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Nakayama K, Kohara N, Paku M, Sato S, Nakamura M, Ando M, Taniguchi S, Ishihara M, Tani Y, Itakura T, Saito T, Yakushiji Y. Visualization of axonal and volume currents in median nerve compound action potential using magnetoneurography. Clin Neurophysiol 2023; 152:57-67. [PMID: 37307628 DOI: 10.1016/j.clinph.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/26/2023] [Accepted: 05/05/2023] [Indexed: 06/14/2023]
Abstract
OBJECTIVE Reconstruct compound median nerve action currents using magnetoneurography to clarify the physiological characteristics of axonal and volume currents and their relationship to potentials. METHODS The median nerves of both upper arms of five healthy individuals were investigated. The propagating magnetic field of the action potential was recorded using magnetoneurography, reconstructed into a current, and analyzed. The currents were compared with the potentials recorded from multipolar surface electrodes. RESULTS Reconstructed currents could be clearly visualized. Axonal currents flowed forward or backward in the axon, arcing away from the depolarization zone, turning about the subcutaneous volume conductor, and returning to the depolarization zone. The zero-crossing latency of the axonal current was approximately the same as the peak of its volume current and the negative peak of the surface electrode potential. Volume current waveforms were proportional to the derivative of axonal ones. CONCLUSIONS Magnetoneurography allows the visualization and quantitative evaluation of action currents. The currents in axons and in volume conductors could be clearly discriminated with good quality. Their properties were consistent with previous neurophysiological findings. SIGNIFICANCE Magnetoneurography could be a novel tool for elucidating nerve physiology and pathophysiology.
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Affiliation(s)
- Kentaro Nakayama
- Department of Neurology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Nobuo Kohara
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan; Department of Neurology, Kobe City Medical Center General Hospital, 2-1-1 Minatojima Minamimachi, Chuo-ku, Kobe 650-0047, Japan.
| | - Masaaki Paku
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Shinji Sato
- RICOH Futures BU, RICOH Company, Ltd., 2-3-10 Kandasurugadai Chiyoda-ku, Tokyo 101-0062, Japan
| | - Masataka Nakamura
- Department of Neurology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Muneharu Ando
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Shinichirou Taniguchi
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Masayuki Ishihara
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Yoichi Tani
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Takeshi Itakura
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Takanori Saito
- Department of Orthopedic Surgery, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
| | - Yusuke Yakushiji
- Department of Neurology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka 573-1010, Japan
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Detailed magnetoelectric analysis of a nerve impulse propagation along the brachial plexus. Clin Neurophysiol 2023; 145:129-138. [PMID: 36280574 DOI: 10.1016/j.clinph.2022.09.018] [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: 05/02/2022] [Revised: 09/02/2022] [Accepted: 09/25/2022] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To visualize impulse conduction along the brachial plexus through simultaneous electromagnetic measurements. METHODS Neuromagnetic fields following median nerve stimulation were recorded above the clavicle with a superconducting quantum interference device biomagnetometer system in 7 healthy volunteers. Compound nerve action potentials (CNAPs) were obtained from 12 locations. Pseudocolor maps of equivalent currents reconstructed from magnetic fields and isopotential contour maps were superimposed onto X-ray images. Surface potentials and current waveforms at virtual electrodes along the brachial plexus were compared. RESULTS In magnetic field analysis, the leading axonal current followed by a trailing backward current traveled rostrally along the brachial plexus. The spatial extent of the longitudinal intra-axonal currents corresponded to the extent of the positive-negative-positive potential field reflecting transmembrane volume currents. The peaks and troughs of the intra-axonal biphasic current waveforms coincided with the zero-crossings of triphasic CNAP waveforms. The amplitudes of CNAPs and current moments were linearly correlated. CONCLUSIONS Reconstructed neural activity in magnetic field analysis visualizes not only intra-axonal currents, but also transmembrane volume currents, which are in good agreement with the surface potential field. SIGNIFICANCE Magnetoneurography is a novel non-invasive functional imaging modality for the brachial plexus whose performance can surpass that of electric potential measurement.
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Bu Y, Prince J, Mojtahed H, Kimball D, Shah V, Coleman T, Sarkar M, Rao R, Huang M, Schwindt P, Borna A, Lerman I. Peripheral Nerve Magnetoneurography With Optically Pumped Magnetometers. Front Physiol 2022; 13:798376. [PMID: 35370794 PMCID: PMC8975546 DOI: 10.3389/fphys.2022.798376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Electrodiagnosis is routinely integrated into clinical neurophysiology practice for peripheral nerve disease diagnoses, such as neuropathy, demyelinating disorders, nerve entrapment/impingement, plexopathy, or radiculopathy. Measured with conventional surface electrodes, the propagation of peripheral nerve action potentials along a nerve is the result of ionic current flow which, according to Ampere’s Law, generates a small magnetic field that is also detected as an “action current” by magnetometers, such as superconducting quantum interference device (SQUID) Magnetoencephalography (MEG) systems. Optically pumped magnetometers (OPMs) are an emerging class of quantum magnetic sensors with a demonstrated sensitivity at the 1 fT/√Hz level, capable of cortical action current detection. But OPMs were ostensibly constrained to low bandwidth therefore precluding their use in peripheral nerve electrodiagnosis. With careful OPM bandwidth characterization, we hypothesized OPMs may also detect compound action current signatures consistent with both Sensory Nerve Action Potential (SNAP) and the Hoffmann Reflex (H-Reflex). In as much, our work confirms OPMs enabled with expanded bandwidth can detect the magnetic signature of both the SNAP and H-Reflex. Taken together, OPMs now show potential as an emerging electrodiagnostic tool.
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Affiliation(s)
- Yifeng Bu
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
| | - Jacob Prince
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
| | - Hamed Mojtahed
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
| | - Donald Kimball
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
| | | | - Todd Coleman
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Mahasweta Sarkar
- Electrical and Computer Engineering Department, San Diego State University, Stanford, CA, United States
| | - Ramesh Rao
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
| | - Mingxiong Huang
- Department of Radiology, Radiology Imaging Laboratory, University of California San Diego, San Diego, CA, United States
| | - Peter Schwindt
- Quantum Information Sciences, Sandia National Laboratories, Albuquerque, NM, United States
| | - Amir Borna
- Quantum Information Sciences, Sandia National Laboratories, Albuquerque, NM, United States
| | - Imanuel Lerman
- Jacobs School of Engineering, Electrical and Computer Engineering, University of California San Diego, San Diego, CA, United States
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego, San Diego, CA, United States
- Veterans Health Administration, VA San Diego, Center for Stress and Mental Health, San Diego, CA, United States
- *Correspondence: Imanuel Lerman,
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Thalamocortical Impulse Propagation and Information Transfer in EEG and MEG. J Clin Neurophysiol 2014; 31:253-60. [DOI: 10.1097/wnp.0000000000000048] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Ishii S, Kawabata S, Tomizawa S, Tomori M, Sakaki K, Shinomiya K, Sekihara K, Sato T, Adachi Y, Okawa A. Conductive neuromagnetic fields in the lumbar spinal canal. Clin Neurophysiol 2012; 123:1656-61. [PMID: 22285173 DOI: 10.1016/j.clinph.2011.12.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 12/17/2011] [Accepted: 12/23/2011] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To measure neuromagnetic evoked fields in the lumbar spinal canal. METHODS Using a newly developed superconducting quantum interference device (SQUID) fluxmeter, neuromagnetic fields of 5 healthy male volunteers were measured at the surface of the lower back after stimulation of the tibial nerves at the ankles. For validation, we inserted a catheter-type electrode percutaneously in the lumbar epidural space in 2 of the subjects and measured cauda equina action potentials after tibial nerve stimulation. RESULTS Neuromagnetic fields propagating from the intervertebral foramina into the spinal canal were measured, and the latencies of the magnetic fields corresponded largely with those of the cauda equina action potentials. CONCLUSIONS We successfully measured ascending neuromagnetic fields originating at the nerve root and the cauda equina with high spatial resolution. Future studies will determine whether neuromagnetic field measurement of the lumbar spine can be a useful diagnostic method for the identification of the disordered site in spinal nerves. SIGNIFICANCE We successfully measured neuromagnetic fields in the lumbar spinal canal, which have previously been difficult to verify. Future studies will determine whether neuromagnetic field measurement of the lumbar spine can be a useful diagnostic method for identifying disorders of spinal nerves.
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Affiliation(s)
- Senichi Ishii
- Department of Frontier Surgical Therapeutics, Section of Orthopedic and Spinal Surgery, Division of Advanced Therapeutical Sciences, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan
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Papadelis C, Leonardelli E, Staudt M, Braun C. Can magnetoencephalography track the afferent information flow along white matter thalamo-cortical fibers? Neuroimage 2012; 60:1092-105. [PMID: 22266410 DOI: 10.1016/j.neuroimage.2012.01.054] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 11/27/2011] [Accepted: 01/05/2012] [Indexed: 11/19/2022] Open
Abstract
White matter thalamo-cortical fibers allow the communication of distant brain regions by carrying neuronal signals. Mapping non-invasively the information flow within white matter fibers is regarded so far as impossible. We investigated here whether information flow propagating along thalamo-cortical fibers can be detected using magnetoencephalography (MEG). Somatosensory evoked fields (SEFs) were recorded from healthy subjects and a patient with a unilateral, prenatally acquired, white matter lesion, which had induced the development of an abnormal trajectory of thalamo-cortical fibers. Equivalent current dipole (ECD) was used to model sources of SEFs. ECD at ~15 ms after stimulus onset was located within or close to the contralateral thalamus at the proximity of a hemodynamic response detected during a similar fMRI experiment. At the M20 peak latency, ECD was localized within the hand area of the contralateral primary somatosensory cortex (Brodmann area 3b (BA3b)). In healthy subjects, ECD changed dynamically position from thalamus to BA3b following a curved path, which was partially overlapping the thalamo-cortical fibers reconstructed by tractography. In the patient, ECD followed a similar path only in the intact hemisphere. In the affected hemisphere, the dipole trajectory circumnavigated the extended lesion on its way to the preserved primary somatosensory cortex--similar to the trajectory findings. Evidence from different methodological approaches converges on the conclusion that MEG can track the afferent information flow along thalamo-cortical fibers and in contrast to the traditional view can localize under presuppositions deep thalamic sources.
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Affiliation(s)
- Christos Papadelis
- Center for Mind/Brain Sciences-CIMeC, University of Trento, Via delle Regole 101, I-38100 Mattarello, Italy.
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Diagnosis of incomplete conduction block of spinal cord from skin surface using spinal cord evoked magnetic fields. J Orthop Sci 2010; 15:371-80. [PMID: 20559806 DOI: 10.1007/s00776-010-1463-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND We previously reported the usefulness of neuromagnetic recordings for the diagnosis of disorders in peripheral nerves or the spinal cord. However, there have been no reports on incomplete conduction block of the spinal cord, which is clinically common in conditions such as cervical myelopathy. Here, we estimated the usefulness of measuring spinal cord evoked magnetic fields for evaluating incomplete conduction block. METHODS Incomplete conduction block models of the spinal cord of the rabbit were established using a Fogarty balloon catheter that was inserted into the epidural space of the cervical spine. Electrical stimuli were applied to the lower thoracic spinal cord with an epidural catheter electrode. Spinal cord evoked potentials were recorded using epidural electrodes. Spinal cord evoked magnetic fields were recorded over the skin surface of the neck using a biomagnetometer. RESULTS The decrease in the conduction velocity and amplitude at the compression site could be detected by spinal cord evoked potentials from the epidural space, confirming the spinal cord lesion. The waveforms of the magnetic fields showed a biphasic configuration. The distribution of magnetic fields showed a characteristic quadrupolar pattern propagating from caudal to cranial. After compression, the amplitude and the conduction velocity of the magnetic fields decreased, and the distribution of magnetic fields were attenuated and decelerated near the compression site especially in the trailing magnetic fields. Diagnosis of the incomplete conduction block was thus possible. CONCLUSIONS We report the first measurement of the spinal cord evoked magnetic field in the intact spinal cord from the skin surface and that it can be applied to incomplete conduction block of the injured spinal cord. The use of a biomagnetometer is promising as a less-invasive method for clinically evaluating spinal cord function.
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Impulse propagation along thalamocortical fibers can be detected magnetically outside the human brain. J Neurosci 2009; 28:12535-8. [PMID: 19020045 DOI: 10.1523/jneurosci.3022-08.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Orchestrating cortical network activity with synchronous oscillations of neurons across distant regions of the brain underlies information processing in humans (Knight, 2007) and monkeys (Saalmann et al., 2007; Womelsdorf et al., 2007). Frequencies of oscillatory activities depend, to a considerable extent, on the length and conduction velocity of the tracts connecting the neural areas that participate in oscillations (Buzsáki, 2006). However, the impulse propagation along the fiber tracts in the white matter has never been visualized in humans. Here, we show, by recording magnetoencephalogram (MEG) following median nerve stimulation, that a magnetic field component, we labeled "M15," changes dynamically within 1.6-1.8 ms before the onset of magnetic M20 response generated from the primary somatosensory cortex. This new M15 component corresponds to the intracellular depolarizing action current in the thalamocortical fibers propagating with the mean conduction velocity of 29 m/s. The findings challenge the traditional view that MEG is blind to the activity of deep subcortical structures. We argue that the MEG technique holds the promise of providing novel information in impulse transmissions along not only the thalamocortical pathway but also other fiber tracts connecting distant brain areas in humans.
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Evaluation of segmental spinal cord evoked magnetic fields after sciatic nerve stimulation. Clin Neurophysiol 2008; 119:1111-8. [PMID: 18337167 DOI: 10.1016/j.clinph.2008.01.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 12/28/2007] [Accepted: 01/14/2008] [Indexed: 11/21/2022]
Abstract
OBJECTIVE We have previously reported that the measurement of spinal cord evoked magnetic fields (SCEFs) could be a helpful method for evaluating spinal cord function or detecting conduction blocks in the spinal cord. However, there have been no reports about segmental-SCEFs as a complex of axonal and synaptic activities in the spinal cord. The purpose of this study is to record and evaluate segmental-SCEFs. METHODS The segmental-SCEFs were measured over the lumbar dural tubes of adult rabbits using our SQUID system following sciatic nerve stimulation; spinal cord evoked potentials (SCEPs) were also measured to compare the results. RESULTS SCEPs showed conductive sharp waves following gentle waves, suggesting action potentials and synaptic potentials, respectively. The isomagnetic field maps of SCEFs showed a quadrupolar pattern propagating from the caudal to the cranial region within a short latency time, and after the conductive magnetic fields passed, stationary dipolar fields appeared and were sustained at some vertebral levels. CONCLUSIONS The quadrupolar magnetic fields were estimated to be generated from conducting action potentials, and the dipolar fields were thought to be caused by synaptic activities. SIGNIFICANCE Through the measurement of segmental-SCEFs, the conductive neural and synaptic activities in the spinal cord can be visualized and distinguished. This is the first report to record and visualize the sequence of events ranging from the axonal activities of peripheral nerves and the spinal tract to the synaptic activities in the spinal cord.
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Nakanishi K, Fujimoto Y, Tanaka N, Iwase Y, Inoue K, Ishida O, Ochi M. Visualization of temporal increase in compound nerve action magnetic fields in the human median nerve during ischemia. Neuroimage 2005; 25:642-5. [PMID: 15784443 DOI: 10.1016/j.neuroimage.2004.11.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Revised: 05/26/2004] [Accepted: 11/30/2004] [Indexed: 10/25/2022] Open
Abstract
We studied the variation in the human median nerve activity during ischemia by measuring compound nerve action magnetic fields (CAFs). Temporal increases in the CAF during ischemia were successfully visualized on isofield contour maps. Intense paresthesias were induced after 29 +/- 5 s (mean +/- SD) of ischemia, which consistently reached a maximum after 4 min 55 +/- 12 s. The variations in CAFs were consistent with changes in sensory perception. The hyperexcitability in large myelinated axons can be visualized as temporary increases in CAF. These results are the first to demonstrate the efficacy of magnetic-recording techniques, which allow monitoring of changes in neural activity.
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Affiliation(s)
- Kazuyoshi Nakanishi
- Department of Orthopaedic Surgery, Programs for Applied Biomedicine, Division of Clinical Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan.
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Mackert BM. Magnetoneurography: theory and application to peripheral nerve disorders. Clin Neurophysiol 2004; 115:2667-76. [PMID: 15546775 DOI: 10.1016/j.clinph.2004.07.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2004] [Indexed: 11/23/2022]
Abstract
Magnetoneurography (MNG) is a non-invasive method to trace and visualize three-dimensionally the propagation path of compound action currents (CAC) along peripheral nerves. The basic physical and physiological principle is the mapping of extremely weak magnetic fields generated by the intraaxonal longitudinal ion flows of evoked nerval CAC using SQUID sensors (Superconducting Quantum Interference Devices). During recent years, MNG protocols have been established which allow for a non-invasive spatiotemporal tracing of impulse propagation along peripheral nerves in humans and in particular along proximal nerve segments in a clinical setting. Thereby, the three-dimensional path, the local nerve conduction velocity, the length and strength of the CAC de- and repolarization phase have been reconstructed. First recordings in patients demonstrated that the method is sensitive enough to detect and to localize nerve conduction anomalities along nerve roots, as, e.g. caused by lumbosacral disc herniation. This review on MNG will focus on those studies which provide data from humans and thereby reveal perspectives for its future clinical applications.
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Affiliation(s)
- Bruno-Marcel Mackert
- Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Hindenburgdamm 30, 12200 Berlin, Germany.
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Fukuoka Y, Komori H, Kawabata S, Ohkubo H, Shinomiya K. Visualization of incomplete conduction block by neuromagnetic recording. Clin Neurophysiol 2004; 115:2113-22. [PMID: 15294213 DOI: 10.1016/j.clinph.2004.03.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE We previously reported on evoked compound action magnetic fields (CAFs) in isolated sciatic nerves with complete conduction block. In this study, we examined evoked CAFs of the nerve with incomplete conduction block, which is clinically common. METHODS Rabbits' isolated nerves were electrically stimulated in a chamber containing Ringer's solution. Compound action potentials (CAPs) and CAFs were recorded before and after the incomplete conduction block induced by a vascular clip. The positions of the lesion were estimated by dipole localization. RESULTS Before the nerve clipping, magnetic contour maps showed CAFs with a characteristic quadrupolar pattern. After the clipping, CAFs attenuated in the amplitude and decelerated through the lesion. Estimated position of the lesion was 0.12+/-3.23 mm (mean+/-SD, n=10) assuming that the real position of the clip was 0 mm. CONCLUSIONS The time-course of changes of CAFs in the incomplete conduction block was visualized by magnetic contour maps, and the lesions were closely localized focusing on the velocity change of the leading dipole. SIGNIFICANCE The neural conduction with incomplete conduction block was visualized and the lesion was closely localized by neuromagnetic recordings.
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Affiliation(s)
- Yuko Fukuoka
- Department of Frontier Surgical Therapeutics, Section of Orthopedic and Spinal Surgery, Division of Advanced Therapeutical Sciences, Graduate School of Tokyo Medical and Dental University, Japan.
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Nakanishi K, Mashiko T, Fujimoto Y, Tanaka N, Iwase Y, Ishida O, Ochi M. Wide-range visualization of compound nerve action magnetic fields in the human median and ulnar nerves from the forearm to Erb's point. Neurosci Lett 2004; 356:151-3. [PMID: 14746886 DOI: 10.1016/j.neulet.2003.11.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We successfully visualized the compound nerve action magnetic fields (CAFs) in the human median and ulnar nerves from the forearm to Erb's point. To observe the CAFs, we used a superconducting quantum interference device gradiometer system that was developed for human peripheral nerves. The CAFs were visualized as a quadrupole pattern consisting of leading and trailing dipoles. The CAFs propagated along the anatomical pathway and extended longitudinally in the proximal segment. The most reasonable explanation is that the peak separation in the trailing dipole appeared when the leading dipole reached the proximal segment after stimulation of the median nerve at the wrist. A temporal dispersion of the CAFs was suggested to be visualized.
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Affiliation(s)
- Kazuyoshi Nakanishi
- Department of Orthopaedic Surgery, Programs for Applied Biomedicine, Division of Clinical Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan.
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Fukuoka Y, Komori H, Kawabata S, Ohkubo H, Shinomiya K, Terasaki O. Imaging of neural conduction block by neuromagnetic recording. Clin Neurophysiol 2002; 113:1985-92. [PMID: 12464338 DOI: 10.1016/s1388-2457(02)00345-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE For the clinical application of neuromagnetic recordings in neural conduction block, the patterns of magnetic fields in the region should be clarified. Using an experimental in vitro model, the spatiotemporal course of the neuromagnetic fields at the site of complete conduction block was examined. Additionally, the magnetic compound action fields (CAFs) and electric compound action potentials (CAPs) were compared and correlated. METHODS In a chamber containing Ringer's solution, 10 isolated sciatic nerves of rabbits were electrically stimulated. Both evoked CAPs and CAFs were measured before and after the ligation of the nerve. The sequential positions of the current dipoles and the location of the conduction block were estimated by the least-squares search. RESULTS The magnetic contour maps of the CAFs showed a characteristic quadrupolar pattern propagating along the nerve. The peak of the leading magnetic field ceased and disappeared at the position of the nerve ligation, while the trailing magnetic field became attenuated before reaching that position. The positions of the conduction blocks were localized by magnetic recordings within a difference of 2mm. CONCLUSIONS The neuromagnetic recordings could visualize the change of the magnetic fields at the site of the complete conduction block and closely localize that position. SIGNIFICANCE The neural conduction block was visualized and localized by neuromagnetic recordings.
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Affiliation(s)
- Yuko Fukuoka
- Section of Orthopedic Spinal Surgery, Department of Frontier Surgical Therapeutics, Division of Advanced Therapeutical Sciences, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan.
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Kawabata S, Komori H, Mochida K, Harunobu O, Shinomiya K. Visualization of conductive spinal cord activity using a biomagnetometer. Spine (Phila Pa 1976) 2002; 27:475-9. [PMID: 11880832 DOI: 10.1097/00007632-200203010-00007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN The authors measured conductive cervical spinal cord evoked magnetic fields (SCEFs) after thoracic spinal cord stimulation in cats and visualized spinal cord activities. OBJECTIVE To evaluate the usefulness of magnetic field measurement. SUMMARY OF BACKGROUND DATA Magnetic field measurement has several theoretical advantages compared with electric potential measurement. Although biomagnetometers for the brain and heart are already on the market and are widely used, methods for magnetic field measurement of the spinal cord have not been established. METHOD Cervical laminectomy was performed on adult cats under anesthesia and the dural tube was exposed. Electrical stimuli were applied to the lower thoracic spinal cord by a catheter epidural electrode. SCEFs were recorded using a biomagnetometer specially designed for recording spinal cord action potentials. SCEFs were measured at 35 different points over the cervical spine and isomagnetic field maps of SCEFs were constructed. Thereafter, the spinal cord was transected completely at C5 and SCEFs were measured again. RESULTS The detected SCEFs showed a clear biphasic configuration. The first deflection of the magnetic fields from the left side was directed outward, but the right-side deflection was directed inward. The second deflection showed reversed polarity. The isomagnetic field maps of SCEFs clearly demonstrated the quadrupolar pattern and propagated at a conduction velocity of 80-120 m/s. After spinal cord transection, the propagation of SCEFs stopped at the transection site, and the SCEFs could not be obtained above the site. CONCLUSIONS The authors concluded that magnetic field measurement is useful for evaluation of spinal cord function. Moreover, it was apparent that SCEFs could indicate conduction block in the spinal cord.
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Affiliation(s)
- Shigenori Kawabata
- Section of Orthopaedic Spinal Surgery, Department of Frontier Surgical Therapeutics, Division of Advanced Therapeutical Sciences Graduate School, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
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Mackert BM, Burghoff M, Hiss LH, Nordahn M, Marx P, Trahms L, Curio G. Magnetoneurography of evoked compound action currents in human cervical nerve roots. Clin Neurophysiol 2001; 112:330-5. [PMID: 11165538 DOI: 10.1016/s1388-2457(00)00530-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE A measurement protocol for magnetoneurography (MNG) is established which allows the non-invasive localization and tracing of evoked compound action currents propagating along cervical nerve roots in man. METHODS Inside a magnetically shielded room either both median or both ulnar nerves of healthy subjects were conventionally electrostimulated in alternation. Evoked magnetic responses were recorded using a multichannel SQUID-detector with a planar measuring area centered over the neck. Simultaneously, electric surface potentials were recorded using cervical bipolar electrode montages. RESULTS Upon median (ulnar) nerve stimulation somatosensory evoked magnetic fields up to 20 fT (10 fT) amplitude were detected propagating over the cervical transforaminal root entry zone, with corresponding electrical surface potentials of 1.5 microV (0.5 microV). Furthermore, the signal-to-noise ratio of the spatiotemporal magnetic field mappings in median nerve stimulation experiments allowed dipolar source reconstructions and tracing of the propagation of the compound action currents along nerve root fibers. CONCLUSION Magnetoneurography allows tracing of the propagation of evoked compound action currents along cervical roots in healthy subjects with millisecond temporal and high spatial resolution. Thus, MNG offers a sensitivity appropriate to serve as a clinical diagnostic tool for localizing focal neuropathies of cervical nerve roots.
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Affiliation(s)
- B M Mackert
- Neurophysics Group, Klinikum Benjamin Franklin, Freie Universität, 12203, Berlin, Germany.
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Kakigi R, Hoshiyama M, Shimojo M, Naka D, Yamasaki H, Watanabe S, Xiang J, Maeda K, Lam K, Itomi K, Nakamura A. The somatosensory evoked magnetic fields. Prog Neurobiol 2000; 61:495-523. [PMID: 10748321 DOI: 10.1016/s0301-0082(99)00063-5] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Averaged magnetoencephalography (MEG) following somatosensory stimulation, somatosensory evoked magnetic field(s) (SEF), in humans are reviewed. The equivalent current dipole(s) (ECD) of the primary and the following middle-latency components of SEF following electrical stimulation within 80-100 ms are estimated in area 3b of the primary somatosensory cortex (SI), the posterior bank of the central sulcus, in the hemisphere contralateral to the stimulated site. Their sites are generally compatible with the homunculus which was reported by Penfield using direct cortical stimulation during surgery. SEF to passive finger movement is generated in area 3a or 2 of SI, unlike with electrical stimulation. Long-latency components with peaks of approximately 80-120 ms are recorded in the bilateral hemispheres and their ECD are estimated in the secondary somatosensory cortex (SII) in the bilateral hemispheres. We also summarized (1) the gating effects on SEF by interference tactile stimulation or movement applied to the stimulus site, (2) clinical applications of SEF in the fields of neurosurgery and neurology and (3) cortical plasticity (reorganization) of the SI. SEF specific to painful stimulation is also recorded following painful stimulation by CO(2) laser beam. Pain-specific components are recorded over 150 ms after the stimulus and their ECD are estimated in the bilateral SII and the limbic system. We introduced a newly-developed multi (12)-channel gradiometer system with the smallest and highest quality superconducting quantum interference device (micro-SQUID) available to non-invasively detect the magnetic fields of a human peripheral nerve. Clear nerve action fields (NAFs) were consistently recorded from all subjects.
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Affiliation(s)
- R Kakigi
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan.
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Mackert BM, Burghoff M, Hiss LH, Nordahn M, Trahms L, Curio G. Non-invasive magnetoneurography for 3D-monitoring of human compound action current propagation in deep brachial plexus. Neurosci Lett 2000; 289:33-6. [PMID: 10899402 DOI: 10.1016/s0304-3940(00)01249-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Compound action current (CAC) propagation along nerve fibers running deep in the human brachial plexus was 3D-visualized based on non-invasive 49-channel superconducting quantum interference device (SQUID) magnetoneurography. Spatio-temporal mappings over the upper thoracal quadrant of magnetic fields (<100 fT) evoked upon alternating median and ulnar nerve stimulation in seven healthy volunteers showed consistently smoothly propagating dipolar patterns for both the CAC depolarization and repolarization phases. Multipolar current source reconstructions (i) distinguished spatially CAC propagation pathways along either median or ulnar plexus fibers, allowed (ii) to calculate local conduction velocities ( approximately 56 m/s) and (iii) even to estimate the CAC extension along the nerve fibers (depolarization phase: approximately 11 cm). Thus, for deep proximal nerve segments magnetoneurography can provide a detailed tracing of neural activity which is a prerequisite to localize non-invasively focal nerve malfunctions.
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Affiliation(s)
- B M Mackert
- Neurophysics Group, Department of Neurology, Klinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12203, Berlin, Germany.
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Abstract
A short review of previous studies is presented on somatic, evoked high-frequency oscillations. Also described briefly is recent data on the detection of high-frequency oscillations to posterior tibial nerve stimulation, and also on both tangential (area 3b) and radial (area 1) dipoles to median nerve stimulation. The findings show that high-frequency oscillations are not specific to median nerve stimulation but represent ubiquitous activity in the primary somatosensory cortex. Modulation of high-frequency oscillations versus electric and magnetic N20, N20 (m), primary response by a wake-sleep cycle, by attention or interference, by aging, and in central nervous system diseases such as Parkinson's disease and myoclonus epilepsy are also presented. Finally, a gamma-aminobutyric acid inhibitory interneuron hypothesis is presented for high-frequency oscillations based primarily on the findings regarding reciprocal modulation of the high-frequency oscillations and the underlying magnetic N20 (N20m) by a wake-sleep cycle and by attention or interference.
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Affiliation(s)
- I Hashimoto
- Human Information Systems Laboratories (Tokyo Office), Kanazawa Institute of Technology, Japan.
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Hoshiyama M, Kakigi R, Nagata O. Peripheral nerve conduction recorded by a micro gradiometer system (micro-SQUID) in humans. Neurosci Lett 1999; 272:199-202. [PMID: 10505615 DOI: 10.1016/s0304-3940(99)00589-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We developed a new multi (twelve) -channel gradiometer system with the smallest and highest quality superconducting quantum interference device (micro-SQUID). A very small distance (3.80 mm) between the sensor coils and the skin provides quite high spatial resolution. The actual whole image of the sensory nerve action fields (NAF) of the human median nerve at the wrist were successfully recorded following digital nerve stimulation by using the micro-SQUID. The NAF showed the biphasic waveform at each of the 12 channels, and the isomagnetic field map clearly showed the moving quadrupole pattern. The quadrupole comprised a dipole for depolarization followed by another dipole with the opposite direction for repolarization. The polarized length of the nerve obtained by reconstructing the magnetic field maps was approximately 17 cm, and the magnetic field complex moved along the nerve from the distal to the proximal part of the wrist at 58.7 m/s.
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Affiliation(s)
- M Hoshiyama
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan.
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Hashimoto I, Kimura T, Fukushima T, Iguchi Y, Saito Y, Terasaki O, Sakuma K. Reciprocal modulation of somatosensory evoked N20m primary response and high-frequency oscillations by interference stimulation. Clin Neurophysiol 1999; 110:1445-51. [PMID: 10454280 DOI: 10.1016/s1388-2457(99)00083-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES We examined whether the inverse relation between somatic evoked N20m primary response and high-frequency oscillations during a wake-sleep cycle (Hashimoto, I., Mashiko, T., Imada, T., Somatic evoked high-frequency magnetic oscillations reflect activity of inhibitory interneurons in the human somatosensory cortex, Electroenceph clin Neurophysiol 1996;100:189-203) holds for interference stimulation. METHODS Somatosensory evoked fields (SEFs) from 14 subjects were measured following electric median nerve stimulation at the wrist with, and without, concurrent brushing of the palm and fingers. SEFs were recorded with a wide bandpass (0.1-1200 Hz) and then N20m and high-frequency oscillations were separated by subsequent low-pass (< 300 Hz) and high-pass (> 300 Hz) filtering. RESULTS The N20m decreased dramatically in amplitude during interference stimulation. In contrast, the high-frequency oscillations moderately increased in number of peaks. CONCLUSIONS These results demonstrate the presence of an inverse relation between N20m and high-frequency oscillations for interference stimulation. We speculate that the high-frequency oscillations represent a localized activity of GABAergic inhibitory interneurons of layer 4, characterized by a high-frequency spike burst (200-1000 Hz) without adaptation, and that the continuous interference stimulation induces tonic excitation of the interneurons, leading to a facilitation of responses to the coherent afferent volley elicited by the median nerve stimulation (bottom-up mechanism). On the other hand, refractoriness of the pyramidal neurons caused directly by interference stimulation along with an enhanced feed-forward inhibition from the interneurons will lead to a decrease of N20m amplitude.
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Affiliation(s)
- I Hashimoto
- Department of Psychophysiology, Tokyo Institute of Psychiatry, Japan.
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Mackert BM, Curio G, Burghoff M, Marx P. Mapping of tibial nerve evoked magnetic fields over the lower spine. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1997; 104:322-7. [PMID: 9246069 DOI: 10.1016/s0168-5597(97)00019-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Using a low-noise 49-channel dc-SQUID system spinal somatosensory evoked fields (SEF) were recorded which were generated by compound action currents evoked upon posterior tibial nerve stimulation. The SEF mapping showed the action current propagation along the sciatic nerve, lumbosacral plexus and cauda equina in parallel to simultaneously recorded electrical potentials (SEP). For a reliable intraindividual side-to-side comparison of spinal SEFs the right and left tibial nerves were stimulated in alternating order; this procedure minimizes artifactual inter-nerve SEF map differences due to eventual patient-to-sensor displacements which might occur in serial measurements. These large-area lumbar SEF mappings open up several clinical perspectives for magnetoneurography, in particular with respect to the 3D-localization of proximal conduction blocks.
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Affiliation(s)
- B M Mackert
- Department of Neurology, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Germany
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Hashimoto I, Mashiko T, Mizuta T, Imada T, Iwase Y, Okazaki H, Yoshikawa K. Multichannel detection of magnetic compound action fields with stimulation of the index and little fingers. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1995; 97:102-13. [PMID: 7537202 DOI: 10.1016/0924-980x(94)00287-h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Magnetic compound action fields (CAFs) over the right arm were measured from 63 sensor positions with two 7-channel SQUID gradiometer systems following electrical stimulation of the index and little fingers as well as the ring finger separately. The wave forms of the CAFs were primarily biphasic, corresponding to the depolarization and repolarization currents of the stimulated nerves. Maximum amplitudes of the CAFs were 60-140 fT for the index finger stimulation and 40-90 fT for the little finger stimulation. The field mapping of the CAFs revealed a propagating quadrupolar pattern with different distributions for the index and little fingers. The results agree with the anatomical location of the median and ulnar nerves for the index and little finger stimulation respectively. The isofield maps, due to ring finger stimulation, showed complex patterns as a result of simultaneous activation of the median and ulnar nerves. By comparing the amplitudes of the maxima of the CAFs due to index finger stimulation with those after median nerve stimulation at the wrist, the numerical ratios of the constituent digital nerve fibers for the index finger within the median nerve at the wrist were estimated. The ratios of 0.14-0.41 (mean 0.27), determined with measurement of the CAFs, are fairly consistent with those calculated from the reported histological data.
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Affiliation(s)
- I Hashimoto
- Department of Psychophysiology, Tokyo Institute of Psychiatry, Japan
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