | - Saul Wilson
- Department of Neurosurgery, University of Iowa Hospitals & Clinics, Iowa City, IA, United States
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