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Revisiting intradural spinal cord stimulation: an introduction to a novel intradural spinal cord stimulation device

  • Brian D. Dalm

    Brian D. Dalm is a fifth-year neurosurgical resident at the University of Iowa Hospitals and Clinics. He received his Bsc degree in Physiology at Michigan State University in 2005. He then attended Loyola University Chicago Stritch School of Medicine, where he earned his MD in 2009. Dr. Dalm’s research interests focus on pain and neuromodulation. Currently, he is working with a rat model of neuropathic pain to assess for spontaneous pain and its correlation with spontaneous action potential firing in the dorsal horn.

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    , Sephanus V. Viljoen

    Sephanus V. Viljoen is a fifth-year neurosurgical resident at the University of Iowa Hospitals and Clinics. He received his BSc degree in Biochemistry at Nebraska Wesleyan University in 2005. He then attended the University of Nebraska Medical Center College of Medicine, where he earned his MD in 2009. Currently, Dr. Viljoen’s primary research focus is on assessing outcomes of surgical correction from patients with cervical myelopathy using a sophisticated gait analysis program.

    , Nader S. Dahdaleh

    Nader S. Dahdaleh first received his MD degree from the American University of Beirut prior to moving to the United States. After moving to the USA, he completed his residency in Neurosurgery at the University of Iowa in 2011. Afterward, Dr. Dahdaleh completed a surgical spine fellowship in minimally-invasive and complex spinal deformity at Northwestern University. Following his fellowship, he stayed on as a junior faculty member at Northwestern. While a resident, Dr. Dahdaleh published numerous clinical articles and also focused on research in the mouse amygdala. Currently, his research is focused on spine and spine-related pathology.

    , Chandan G. Reddy

    Chandan G. Reddy received his MD degree from the University of Michigan School of Medicine. Following medical school, he completed his neurosurgical residency training at the University of Iowa in 2010. He then completed a peripheral nerve fellowship with Dr. Spinner at the Mayo Clinic. Currently, he is a junior faculty member at the University of Iowa. His primary research interests are focused on pain and neuromodulation. Dr. Reddy is also working on refining a large animal model of neuropathic pain with the goal of studying spinal cord stimulation and its behavioral and electrophysiological effects.

    , Timothy J. Brennan

    Timothy J. Brennan is the Samir Gergis Professor of Anesthesia and Vice Chair for Research at the Department of Anesthesia at the University of Iowa. For the past 20 years, he has focused on pain mechanisms in preclinical pain models. The long-term goal of this research is to understand the etiology of pathological pain mechanism to facilitate analgesic drug development. Dr. Brennan is a member of the editorial boards of the Journal of Pain, Clinical Journal of Pain, and Pain. He has served on National Institutes of Health study sections and has published over 80 peer-reviewed publications and several chapters.

    , Hiroyuki Oya

    Hiroyuki Oya, MD, PhD, is an Associate Professor at the Department of Neurosurgery, University of Iowa. He received the board certification in Neurosurgery from Japan Neurosurgical Society in 1996. His practice in neurosurgery is based at both University of Iowa hospitals and clinics and Iowa City VA Medical Center. His research centers on the analysis of electrocorticography, functional and structural MRI in the human brain as well as the effect of electrical stimulation of the human brain and spinal cord. He is a member of Japan Neurosurgical Society and American Association of Neurological Surgeons.

    , Saul Wilson

    Saul Wilson received his MD degree from Louisiana State University prior to completing his neurosurgical residency training at the University of Iowa in 2009. Dr. Wilson then completed both an endovascular fellowship at the University of Memphis and a pediatric neurosurgery fellowship at Indiana University. Currently, Dr. Wilson is a junior faculty member at the University of Iowa. His research interest is focused on developing a large animal model of spasticity in the hopes of studying the therapeutic effects of spinal cord stimulation on spasticity.

    , Sina Safayi

    Sina Safayi is a post-doctoral research associate at the Department of Veterinary Clinical Sciences specialized in behavior/motion analysis at Iowa State University. He has a combination of advanced degrees in animal sciences – DVM, PhD, and European certificate for “Laboratory Animal Science” (category C) – with extensive experience in applied animal physiology including practical research ranging from molecular studies through live animal experiments (small/large ruminants, canine, swine, and rodents). He has currently more than 50 publications and presentations. He is currently developing new methods and successfully conducting different behavior analysis studies for diverse projects including various species (e.g., sheep, pigs, dogs). He is also collaborating with national as well as international research groups with designing their experiments, statistical analysis, histology, and image analysis.

    , Nicholas D. Jeffery

    Nicholas D. Jeffery is a UK-qualified veterinarian with specialist qualifications in clinical neurology and surgery. He has a PhD in Experimental Neurology, studying demyelination and remyelination of the nervous system. Currently, he is Professor of Neurology and Neurosurgery at the College of Veterinary Medicine, Iowa State University.

    , George T. Gilles

    George T. Gilles received his Bsc degree in Physics from North Dakota State University, Fargo, in 1974. He then received his MSc and PhD degrees in Engineering Physics in 1976 and 1980 from the University of Virginia, Charlottesville, where he is currently a Research Professor of Mechanical and Biomedical Engineering and a Visiting Research Professor of Physics at the School of Engineering and Applied Science. He was formerly with the International Bureau of Weights and Measures, Sevres, France, and at the US Department of Energy’s Oak Ridge Complex. His current research interests include medical device development, clinical magnetic manipulation systems, and precision measurement technology. He has authored or co-authored over 300 publications and holds 25 US Patents.

    und Matthew A. Howard

    Matthew A. Howard, MD, is Professor and Chairman of the Department of Neurological Surgery at the University of Iowa. Dr. Howard received his undergraduate degree in Physics from Tufts University. As a medical student at the University of Virginia, he collaborated with neurosurgery resident Dr. Sean Grady and Professor of Physics Rogers Ritter to invent the magnetic surgery system (MSS), whereby flexible implants within the body are guided by externally generated magnetic fields. Dr. Howard received his neurosurgery residency training at the University of Washington and Atkinson Morley’s Hospital in London, UK. During his residency, he was awarded an NIH Individual National Research Award to pursue 2 years of post-doctoral fellowship training in cortical electrophysiology research. In 1993, he joined the faculty at the University of Iowa and established the Human Brain Research Laboratory (HBRL) with collaborating neuroscience colleagues throughout the USA and overseas. Dr. Howard is an experienced medical device inventor with 27 issued US Patents, and he has co-founded four university spin-off medical device companies, including most recently Direct Spinal Therapeutics Inc. (DSTI). DSTI is developing a human spinal cord modulation system that will enable physicians to directly deliver electrical stimuli to neural targets within the human spinal cord. Dr. Howard has authored and co-authored 92 peer-reviewed publications. In 2014, Dr. Howard was selected by the Society of Neurological Surgery as the recipient of the Winn Prize, which is the specialty’s highest award for career achievement in neuroscience research.

Veröffentlicht/Copyright: 26. November 2014
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Abstract

Background: Spinal cord stimulation has been in use for decades and is growing as a therapeutic treatment option. A significant problem arising from the epidural location of the lead is electrical shunting through the cerebrospinal fluid, providing sub-optimal delivery of the electrical current specifically to the Aβ fibers of the dorsal column.

Objective: Our goal is to design a safe and effective intradural spinal cord stimulator (SCS) that places the stimulating electrodes directly against the pia similar to what is currently employed with the auditory brainstem implant.

Methods: We have reviewed the literature on the early original intradural SCSs and designed, built, and tested an improved device that seeks to overcome the limitations the existing epidural stimulators.

Results: In particular, we have shown that the present design of our device allows for motion of the spinal cord without the device being displaced itself, exerts a surface pressure on the spinal cord surface that is below what would cause ischemia or vessel injury, activates somato-sensory evoked potentials at a lower threshold than epidural stimulation, and (iv) does not cause deleterious neurological deficits in a chronic ovine model of intradural stimulator implantation.

Conclusion: While further studies to prove long-term safety and durability of the device are underway, we believe that revisiting an intradural approach to spinal cord stimulation may continue to improve our ability to treat certain chronic pain states and possibly the spasticity associated with spinal cord injuries.


Corresponding author: Brian D. Dalm, MD, Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA, Tel.: +1-319-356-8468, Fax: +1-319-353-6605, E-mail:

About the authors

Brian D. Dalm

Brian D. Dalm is a fifth-year neurosurgical resident at the University of Iowa Hospitals and Clinics. He received his Bsc degree in Physiology at Michigan State University in 2005. He then attended Loyola University Chicago Stritch School of Medicine, where he earned his MD in 2009. Dr. Dalm’s research interests focus on pain and neuromodulation. Currently, he is working with a rat model of neuropathic pain to assess for spontaneous pain and its correlation with spontaneous action potential firing in the dorsal horn.

Sephanus V. Viljoen

Sephanus V. Viljoen is a fifth-year neurosurgical resident at the University of Iowa Hospitals and Clinics. He received his BSc degree in Biochemistry at Nebraska Wesleyan University in 2005. He then attended the University of Nebraska Medical Center College of Medicine, where he earned his MD in 2009. Currently, Dr. Viljoen’s primary research focus is on assessing outcomes of surgical correction from patients with cervical myelopathy using a sophisticated gait analysis program.

Nader S. Dahdaleh

Nader S. Dahdaleh first received his MD degree from the American University of Beirut prior to moving to the United States. After moving to the USA, he completed his residency in Neurosurgery at the University of Iowa in 2011. Afterward, Dr. Dahdaleh completed a surgical spine fellowship in minimally-invasive and complex spinal deformity at Northwestern University. Following his fellowship, he stayed on as a junior faculty member at Northwestern. While a resident, Dr. Dahdaleh published numerous clinical articles and also focused on research in the mouse amygdala. Currently, his research is focused on spine and spine-related pathology.

Chandan G. Reddy

Chandan G. Reddy received his MD degree from the University of Michigan School of Medicine. Following medical school, he completed his neurosurgical residency training at the University of Iowa in 2010. He then completed a peripheral nerve fellowship with Dr. Spinner at the Mayo Clinic. Currently, he is a junior faculty member at the University of Iowa. His primary research interests are focused on pain and neuromodulation. Dr. Reddy is also working on refining a large animal model of neuropathic pain with the goal of studying spinal cord stimulation and its behavioral and electrophysiological effects.

Timothy J. Brennan

Timothy J. Brennan is the Samir Gergis Professor of Anesthesia and Vice Chair for Research at the Department of Anesthesia at the University of Iowa. For the past 20 years, he has focused on pain mechanisms in preclinical pain models. The long-term goal of this research is to understand the etiology of pathological pain mechanism to facilitate analgesic drug development. Dr. Brennan is a member of the editorial boards of the Journal of Pain, Clinical Journal of Pain, and Pain. He has served on National Institutes of Health study sections and has published over 80 peer-reviewed publications and several chapters.

Hiroyuki Oya

Hiroyuki Oya, MD, PhD, is an Associate Professor at the Department of Neurosurgery, University of Iowa. He received the board certification in Neurosurgery from Japan Neurosurgical Society in 1996. His practice in neurosurgery is based at both University of Iowa hospitals and clinics and Iowa City VA Medical Center. His research centers on the analysis of electrocorticography, functional and structural MRI in the human brain as well as the effect of electrical stimulation of the human brain and spinal cord. He is a member of Japan Neurosurgical Society and American Association of Neurological Surgeons.

Saul Wilson

Saul Wilson received his MD degree from Louisiana State University prior to completing his neurosurgical residency training at the University of Iowa in 2009. Dr. Wilson then completed both an endovascular fellowship at the University of Memphis and a pediatric neurosurgery fellowship at Indiana University. Currently, Dr. Wilson is a junior faculty member at the University of Iowa. His research interest is focused on developing a large animal model of spasticity in the hopes of studying the therapeutic effects of spinal cord stimulation on spasticity.

Sina Safayi

Sina Safayi is a post-doctoral research associate at the Department of Veterinary Clinical Sciences specialized in behavior/motion analysis at Iowa State University. He has a combination of advanced degrees in animal sciences – DVM, PhD, and European certificate for “Laboratory Animal Science” (category C) – with extensive experience in applied animal physiology including practical research ranging from molecular studies through live animal experiments (small/large ruminants, canine, swine, and rodents). He has currently more than 50 publications and presentations. He is currently developing new methods and successfully conducting different behavior analysis studies for diverse projects including various species (e.g., sheep, pigs, dogs). He is also collaborating with national as well as international research groups with designing their experiments, statistical analysis, histology, and image analysis.

Nicholas D. Jeffery

Nicholas D. Jeffery is a UK-qualified veterinarian with specialist qualifications in clinical neurology and surgery. He has a PhD in Experimental Neurology, studying demyelination and remyelination of the nervous system. Currently, he is Professor of Neurology and Neurosurgery at the College of Veterinary Medicine, Iowa State University.

George T. Gilles

George T. Gilles received his Bsc degree in Physics from North Dakota State University, Fargo, in 1974. He then received his MSc and PhD degrees in Engineering Physics in 1976 and 1980 from the University of Virginia, Charlottesville, where he is currently a Research Professor of Mechanical and Biomedical Engineering and a Visiting Research Professor of Physics at the School of Engineering and Applied Science. He was formerly with the International Bureau of Weights and Measures, Sevres, France, and at the US Department of Energy’s Oak Ridge Complex. His current research interests include medical device development, clinical magnetic manipulation systems, and precision measurement technology. He has authored or co-authored over 300 publications and holds 25 US Patents.

Matthew A. Howard

Matthew A. Howard, MD, is Professor and Chairman of the Department of Neurological Surgery at the University of Iowa. Dr. Howard received his undergraduate degree in Physics from Tufts University. As a medical student at the University of Virginia, he collaborated with neurosurgery resident Dr. Sean Grady and Professor of Physics Rogers Ritter to invent the magnetic surgery system (MSS), whereby flexible implants within the body are guided by externally generated magnetic fields. Dr. Howard received his neurosurgery residency training at the University of Washington and Atkinson Morley’s Hospital in London, UK. During his residency, he was awarded an NIH Individual National Research Award to pursue 2 years of post-doctoral fellowship training in cortical electrophysiology research. In 1993, he joined the faculty at the University of Iowa and established the Human Brain Research Laboratory (HBRL) with collaborating neuroscience colleagues throughout the USA and overseas. Dr. Howard is an experienced medical device inventor with 27 issued US Patents, and he has co-founded four university spin-off medical device companies, including most recently Direct Spinal Therapeutics Inc. (DSTI). DSTI is developing a human spinal cord modulation system that will enable physicians to directly deliver electrical stimuli to neural targets within the human spinal cord. Dr. Howard has authored and co-authored 92 peer-reviewed publications. In 2014, Dr. Howard was selected by the Society of Neurological Surgery as the recipient of the Winn Prize, which is the specialty’s highest award for career achievement in neuroscience research.

Acknowledgments

We would also like to thank R. Shurig, S. Scott, and R. S. Nelson at Evergreen Medical Technologies, Minneapolis, MN, USA, for their assistance with assembly of the I-Patch prototypes being used for experimental purposes.

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The authors stated that there are no conflicts of interest regarding the publication of this article.

Received: 2014-5-20
Accepted: 2014-9-29
Published Online: 2014-11-26
Published in Print: 2014-12-1

©2014 by De Gruyter

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