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Colella M, Cid LG, Liberti M, Apollonio F, Yu X, Ay I, Bonmassar G. Numerical Simulation and Experimental Studies of a Ribbon Coil for Trans Spinal Magnetic Stimulation (TSMS) in Rats . ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082681 DOI: 10.1109/embc40787.2023.10340213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
We propose a non-invasive Trans Spinal Magnetic Stimulation (TSMS) coil allowing for focal stimulation. The device is based on a new figure-8 ribbon design, ensuring low R0, and low heating. The two coils were designed and studied using the finite element method (FEM) coupled with NEURON and tested for efficacy on rats. The numerical simulations confirmed the generation of the observed action potentials when the coil was driven with 2.8kA.Clinical Relevance- Chronic neuropathic back and leg pain is one of the main indications for spinal cord stimulation in the United States. Chronic low back pain is one of the most common reasons patients seek medical care, and in 2013 resulted in 87.6 billion dollars in healthcare costs in the USA. Patients would most likely prefer a low-risk, non-invasive procedure, such as TSMS, to surgery with a significant rate of complications.
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Colella M, Press DZ, Laher RM, McIlduff CE, Rutkove SB, Cassarà AM, Apollonio F, Pascual-Leone A, Liberti M, Bonmassar G. A study of flex miniaturized coils for focal nerve magnetic stimulation. Med Phys 2023; 50:1779-1792. [PMID: 36502488 PMCID: PMC10033376 DOI: 10.1002/mp.16148] [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: 03/15/2022] [Revised: 09/01/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Peripheral magnetic stimulation (PMS) is emerging as a complement to standard electrical stimulation (ES) of the peripheral nervous system (PNS). PMS may stimulate sensory and motor nerve fibers without the discomfort associated with the ES used for standard nerve conduction studies. The PMS coils are the same ones used in transcranial magnetic stimulation (TMS) and lack focality and selectiveness in the stimulation. PURPOSE This study presents a novel coil for PMS, developed using Flexible technologies, and characterized by reduced dimensions for a precise and controlled targeting of peripheral nerves. METHODS We performed hybrid electromagnetic (EM) and electrophysiological simulations to study the EM exposure induced by a novel miniaturized coil (or mcoil) in and around the radial nerve of the neuro-functionalized virtual human body model Yoon-Sun, and to estimate the current threshold to induce magnetic stimulation (MS) of the radial nerve. Eleven healthy subjects were studied with the mcoil, which consisted of two 15 mm diameter coils in a figure-of-eight configuration, each with a hundred turns of a 25 μm copper-clad four-layer foil. Sensory nerve action potentials (SNAPs) were measured in each subject using two electrodes and compared with those obtained from standard ES. The SNAPs conduction velocities were estimated as a performance metric. RESULTS The induced electric field was estimated numerically to peak at a maximum intensity of 39 V/m underneath the mcoil fed by 70 A currents. In such conditions, the electrophysiological simulations suggested that the mcoil elicits SNAPs originating at 7 mm from the center of the mcoil. Furthermore, the numerically estimated latencies and waveforms agreed with those obtained during the PMS experiments on healthy subjects, confirming the ability of the mcoil to stimulate the radial nerve sensory fibers. CONCLUSION Hybrid EM-electrophysiological simulations assisted the development of a miniaturized coil with a small diameter and a high number of turns using flexible electronics. The numerical dosimetric analysis predicted the threshold current amplitudes required for a suprathreshold peripheral nerve sensory stimulation, which was experimentally confirmed. The developed and now validated computational pipeline will be used to improve the performances (e.g., focality and minimal currents) of new generations of mcoil designs.
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Affiliation(s)
- Micol Colella
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Information Engineering, Electronics and Telecommunications (DIET), Sapienza University of Rome, Rome, Italy
| | - Daniel Z. Press
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Rebecca M. Laher
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Courtney E. McIlduff
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Seward B. Rutkove
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Antonino M. Cassarà
- IT'IS Foundation for Research on Information Technologies in Society, 8004 Zurich, Switzerland
| | - Francesca Apollonio
- Department of Information Engineering, Electronics and Telecommunications (DIET), Sapienza University of Rome, Rome, Italy
| | - Alvaro Pascual-Leone
- Hinda and Arthur Marcus Institute for Aging Research and Center for Memory Health, Hebrew SeniorLife, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
- Guttmann Brain Health Institut, Institut Guttmann, Universitat Autonoma Barcelona, Spain
| | - Micaela Liberti
- Department of Information Engineering, Electronics and Telecommunications (DIET), Sapienza University of Rome, Rome, Italy
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
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