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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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Schneider C, Zangrandi A, Sollmann N, Bonfert MV, Beaulieu LD. Checklist on the Quality of the Repetitive Peripheral Magnetic Stimulation (rPMS) Methods in Research: An International Delphi Study. Front Neurol 2022; 13:852848. [PMID: 35392633 PMCID: PMC8981720 DOI: 10.3389/fneur.2022.852848] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/28/2022] [Indexed: 12/24/2022] Open
Abstract
An increasing number of clinical research studies have used repetitive peripheral magnetic stimulation (rPMS) in recent years to alleviate pain or improve motor function. rPMS is non-invasive, painless, and administrated over peripheral nerve, spinal cord roots, or a muscle using a coil affixed to the skin and connected to a rapid-rate magnetic stimulator. Despite the clinical impact and scientific interest, the methodological inconsistencies or incomplete details and findings between studies could make the rPMS demonstration difficult to replicate. Given the lack of guidelines in rPMS literature, the present study aimed at developing a checklist to improve the quality of rPMS methods in research. An international panel of experts identified among those who had previously published on the topic were enrolled in a two-round web-based Delphi study with the aim of reaching a consensus on the items that should be reported or controlled in any rPMS study. The consensual rPMS checklist obtained comprises 8 subject-related items (e.g., age, sex), 16 methodological items (e.g., coil type, pulse duration), and 11 stimulation protocol items (e.g., paradigm of stimulation, number of pulses). This checklist will contribute to new interventional or exploratory rPMS research to guide researchers or clinicians on the methods to use to test and publish rPMS after-effects. Overall, the checklist will guide the peer-review process on the quality of rPMS methods reported in a publication. Given the dynamic nature of a consensus between international experts, it is expected that future research will affine the checklist.
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Affiliation(s)
- Cyril Schneider
- Noninvasive Stimulation Laboratory (NovaStim), Neuroscience Division, Research Center of CHU de Québec-Université Laval, Quebec City, QC, Canada
- Department of Rehabilitation, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
- *Correspondence: Cyril Schneider
| | - Andrea Zangrandi
- Noninvasive Stimulation Laboratory (NovaStim), Neuroscience Division, Research Center of CHU de Québec-Université Laval, Quebec City, QC, Canada
- Department of Rehabilitation, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
| | - Nico Sollmann
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States
| | - Michaela Veronika Bonfert
- Division of Pediatric Neurology and Developmental Medicine and LMU Center for Children With Medical Complexity, Dr. von Hauner Children's Hospital, LMU Hospital, Munich, Germany
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Rapp J, Braun P, Hemmert W, Gleich B. Optimal pulse configuration for peripheral inductive nerve stimulation. Biomed Phys Eng Express 2022; 8. [DOI: 10.1088/2057-1976/ac52d8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 02/08/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Peripheral magnetic stimulation is a promising technique for several applications like rehabilitation or diagnose of neuronal pathways. However, most available magnetic stimulation devices are designed for transcranial stimulation and require high-power, expensive hardware. Modern technology such as rectangular pulses allows to adapt parameters like pulse shape and duration in order to reduce the required energy. Nevertheless, the effect of different temporal electromagnetic field shapes on neuronal structures is not yet fully understood. We created a simulation environment to find out how peripheral nerves are affected by induced magnetic fields and what pulse shapes have the lowest energy requirements. Using the electric field distribution of a Figure-of-8 coil together with an axon model in saline solution, we calculated the potential along the axon and determined the required threshold current to elicit an action potential. Further, for the purpose of selective stimulation, we investigated different axon diameters. Our results show that rectangular pulses have the lowest thresholds at a pulse duration of 20 μs. For sinusoidal coil currents, the optimal pulse duration was found to be 40 μs. Most importantly, with an asymmetric rectangular pulse, the coil current could be reduced from 2.3 kA (cosine shaped pulse) to 600 A. In summary, our results indicate that for magnetic nerve stimulation the use of rectangular pulse shapes holds the potential to reduce the required coil current by a factor of 4, which would be a massive improvement.
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Ruiu E, Valls-Sole J. Excitatory and inhibitory responses to cervical root magnetic stimulation in healthy subjects. Clin Neurophysiol Pract 2021; 6:265-274. [PMID: 34825114 PMCID: PMC8604992 DOI: 10.1016/j.cnp.2021.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/10/2021] [Accepted: 10/09/2021] [Indexed: 12/25/2022] Open
Abstract
We studied excitatory and inhibitory responses to cervical root magnetic stimulation. CRMS elicited direct and reflex responses in hand muscles. CRMS is painless and well tolerated and, therefore, applicable to clinical studies.
Objectives To characterize direct and reflex hand muscle responses to cervical root magnetic stimulation (CRMS) in healthy volunteers during sustained voluntary contraction. Methods In 18 healthy volunteers, we recorded from the first dorsal interosseous (FDI) muscle the responses to CRMS of progressively increasing intensity and level of muscle contraction. The compound muscle action potential (CMAP) and the silent period (SP) were compared to those obtained with plexus, midarm and wrist stimulation. Additionally, in a smaller number of subjects, we obtained the peristimulus time histogram (psth) of single motor unit firing in the FDI, examined the effects of vibration and recorded the modulation of sustained EMG activity in muscles of the lower limbs. Results Increasing CRMS intensity led to larger CMAP with no relevant changes in SP1 or SP2, except for lower amplitude of the burst interrupting the silent period (BISP). Increasing the level of muscle contraction led to reduced CMAP, shorter SP duration and increased BISP amplitude. The psth analysis showed the underlying changes in the motor unit firing frequency that corresponded to the changes seen in the CMAP and the SP with surface recordings. Progressively distal stimulation led to CMAPs of shorter latency and increased amplitude, SPs of longer latency and shorter duration, and a BISP of longer latency. Vibration led to reduction of the SP. CRMS induced SPs in muscles of the lower limb. Conclusions CRMS induces excitatory and inhibitory responses in hand muscles, fitting with the expected behavior of mixed nerve stimulation at very proximal sites. Significance Characterization of the effects of CRMS on hand muscles is of physiological and potentially clinical applicability, as it is a painless and reliable procedure.
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Affiliation(s)
- E Ruiu
- Unit of Clinical Neurology, Department of Clinical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - J Valls-Sole
- IDIBAPS (Institut d'Investigació Biomèdica August Pi i Sunyer), Barcelona 08036, Spain
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Lukanović D, Kunič T, Batkoska M, Matjašič M, Barbič M. Effectiveness of Magnetic Stimulation in the Treatment of Urinary Incontinence: A Systematic Review and Results of Our Study. J Clin Med 2021; 10:jcm10215210. [PMID: 34768730 PMCID: PMC8584787 DOI: 10.3390/jcm10215210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/29/2021] [Accepted: 11/04/2021] [Indexed: 11/16/2022] Open
Abstract
Urinary incontinence (UI) is becoming an increasingly common health problem. UI treatment can be conservative or surgical. This paper focuses on the effectiveness of magnetic stimulation (MS) in the treatment of UI. We performed a systematic review in order to combine and compare results with results from our clinical study. A clinical prospective non-randomized study was carried out at the Ljubljana University Medical Center's Gynecology Division. It included 82 randomly selected female patients, irrespective of their UI type. The success rate of using MS in treating UI was based on standardized ICIQ-UI SF questionnaires. Patients completed 10 therapy sessions on MS, and follow-up was performed 3 months after the last therapy session. UI improved after treatment with MS. The ICIQ-UI SF score improved in patients regardless of the type of UI. However, the greatest decrease in post-treatment assessment ICIQ-UI SF scores was seen in patients with stress urinary incontinence (SUI). Based on the findings described above, it can be concluded that MS is a successful non-invasive conservative method for treating UI. Future studies are necessary, all of which should include a large sample size, a control group, an optimal research protocol, pre-treatment analyses, standardization, and longer follow-ups.
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Affiliation(s)
- David Lukanović
- Department of Gynecology, Division of Gynecology and Obstetrics, Ljubljana University Medical Center, 1000 Ljubljana, Slovenia; (T.K.); (M.B.); (M.B.)
- Correspondence: ; Tel.: +386-1522-6005
| | - Tina Kunič
- Department of Gynecology, Division of Gynecology and Obstetrics, Ljubljana University Medical Center, 1000 Ljubljana, Slovenia; (T.K.); (M.B.); (M.B.)
| | - Marija Batkoska
- Department of Gynecology, Division of Gynecology and Obstetrics, Ljubljana University Medical Center, 1000 Ljubljana, Slovenia; (T.K.); (M.B.); (M.B.)
| | - Miha Matjašič
- Center for Social Informatics, Faculty of Social Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Matija Barbič
- Department of Gynecology, Division of Gynecology and Obstetrics, Ljubljana University Medical Center, 1000 Ljubljana, Slovenia; (T.K.); (M.B.); (M.B.)
- Department of Gynecology and Obstetrics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
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Zschorlich VR, Hillebrecht M, Tanjour T, Qi F, Behrendt F, Kirschstein T, Köhling R. Repetitive Peripheral Magnetic Nerve Stimulation (rPMS) as Adjuvant Therapy Reduces Skeletal Muscle Reflex Activity. Front Neurol 2019; 10:930. [PMID: 31507528 PMCID: PMC6718706 DOI: 10.3389/fneur.2019.00930] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/09/2019] [Indexed: 12/02/2022] Open
Abstract
Background: The reduction of muscle hypertonia and spasticity, as well as an increase in mobility, is an essential prerequisite for the amelioration of physiotherapeutical treatments. Repetitive peripheral magnetic nerve stimulation (rPMS) is a putative adjuvant therapy that improves the mobility of patients, but the underlying mechanism is not entirely clear. Methods: Thirty-eight participants underwent either an rPMS treatment (N = 19) with a 5 Hz stimulation protocol in the posterior tibial nerve or sham stimulation (N = 19). The stimulation took place over 5 min. The study was conducted in a pre-test post-test design with matched groups. Outcome measures were taken at the baseline and after following intervention. Results: The primary outcome was a significant reduction of the reflex activity of the soleus muscle, triggered by a computer-aided tendon-reflex impact. The pre-post differences of the tendon reflex response activity were −23.7% (P < 0.001) for the treatment group. No significant effects showed in the sham stimulation group. Conclusion: Low-frequency magnetic stimulation (5 Hz rPMS) shows a substantial reduction of the tendon reflex amplitude. It seems to be an effective procedure to reduce muscular stiffness, increase mobility, and thus, makes the therapeutic effect of neuro-rehabilitation more effective. For this reason, the 5 Hz rPMS treatment might have the potential to be used as an adjuvant therapy in the rehabilitation of gait and posture control in patients suffering from limited mobility due to spasticity. The effect observed in this study should be investigated conjoined with the presented method in patients with impaired mobility due to spasticity.
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Affiliation(s)
- Volker R Zschorlich
- Faculty of Philosophy, Institute of Sports Science, University of Rostock, Rostock, Germany.,Department of Ageing of Individuals and Society, Faculty of Interdisciplinary Research, University of Rostock, Rostock, Germany
| | - Martin Hillebrecht
- Department of Sport Science, University of Oldenburg, Oldenburg, Germany
| | - Tammam Tanjour
- Faculty of Philosophy, Institute of Sports Science, University of Rostock, Rostock, Germany
| | - Fengxue Qi
- Faculty of Philosophy, Institute of Sports Science, University of Rostock, Rostock, Germany.,Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Technical University Dortmund, Dortmund, Germany.,Department of Sport Training, Sport Coaching College, Beijing Sport University, Bejing, China
| | - Frank Behrendt
- Reha Rheinfelden, Research Department, Rheinfelden, Switzerland
| | - Timo Kirschstein
- Oscar-Langendorff-Institute of Physiology, University Medicine Rostock, Rostock, Germany
| | - Rüdiger Köhling
- Department of Ageing of Individuals and Society, Faculty of Interdisciplinary Research, University of Rostock, Rostock, Germany.,Oscar-Langendorff-Institute of Physiology, University Medicine Rostock, Rostock, Germany
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Ye H, Ng J. Shielding effects of myelin sheath on axolemma depolarization under transverse electric field stimulation. PeerJ 2018; 6:e6020. [PMID: 30533309 PMCID: PMC6282940 DOI: 10.7717/peerj.6020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/29/2018] [Indexed: 01/14/2023] Open
Abstract
Axonal stimulation with electric currents is an effective method for controlling neural activity. An electric field parallel to the axon is widely accepted as the predominant component in the activation of an axon. However, recent studies indicate that the transverse component to the axolemma is also effective in depolarizing the axon. To quantitatively investigate the amount of axolemma polarization induced by a transverse electric field, we computed the transmembrane potential (Vm) for a conductive body that represents an unmyelinated axon (or the bare axon between the myelin sheath in a myelinated axon). We also computed the transmembrane potential of the sheath-covered axonal segment in a myelinated axon. We then systematically analyzed the biophysical factors that affect axonal polarization under transverse electric stimulation for both the bare and sheath-covered axons. Geometrical patterns of polarization of both axon types were dependent on field properties (magnitude and field orientation to the axon). Polarization of both axons was also dependent on their axolemma radii and electrical conductivities. The myelin provided a significant “shielding effect” against the transverse electric fields, preventing excessive axolemma depolarization. Demyelination could allow for prominent axolemma depolarization in the transverse electric field, via a significant increase in myelin conductivity. This shifts the voltage drop of the myelin sheath to the axolemma. Pathological changes at a cellular level should be considered when electric fields are used for the treatment of demyelination diseases. The calculated term for membrane polarization (Vm) could be used to modify the current cable equation that describes axon excitation by an external electric field to account for the activating effects of both parallel and transverse fields surrounding the target axon.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
| | - Jeffrey Ng
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
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Frazer AK, Pearce AJ, Howatson G, Thomas K, Goodall S, Kidgell DJ. Determining the potential sites of neural adaptation to cross-education: implications for the cross-education of muscle strength. Eur J Appl Physiol 2018; 118:1751-1772. [PMID: 29995227 DOI: 10.1007/s00421-018-3937-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/05/2018] [Indexed: 12/11/2022]
Abstract
Cross-education describes the strength gain in the opposite, untrained limb following a unilateral strength training program. Since its discovery in 1894, several studies now confirm the existence of cross-education in contexts that involve voluntary dynamic contractions, eccentric contraction, electrical stimulation, whole-body vibration and, more recently, following mirror feedback training. Although many aspects of cross-education have been established, the mediating neural mechanisms remain unclear. Overall, the findings of this review show that the neural adaptations to cross-education of muscle strength most likely represent a continuum of change within the central nervous system that involves both structural and functional changes within cortical motor and non-motor regions. Such changes are likely to be the result of more subtle changes along the entire neuroaxis which include, increased corticospinal excitability, reduced cortical inhibition, reduced interhemispheric inhibition, changes in voluntary activation and new regions of cortical activation. However, there is a need to widen the breadth of research by employing several neurophysiological techniques (together) to better understand the potential mechanisms mediating cross-education. This fundamental step is required in order to better prescribe targeted and effective guidelines for the clinical practice of cross-education. There is a need to determine whether similar cortical responses also occur in clinical populations where, perhaps, the benefits of cross-education could be best observed.
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Affiliation(s)
- Ashlyn K Frazer
- Department of Physiotherapy, Faculty of Medicine, Nursing and Health Sciences, School of Primary and Allied Health Care, Monash University, PO Box 527, Frankston, Melbourne, VIC, 3199, Australia.
| | - Alan J Pearce
- Discipline of Exercise Science, School of Allied Health, La Trobe University, Melbourne, Australia
| | - Glyn Howatson
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, UK.,Water Research Group, School of Biological Sciences, North West University, Potchefstroom, South Africa
| | - Kevin Thomas
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, UK
| | - Stuart Goodall
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, UK
| | - Dawson J Kidgell
- Department of Physiotherapy, Faculty of Medicine, Nursing and Health Sciences, School of Primary and Allied Health Care, Monash University, PO Box 527, Frankston, Melbourne, VIC, 3199, Australia
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Weintraub MI, Cole SP. Pulsed Magnetic Field Therapy in Refractory Neuropathic Pain Secondary to Peripheral Neuropathy: Electrodiagnostic Parameters—Pilot Study. Neurorehabil Neural Repair 2016; 18:42-6. [PMID: 15035963 DOI: 10.1177/0888439003261024] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Context. Neuropathic pain (NP) from peripheral neuropathy (PN) arises from ectopic firing of unmyelinated C-fibers with accumulation of sodium and calcium channels. Because pulsed electromagnetic fields (PEMF) safely induce extremely low frequency (ELF) quasirectangular currents that can depolarize, repolarize, and hyperpolarize neurons, it was hypothesized that directing this energy into the sole of one foot could potentially modulate neuropathic pain. Objective. To determine if 9 consecutive 1-h treatments in physician’s office (excluding weekends) of a pulsed signal therapy can reduce NP scores in refractory feet with PN. Design/setting/patients. 24 consecutive patients with refractory and symptomatic PN from diabetes, chronic inflammatory demyelinating polyneuropathy (CIDP), pernicious anemia, mercury poisoning, paraneoplastic syndrome, tarsal tunnel, and idiopathic sensory neuropathy were enrolled in this nonplacebo pilot study. The most symptomatic foot received therapy. Primary endpoints were comparison of VAS scores at the end of 9 days and the end of 30 days follow-up compared to baseline pain scores. Additionally, Patients’ Global Impression of Change (PGIC) questionnaire was tabulated describing response to treatment. Subgroup analysis of nerve conduction scores, quantified sensory testing (QST), and serial examination changes were also tabulated. Subgroup classification of pain (Serlin) was utilized to determine if there were disproportionate responses. Intervention. Noninvasive pulsed signal therapy generates a unidirectional quasirectangular waveform with strength about 20 gauss and a frequency about 30 Hz into the soles of the feet for 9 consecutive 1-h treatments (excluding weekends). The most symptomatic foot of each patient was treated. Results. All 24 feet completed 9 days of treatment. 15/24 completed follow-up (62%) with mean pain scores decreasing 21% from baseline to end of treatment (P = 0.19) but with 49% reduction of pain scores from baseline to end of follow-up (P < 0.01). Of this group, self-reported PGIC was improved 67% (n = 10) and no change was 33% (n = 5). An intent-to-treat analysis based on all 24 feet demonstrated a 19% reduction in pain scores from baseline to end of treatment (P = 0.10) and a 37% decrease from baseline to end of follow-up ( P < 0.01). Subgroup analysis revealed 5 patients with mild pain with nonsignificant reduction at end of follow-up. Of the 19 feet with moderate to severe pain, there was a 28% reduction from baseline to end of treatment (P < 0.05) and a 39% decrease from baseline to end of follow-up (P < 0.01). Benefit was better in those patients with axonal changes and advanced CPT baseline scores. The clinical examination did not change. There were no adverse events or safety issues. Conclusions. These pilot data demonstrate that directing PEMF to refractory feet can provide unexpected shortterm analgesic effects in more than 50% of individuals. The role of placebo is not known and was not tested. The precise mechanism is unclear yet suggests that severe and advanced cases are more magnetically sensitive. Future studies are needed with randomized placebo-controlled design and longer treatment periods.
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Affiliation(s)
- Shaheen Khazali
- St. Mary's maternity; Secretary to Mr TC Hillard; St. Mary's road Poole UK BH15 2LG
| | - Simon Jackson
- John Radcliffe Hospital; Room 4146 - Women's Centre; Oxford UK OX3 9DU
| | - James Balmforth
- Royal Bournemouth Hospital NHS Trust; Castle Lane East Bournemouth Dorset UK BH7 7DW
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Tamè L, Holmes NP. Involvement of human primary somatosensory cortex in vibrotactile detection depends on task demand. Neuroimage 2016; 138:184-196. [PMID: 27233148 DOI: 10.1016/j.neuroimage.2016.05.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/09/2016] [Accepted: 05/22/2016] [Indexed: 10/21/2022] Open
Abstract
UNLABELLED Detecting and discriminating sensory stimuli are fundamental functions of the nervous system. Electrophysiological and lesion studies suggest that macaque primary somatosensory cortex (SI) is critically involved in discriminating between stimuli, but is not required simply for detecting stimuli. By contrast, transcranial magnetic stimulation (TMS) studies in humans have shown near-complete disruption of somatosensory detection when a single pulse of TMS is delivered over SI. To address this discrepancy, we measured the sensitivity and decision criteria of participants detecting vibrotactile stimuli with individually-tailored fMRI-guided TMS over SI, over a control site not activated by vibrotactile stimuli (inferior parietal lobule, IPL), or away from the head (a no TMS condition). In a one-interval detection task, TMS increased participants' likelihood of reporting 'no' target present regardless of site, but TMS over SI also decreased detection sensitivity, and prevented improvement in tactile sensitivity over time. We then measured tactile thresholds in a series of two-interval forced-choice (2IFC) detection and discrimination tasks with lower dependence on response criteria and short-term memory load. We found that thresholds for detecting stimuli were comparable with TMS over SI and IPL, but TMS over SI specifically and significantly impaired frequency discrimination. We conclude that, in accordance with macaque studies, human SI is required for discriminating between tactile stimuli and for maintaining stimulus representations over time, or under high task demand, but may not be required for simple tactile detection. SIGNIFICANT STATEMENT Studies on monkeys have suggested that the primary somatosensory cortex is responsible for discriminating between different vibrations on the fingertips, but not just for detecting these vibrations. However, similar studies in humans suggest that the somatosensory cortex is required both for detecting and discriminating between tactile stimuli. We used magnetic brain stimulation to interfere with human somatosensory cortex while healthy volunteers detected and discriminated between vibrations applied to their fingertips. We found that the somatosensory cortex is required for keeping vibrotactile stimuli in memory for short periods of time and for comparing two vibrotactile stimuli, but is not required merely for detecting vibrotactile stimulation. This suggests that human primary somatosensory cortex is not always needed for vibrotactile detection.
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Affiliation(s)
- Luigi Tamè
- Centre for Integrative Neuroscience & Neurodynamics, School of Psychology & Clinical Language Sciences, University of Reading, Reading, UK; Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy; Department of Psychological Sciences, Birkbeck, University of London, London, UK.
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Repetitive peripheral magnetic stimulation to reduce pain or improve sensorimotor impairments: A literature review on parameters of application and afferents recruitment. Neurophysiol Clin 2015; 45:223-37. [DOI: 10.1016/j.neucli.2015.08.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 08/06/2015] [Accepted: 08/06/2015] [Indexed: 11/22/2022] Open
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Veltsista D, Chroni E. Usefulness of cervical root magnetic stimulation in assessing proximal motor nerve conduction. J Electromyogr Kinesiol 2015. [PMID: 26216867 DOI: 10.1016/j.jelekin.2015.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVES To evaluate the reliability and utility of cervical root magnetic stimulation in exploring proximal motor conduction. METHODS In 20 patients with demyelinating polyneuropathy (DPN), 20 patients with amyotrophic lateral sclerosis (ALS) and 25 healthy subjects, evoked compound muscle action potentials (CMAPs) were recorded from abductor digiti minimi muscle in response to electrical stimulation up to Erb's point and magnetic stimulation up to the cervical roots. RESULTS In all healthy and ALS subjects, magnetic root stimulation confirmed the absence of conduction abnormalities, including those in whom supramaximal responses at Erb's point were not achieved. In the DPN group, conduction block and/or temporal dispersion was revealed by magnetic root stimulation in 9 out of 20 patients (45%), 3 more than those detected at Erb's point. CONCLUSIONS Cervical root stimulation allowed clear distinction between motor neuronopathy and DPN. It is recommended as part of the routine evaluation of patients suspected of having DPN, especially when distal nerve studies are inconclusive.
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Affiliation(s)
- Dimitra Veltsista
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece.
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Gallasch E, Christova M, Kunz A, Rafolt D, Golaszewski S. Modulation of sensorimotor cortex by repetitive peripheral magnetic stimulation. Front Hum Neurosci 2015; 9:407. [PMID: 26236220 PMCID: PMC4500907 DOI: 10.3389/fnhum.2015.00407] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/01/2015] [Indexed: 11/13/2022] Open
Abstract
This study examines with transcranial magnetic stimulation (TMS) and with functional magnetic resonance imaging (fMRI) whether 20 min of repetitive peripheral magnetic stimulation (rPMS) has a facilitating effect on associated motor controlling regions. Trains of rPMS with a stimulus intensity of 150% of the motor threshold (MT) were applied over right hand flexor muscles of healthy volunteers. First, with TMS, 10 vs. 25 Hz rPMS was examined and compared to a control group. Single and paired pulse motor evoked potentials (MEPs) from flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles were recorded at baseline (T0), post rPMS (T1), 30 min post (T2), 1 h post (T3) and 2 h post rPMS (T4). Then, with fMRI, 25 Hz rPMS was compared to sham stimulation by utilizing a finger tapping activation paradigm. Changes in bloodoxygen level dependent (BOLD) contrast were examined at baseline (PRE), post rPMS (POST1) and 1 h post rPMS (POST2). With TMS facilitation was observed in the target muscle (FCR) following 25 Hz rPMS: MEP recruitment curves (RCs) were increased at T1, T2 and T3, and intracortical facilitation (ICF) was increased at T1 and T2. No effects were observed following 10 Hz rPMS. With fMRI the BOLD contrast at the left sensorimotor area was increased at POST1. Compared to inductions protocols based on transcutaneous electrical stimulation and mechanical stimulation, the rPMS induced effects appeared shorter lasting.
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Affiliation(s)
- Eugen Gallasch
- Department of Physiology, Medical University of Graz Graz, Austria
| | - Monica Christova
- Department of Physiology, Medical University of Graz Graz, Austria ; Institute of Physiotherapy, University of Applied Sciences FH-Joanneum Graz, Austria
| | - Alexander Kunz
- Department of Neurology, Paracelsus Medical University of Salzburg Salzburg, Austria
| | - Dietmar Rafolt
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna Vienna, Austria
| | - Stefan Golaszewski
- Department of Neurology, Paracelsus Medical University of Salzburg Salzburg, Austria
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Beaulieu LD, Massé-Alarie H, Brouwer B, Schneider C. Noninvasive neurostimulation in chronic stroke: a double-blind randomized sham-controlled testing of clinical and corticomotor effects. Top Stroke Rehabil 2015; 22:8-17. [PMID: 25776116 DOI: 10.1179/1074935714z.0000000032] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Repetitive peripheral magnetic stimulation (RPMS) is a painless and noninvasive method to produce afferents via the depolarization of the peripheral nervous system. A few studies tested RPMS after-effects on cerebral plasticity and motor recovery in stroke individuals, but evidences remain limited. OBJECTIVES This study aimed to explore whether RPMS could mediate improvements in corticomotor and clinical outcomes associated with ankle impairments in chronic stroke. METHODS Eighteen subjects with chronic stroke were randomly allocated to RPMS or sham group and compared to 14 healthy subjects. Stimulation was applied over the paretic tibialis anterior (TA). Ankle impairments on the paretic side and ipsilesional TA cortical motor representation were tested clinically and by transcranial magnetic stimulation (TMS), respectively. RESULTS In the RPMS group, ankle dorsiflexion mobility and maximal isometric strength increased and resistance to plantar flexor stretch decreased. The magnitude of change seemed to be related to cortical and corticospinal integrity. Sham stimulation yielded no effect. Changes in TMS outcome and their relationships with clinical improvements were limited. CONCLUSIONS RPMS improved ankle impairments in chronic stroke likely by a dynamic influence of sensory inputs on synaptic plasticity. The neurophysiological mechanisms potentially underlying the clinical effects are unclear. More studies are warranted to test the spinal and hemispheric changes responsible for the clinical improvements with emphasis on circuits spared by the lesion.
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Aydoğmus S, Keskin HL, Aydoğmus H, Celen E, Ackay GY, Sivaslioğlu AA, Avşar AF. Can Extracorporeal Magnetic Innervation Be a Treatment Modality for Primary Dysmenorrhea. Gynecol Obstet Invest 2014; 77:250-4. [DOI: 10.1159/000360906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/26/2014] [Indexed: 11/19/2022]
Abstract
<b><i>Background/Aims:</i></b> To evaluate the efficacy of extracorporeal magnetic innervation (ExMI) as a treatment for primary dysmenorrhea compared with nonsteroidal anti-inflammatory drugs (NSAIDs) and combined oral contraceptives (COCs). <b><i>Methods:</i></b> The cases were randomized into three groups (NSAID = 51, ExMI = 53, COC = 54). ExMI was applied for a total of 10 sessions. Women in the NSAID group used an oral NSAID at the start of each menstruation. Women in the COC group were given combined pills. Of the treatment options, ExMI was applied for only a single period, whereas NSAID and COC use continued for 12 months. <b><i>Results:</i></b> At the first menstruation, visual analog scale (VAS) scores improved significantly in all groups (p < 0.001). NSAIDs and COCs continued to show efficacy over the entire study period (p < 0.05). However, in the ExMI group, VAS values increased from the first menstruation until 12 months. The VAS score at the 12th month was significantly higher in the ExMI group than in the other groups (p < 0.05), but markedly lower than the pretreatment value (49.9 ± 8.3 vs. 71.1 ± 10.1, p < 0.001). <b><i>Conclusions:</i></b> ExMI therapy might be a promising novel noninvasive option for primary dysmenorrhea. Efficacy began to decline after 3 months, but continued for 12 months.
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Matsumoto H, Hanajima R, Terao Y, Ugawa Y. Magnetic-motor-root stimulation: Review. Clin Neurophysiol 2013; 124:1055-67. [DOI: 10.1016/j.clinph.2012.12.049] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/18/2012] [Accepted: 12/28/2012] [Indexed: 12/13/2022]
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18
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Kizilay F, Bilgen R, Aydin Gungor H, Uysal H, Ertekin C. Flexor reflexes elicited by magnetic and electric stimulation of the sural nerve. Neurol Res 2011; 33:609-13. [DOI: 10.1179/1743132810y.0000000026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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19
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Assessment of motor pathways by magnetic stimulation in human and veterinary medicine. Vet J 2011; 187:174-81. [DOI: 10.1016/j.tvjl.2009.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 12/09/2009] [Accepted: 12/11/2009] [Indexed: 11/22/2022]
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20
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The use of extracorporeal magnetic innervation for the treatment of stress urinary incontinence in older women: a pilot study. Arch Gynecol Obstet 2010; 284:1163-8. [PMID: 21184090 DOI: 10.1007/s00404-010-1814-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022]
Abstract
PURPOSE Stress urinary incontinence (SUI) is a major health problem that has substantial and important effects on health-related quality of life. In recent years, extracorporeal magnetic innervation (ExMI) has become a preferred method of treatment in urinary incontinence. This study presents the effects of ExMI treatment on pelvic floor muscle strength, urinary symptoms, incontinence conditions and quality of life of older women with SUI. METHODS A total of 13 patients between the ages of 61 and 69 (mean 65.23 ± 2.8 years) were treated for SUI with ExMI. The following parameters were investigated: urinary symptoms, pelvic floor electromyographic (EMG) activity, 1-h pad test, incontinence conditions utilizing visual analog scale (VAS) and quality of life using Turkish version of the Urogenital Distress Inventory (UDI-6) and the Incontinence Quality of Life Instrument (I-QoL). All assessments were conducted at baseline and at the end of the study. Treatment lasted for 20 min, twice a week and for a total of 6 weeks. RESULTS The urinary symptoms and incontinence conditions decreased after the ExMI treatment sessions. The pad test results indicated a reduction in urine loss (p = 0.016). EMG values were improved (p = 0.005). Scores of I-QoL, UDI-6 and VAS were reduced after the treatment, respectively (p = 0.002), (p = 0.002) and (p = 0.006). CONCLUSION Extracorporeal magnetic innervation can be considered as it is an alternative, non-invasive and painless treatment method with good compliance for treatment of SUI in older patients.
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Ye H, Cotic M, Fehlings MG, Carlen PL. Transmembrane potential generated by a magnetically induced transverse electric field in a cylindrical axonal model. Med Biol Eng Comput 2010; 49:107-19. [PMID: 21063912 DOI: 10.1007/s11517-010-0704-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 10/21/2010] [Indexed: 11/26/2022]
Abstract
During the electrical stimulation of a uniform, long, and straight nerve axon, the electric field oriented parallel to the axon has been widely accepted as the major field component that activates the axon. Recent experimental evidence has shown that the electric field oriented transverse to the axon is also sufficient to activate the axon, by inducing a transmembrane potential within the axon. The transverse field can be generated by a time-varying magnetic field via electromagnetic induction. The aim of this study was to investigate the factors that influence the transmembrane potential induced by a transverse field during magnetic stimulation. Using an unmyelinated axon model, we have provided an analytic expression for the transmembrane potential under spatially uniform, time-varying magnetic stimulation. Polarization of the axon was dependent on the properties of the magnetic field (i.e., orientation to the axon, magnitude, and frequency). Polarization of the axon was also dependent on its own geometrical (i.e., radius of the axon and thickness of the membrane) and electrical properties (i.e., conductivities and dielectric permittivities). Therefore, this article provides evidence that aside from optimal coil design, tissue properties may also play an important role in determining the efficacy of axonal activation under magnetic stimulation. The mathematical basis of this conclusion was discussed. The analytic solution can potentially be used to modify the activation function in current cable equations describing magnetic stimulation.
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Affiliation(s)
- Hui Ye
- Toronto Western Research Institute, University Health Network, Toronto, ON, Canada.
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22
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Recoskie BJ, Scholl TJ, Chronik BA. The discrepancy between human peripheral nerve chronaxie times as measured using magnetic and electric field stimuli: the relevance to MRI gradient coil safety. Phys Med Biol 2009; 54:5965-79. [DOI: 10.1088/0031-9155/54/19/020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Asymmetry of magnetic motor evoked potentials recorded in calf muscles of the dominant and non-dominant lower extremity. Neurosci Lett 2009; 459:74-8. [DOI: 10.1016/j.neulet.2009.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 04/27/2009] [Accepted: 05/01/2009] [Indexed: 11/29/2022]
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Abstract
Weakness of the limbs and respiratory muscles has increasingly been found to be a frequent event that complicates the medical history of patients in Intensive Care. The problem normally affects more serious cases and presents as muscular weakness leading to flaccid paralysis and difficulty in weaning patients off mechanical ventilation. This latter sign leads the intensivist to suspect possible involvement of the neuromuscular respiratory system. Unfortunately, in-depth clinical assessment of the neuromuscular respiratory system is difficult with critically ill patients, and electrophysiological studies have been used instead to overcome this problem. Of these latter, electric and electromagnetic stimulation of the phrenic nerve have been successful (along with needle electromyography of the diaphragm) in identifying the causes of neuromuscular respiratory insufficiency, especially in Intensive Care. In this brief chapter, we will be discussing the technique of electric stimulation of the phrenic nerve and neuromuscular respiratory insufficiency within the field of critical illness polyneuropathy.
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25
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Miller KC, Knight KL. Pain and soreness associated with a percutaneous electrical stimulation muscle cramping protocol. Muscle Nerve 2008; 36:711-4. [PMID: 17654560 DOI: 10.1002/mus.20857] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Muscle cramps are difficult to study scientifically because of their spontaneity and unpredictability. Various laboratory techniques to induce muscle cramps have been explored but the best technique for inducing cramps is unclear. Electrical stimulation appears to be the most reliable, but there is a perception that it is extremely painful. Data to support this perception are lacking. We hypothesized that electrical stimulation is a tolerable method of inducing cramps with few side effects. We measured cramp frequency (HZ), pain during electrical stimulation, and soreness before, at 5 s, and 30, 60, and 90 min after cramp induction using a 100-mm visual analog scale. Group 1 received tibial nerve stimulation on 5 consecutive days; Group 2 received it on alternate days for five total treatments. Pain and soreness were mild. The highest ratings occurred on Day 1 and decreased thereafter. Intersession reliability was high. Our study showed that electrical stimulation causes little pain or soreness and is a reliable method for inducing cramps.
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Affiliation(s)
- Kevin C Miller
- Human Performance Research Center, Brigham Young University, 106 Smith Fieldhouse, Provo, Utah 84602, USA.
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Khazali S, Jackson S, Balmforth J. Electromagnetic treatment for urinary incontinence in adults. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2007. [DOI: 10.1002/14651858.cd006711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Shimada Y, Sakuraba T, Matsunaga T, Misawa A, Kawatani M, Itoi E. Effects of therapeutic magnetic stimulation on acute muscle atrophy in rats after hindlimb suspension. Biomed Res 2006; 27:23-7. [PMID: 16543662 DOI: 10.2220/biomedres.27.23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In most subjects with spinal cord injury, the spinal neurons below the level of injury are spared. Therefore, it is conceivable that the skeletal muscles innervated by these spinal nerves can be activated by applying therapeutic magnetic stimulation along the dorsal spine. The purpose of this study was to evaluate the ability of magnetic stimulation to prevent acute muscle atrophy in rats after hindlimb suspension. Forty adult male Wistar rats were randomly assigned to stimulated and non-stimulated (control) groups. Their hindlimbs were unweighted using a suspension method, causing muscle atrophy. In the stimulation group, magnetic stimulation (20 Hz, 60 min per day) was applied to the sciatic nerve for 10 days. After the stimulation period, the tibialis anterior (TA) and extensor digitorum longus (EDL) were surgically removed and histologically measured. The lesser diameters of type 1, 2A, and 2B muscle fibers were significantly greater in the stimulated group than in the non-stimulated group for both the TA and EDL (p < 0.05). The mean difference in lesser fiber diameter was 20% (range, 14%-27%). These results suggest that therapeutic magnetic stimulation is an effective method of preventing muscle atrophy.
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Affiliation(s)
- Yoichi Shimada
- Rehabilitation Division, Akita University School of Medicine, Akita, Japan.
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Kim JS, Yoon H, Chung WS, Shim BS. The Long Term Effect of Extracorporeal Magnetic Innervation Therapy with Pelvic Floor Muscle Exercise for Stress Urinary Incontinence. Korean J Urol 2006. [DOI: 10.4111/kju.2006.47.12.1334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Jae Sik Kim
- Department of Urology, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Hana Yoon
- Department of Urology, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Woo Sik Chung
- Department of Urology, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Bong Suk Shim
- Department of Urology, College of Medicine, Ewha Womans University, Seoul, Korea
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Zhou Yi Syuu W, Hsiao I, Lin VWH, Longhurst JC. Modulation of cardiovascular excitatory responses in rats by transcutaneous magnetic stimulation: role of the spinal cord. J Appl Physiol (1985) 2005; 100:926-32. [PMID: 16269522 DOI: 10.1152/japplphysiol.01130.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study investigated the efficacy of magnetic stimulation on the reflex cardiovascular responses induced by gastric distension in anesthetized rats and compared these responses to those influenced by electroacupuncture (EA). Unilateral magnetic stimulation (30% intensity, 2 Hz) at the Jianshi-Neiguan acupoints (pericardial meridian, P 5-6) overlying the median nerve on the forelimb for 24 min significantly decreased the reflex pressor response by 32%. This effect was noticeable by 20 min of magnetic stimulation and continued for 24 min. Median nerve denervation abolished the inhibitory effect of magnetic stimulation, indicating the importance of somatic afferent input. Unilateral EA (0.3-0.5 mA, 2 Hz) at P 5-6 using similar durations of stimulation similarly inhibited the response (35%). The inhibitory effects of EA occurred earlier and were marginally longer (20 min) than magnetic stimulation. Magnetic stimulation at Guangming-Xuanzhong acupoints (gallbladder meridian, GB 37-39) overlying the superficial peroneal nerve on the hindlimb did not attenuate the reflex. Intravenous naloxone immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex, suggesting involvement of the opioid system. Also, intrathecal injection of delta- and kappa-opioid receptors antagonists, ICI174,864 (n=7) and nor-binaltorphimine (n=6) immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex. In contrast, the mu-opioid antagonist CTOP (n=7) failed to alter the cardiovascular reflex. The endogenous neurotransmitters for delta- and kappa-opioid receptors, enkephalins and dynorphin but not beta-endorphin, therefore appear to play significant roles in the spinal cord in mediating magnetic stimulation-induced modulation of cardiovascular reflex responses.
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MESH Headings
- Afferent Pathways/physiology
- Animals
- Blood Pressure/physiology
- Cardiovascular Physiological Phenomena
- Cardiovascular System/drug effects
- Cardiovascular System/innervation
- Electroacupuncture
- Enkephalin, Leucine/analogs & derivatives
- Enkephalin, Leucine/pharmacology
- Magnetics
- Male
- Median Nerve/physiology
- Naloxone/pharmacology
- Neurotransmitter Agents/physiology
- Opioid Peptides/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, delta/analysis
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/physiology
- Receptors, Opioid, kappa/analysis
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/physiology
- Receptors, Opioid, mu/analysis
- Receptors, Opioid, mu/physiology
- Reflex/drug effects
- Reflex/physiology
- Spinal Cord/chemistry
- Spinal Cord/physiology
- Stomach/physiology
- Sympathetic Nervous System/drug effects
- Sympathetic Nervous System/physiology
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Affiliation(s)
- Wei Zhou Yi Syuu
- Department of Medicine, Medical Science 1 C240, College of Medicine, Univ. of California, Irvine, CA 92697-4075, USA.
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Winemiller MH, Billow RG, Laskowski ER, Harmsen WS. Effect of magnetic vs sham-magnetic insoles on nonspecific foot pain in the workplace: a randomized, double-blind, placebo-controlled trial. Mayo Clin Proc 2005; 80:1138-45. [PMID: 16178493 DOI: 10.4065/80.9.1138] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To determine whether magnetic insoles are effective for relieving nonspecific subjective foot pain in the workplace, resulting in improved job satisfaction. SUBJECTS AND METHODS A prospective, randomized, double-blind, placebo-controlled study of health care employees who experienced nonspecific foot pain for at least 30 days, which occurred more days than not, was conducted between February 2001 and January 2002 at the Mayo Clinic in Rochester, Minn. Participants were asked to wear either magnetic or sham-magnetic cushioned insoles for at least 4 hours daily, 4 days per week for 8 weeks. The primary outcome variable was reported foot pain (by categorical response of change from baseline and by visual analog scale) at 4 and 8 weeks. Secondary outcome variables included graded intensity of pain experienced during various daily activities and the effect of insoles on job performance and enjoyment. RESULTS Among 89 enrolled participants, 6 either withdrew before wearing insoles or were noncompliant with follow-up questionnaires; 83 participants remained for full statistical analysis. Participants in both treatment groups reported improvements in foot pain during the study period. No significant differences in categorical response to pain or pain intensity were seen with use of magnetic vs sham-magnetic insoles. CONCLUSIONS The magnetic insoles used in this study by a heterogeneous population with chronic nonspecific foot pain were not clinically effective. Findings confirmed that nonspecific foot pain significantly interferes with some employees' ability to enjoy their jobs and that treatment of that pain improves job satisfaction.
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Affiliation(s)
- Mark H Winemiller
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Kim JW, Kim MJ, Noh JY, Lee HY, Han SW. Extracorporeal pelvic floor magnetic stimulation in children with voiding dysfunction. BJU Int 2005; 95:1310-3. [PMID: 15892823 DOI: 10.1111/j.1464-410x.2005.05524.x] [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] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To determine the effect of extracorporeal pelvic floor magnetic stimulation in children with an overactive bladder, as although such stimulation is an effective treatment for voiding dysfunction such as urge incontinence (UI) and urgency-frequency syndrome, experience in children is scarce. PATIENTS AND METHODS This prospective study included 42 children diagnosed with an overactive bladder, based on urodynamic or video-urodynamic study; a complete follow-up was available in 34. The children were grouped into those with UI only, not monosymptomatic nocturnal enuresis (nMNE), or MNE, according to their symptoms. Clinical variables were assessed by recording a voiding and nocturnal enuresis diary before and after magnetic stimulation, the latter being administered twice a week for 4 weeks using a size-adjusted magnetic chair (each session took 20 min). RESULTS The UI only and nMNE group had a significant decrease in voiding frequency and frequency of UI (P < 0.05); the MNE group also had a significant decrease in voiding frequency (P < 0.05). There was a significant increase in functional bladder capacity in all groups (P < 0.05) but no significant decrease in the mean volume and frequency of NE in the nMNE and MNE groups (P > 0.05). CONCLUSIONS Extracorporeal pelvic floor magnetic stimulation has an acute effect on voiding dysfunction such as urge syndrome in children. However, controlled studies with a sham-stimulation group and various durations of stimulation are necessary for its application as a primary treatment for voiding dysfunction in children.
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Affiliation(s)
- Jae Wook Kim
- Brain Korea 21 Project for Medical Science, Urological Science Institute, Yonsei University College Of Medicine, Seoul, Korea
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Yokoyama T, Fujita O, Nishiguchi J, Nozaki K, Nose H, Inoue M, Ozawa H, Kumon H. Extracorporeal magnetic innervation treatment for urinary incontinence. Int J Urol 2005; 11:602-6. [PMID: 15285749 DOI: 10.1111/j.1442-2042.2004.00857.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Extracorporeal magnetic innervation (ExMI) is a new technology used for pelvic muscle strengthening for the treatment of stress urinary incontinence. We explored whether this new technology is effective for patients with urge incontinence, as well as those with stress urinary incontinence. METHODS We studied 20 patients with urge incontinence and 17 patients with stress urinary incontinence. The Neocontrol system (Neotonus Inc., Marietta, GA) was used. Treatment sessions were for 20 min, twice a week for 8 weeks. Evaluations were performed by bladder diaries, one-hour pad weight testing, quality-of-life surveys and urodynamic studies. RESULTS Of the urge incontinence cases, five patients were cured (25.0%), 12 patients improved (60.0%) and three patients did not show any improvement (15.0%). Leak episodes per day reduced from 5.6 times to 1.9 times at 8 weeks (P < 0.05). Eight patients with urge incontinence recurred within 24 weeks after the last treatment (47.1%). Of the stress incontinence cases, nine patients were cured (52.9%), seven patients improved (41.1%) and one patient did not show any improvement (6%). In one-hour pad weight testing, the mean pad weight reduced from 7.9 g to 1.9 g at 8 weeks (P < 0.05). Three patients returned to the baseline values within 24 weeks after the last treatment (17.6%). No side-effects were experienced by any of the patients. CONCLUSION Although the results for urge incontinence were less effective than for stress urinary incontinence, ExMI therapy offers a new option for urge incontinence as well as stress urinary incontinence.
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Affiliation(s)
- Teruhiko Yokoyama
- Department of Urology, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan.
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Bradshaw HD, Barker AT, Radley SC, Chapple CR. The acute effect of magnetic stimulation of the pelvic floor on involuntary detrusor activity during natural filling and overactive bladder symptoms. BJU Int 2003; 91:810-3. [PMID: 12780838 DOI: 10.1046/j.1464-410x.2003.04235.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the effect of magnetic stimulation of the pelvic floor (MSPF) on involuntary detrusor activity observed during natural filling, and on the overactive bladder symptom complex. PATIENTS AND METHODS Eighteen women with detrusor overactivity on conventional cystometry underwent ambulatory urodynamic monitoring over two filling cycles. Fluid intake was standardized, provocative manoeuvres applied at regular intervals and symptoms documented contemporaneously. During the second filling cycle MSPF was delivered whenever the detrusor pressure increased by > 5 cmH2O. The women were subsequently treated with MSPF for 6 weeks; their lower urinary tract symptoms were assessed before and after treatment. RESULTS Comparing the second (stimulated) cycle with the first (unstimulated) cycle, cystometric capacity was higher (373 vs 224 mL, P < 0.03). and involuntary detrusor activity of shorter duration (370 vs 427 s, P < 0.82) and lower amplitude (53 vs 63 cmH2O, P < or = 0.05). All women tolerated the procedure comfortably, but nine found it too time-consuming and withdrew. In the nine women who completed treatment there was no consistent change in overactive bladder symptoms. CONCLUSIONS In this pilot study, MSPF during natural filling was associated with a decrease in the amplitude of involuntary detrusor contractions and a significant increase in cystometric capacity. However, MSPF had a variable effect on sensations of urgency, both acutely and after treatment, and currently there is no evidence to suggest that MSPF has an enduring effect on symptoms of the overactive bladder.
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Affiliation(s)
- H D Bradshaw
- Department of Urology, Sheffield Teaching Hospitals, UK.
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Misawa T, Kiyono Y, Nakatsuchi Y, Shindo M, Takaoka K. Diagnosis of thoracic outlet syndrome by magnetic stimulation of the brachial plexus. J Orthop Sci 2002; 7:167-71. [PMID: 11956975 DOI: 10.1007/s007760200029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The abductor pollicis brevis (APB) and abductor digiti minimi (ADM) compound muscle action potential (CMAP) latencies, and median and ulnar motor conduction velocities (MCVs), obtained by magnetic stimulation of the brachial plexus, were evaluated for the diagnosis of thoracic outlet syndrome (TOS). These measurements were compared in three groups of limbs: (1) the symptomatic limbs of patients with TOS (symptomatic group), (2) the asymptomatic con-tralateral limbs of these patients (asymptomatic group), and (3) the limbs of healthy control subjects (control group). Although no significant differences were observed in MCVs among the three groups, the APB CMAP latency in the sym-ptomatic group (12.0 +/- 1.2 ms) was significantly prolonged compared with that in the control group (10.4 +/- 0.64 ms; P < 0.01), and the ADM CMAP latency in the symptomatic group (11.0 +/- 0.82 ms) was also significantly prolonged compared with that in the control group (10.1 +/- 0.59 ms; P < 0.01). The possibility is suggested that the evaluation of APB and ADM CMAP latencies by magnetic stimulation of the brachial plexus may be helpful for the diagnosis of TOS.
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Affiliation(s)
- Tomoko Misawa
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-0802, Japan
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Schnabel V, Struijk JJ. Calculation of electric fields in a multiple cylindrical volume conductor induced by magnetic coils. IEEE Trans Biomed Eng 2001; 48:78-86. [PMID: 11235594 DOI: 10.1109/10.900251] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A method is presented for calculating the electric field, that is induced in a cylindrical volume conductor by an alternating electrical current through a magnetic coil of arbitrary shape and position. The volume conductor is modeled as a set of concentric, infinitely long, homogeneous cylinders embedded in an outer space that extends to infinity. An analytic expression of the primary electric field induced by the magnetic coil, assuming quasi-static conditions, is combined with the analytic solution of the induced electric scalar potential due to the inhomogeneities of the volume conductor at the cylindrical interfaces. The latter is obtained by the method of separation of variables based on expansion with modified Bessel functions. Numerical results are presented for the case of two cylinders representing a nerve bundle with perineurium. An active cable model of a myelinated nerve fiber is included, and the effect of the nerve fiber's undulation is shown.
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Affiliation(s)
- V Schnabel
- Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajers Vej 7 D3, DK-9220 Aalborg, Denmark.
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Yamanishi T, Sakakibara R, Uchiyama T, Suda S, Hattori T, Ito H, Yasuda K. Comparative study of the effects of magnetic versus electrical stimulation on inhibition of detrusor overactivity. Urology 2000; 56:777-81. [PMID: 11068300 DOI: 10.1016/s0090-4295(00)00779-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To perform a randomized comparative study investigating the urodynamic effects of functional magnetic stimulation (FMS) and functional electrical stimulation (FES) on the inhibition of detrusor overactivity. METHODS Thirty-two patients with urinary incontinence due to detrusor overactivity (15 men, 17 women; age 62. 3 +/- 16.6 years) were randomly assigned to two treatment groups (15 patients in the FMS group and 17 in the FES group). Stimulation was applied continuously at 10 Hz in both groups. For FMS, the magnetic stimulator unit was set on an armchair type seat and had a concave-shaped coil, so that the patients could sit during stimulation. For FES, a vaginal electrode was used in the women and a surface electrode on the dorsal part of the penis was used in the men. Cystometry was performed before and during the stimulation. RESULTS The bladder capacity at the first desire to void and the maximum cystometric capacity increased significantly during stimulation compared with prestimulation levels in both groups (P = 0.0054 and 0.0026, respectively, in the FMS group and P = 0.0015 and 0.0229, respectively, in the FES group). However, the increase in the maximum cystometric capacity was significantly (P = 0.0135) greater in the FMS group (114.2 +/- 124.1 mL or an increase of 105. 5% +/- 130.4% compared with the pretreatment level) than that in the FES group (32.3 +/- 56.6 mL or an increase of 16.3% +/- 33.9%). Detrusor overactivity was abolished in 3 patients in the FMS group but not in any patient in the FES group. CONCLUSIONS Although both treatments were effective, the inhibition of detrusor overactivity appeared greater in the FMS group than in the FES group.
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Affiliation(s)
- T Yamanishi
- Department of Urology, Chiba University School of Medicine, Chiba, Japan
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YAMANISHI TOMONORI, YASUDA KOSAKU, SUDA SHIN, ISHIKAWA NORIO, SAKAKIBARA RYUJI, HATTORI TAKAMICHI. EFFECT OF FUNCTIONAL CONTINUOUS MAGNETIC STIMULATION FOR URINARY INCONTINENCE. J Urol 2000. [DOI: 10.1016/s0022-5347(05)67899-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- TOMONORI YAMANISHI
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
| | - KOSAKU YASUDA
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
| | - SHIN SUDA
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
| | - NORIO ISHIKAWA
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
| | - RYUJI SAKAKIBARA
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
| | - TAKAMICHI HATTORI
- From the Departments of Urology and Neurology, Chiba University, School of Medicine, Chiba and the Department of Urology, Dokkyo University, Medical School, Koshigaya Hospital, Saitama, Japan
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Trock DH. Electromagnetic fields and magnets. Investigational treatment for musculoskeletal disorders. Rheum Dis Clin North Am 2000; 26:51-62, viii. [PMID: 10680193 DOI: 10.1016/s0889-857x(05)70119-8] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Certain pulsed electromagnetic fields (PEMF) affect the growth of bone and cartilage in vitro, with potential application as an arthritis treatment. PEMF stimulation is already a proven remedy for delayed fractures, with potential clinical application for osteoarthritis, osteonecrosis of bone, osteoporosis, and wound healing. Static magnets may provide temporary pain relief under certain circumstances. In both cases, the available data is limited. The mechanisms underlying the use of PEMF and magnets are discussed.
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Affiliation(s)
- D H Trock
- Yale University School of Medicine, New Haven, Connecticut, USA
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Abstract
The lack of a practical model has hampered attempts to study the pathophysiology of muscle cramps. We investigated the feasibility, efficacy, and reproducibility of repetitive magnetic stimulation in producing experimental cramps. In 14 healthy subjects, the tibial nerve at the ankle was stimulated with a magnetic stimulator at rates beginning at 4 Hz to a maximum of 20 Hz. The frequency was gradually increased until a cramp was produced. Ten of 14 subjects demonstrated a muscle cramp. All subjects rated the discomfort of the procedure to be mild or moderate. Repeat testing yielded values that were highly reproducible. This technique holds promise for clinical studies and therapeutic trials.
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Affiliation(s)
- J B Caress
- Department of Neurology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157-1078, USA.
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Schnabel V, Struijk JJ. Magnetic and electrical stimulation of undulating nerve fibres: a simulation study. Med Biol Eng Comput 1999; 37:704-9. [PMID: 10723876 DOI: 10.1007/bf02513371] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.
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Affiliation(s)
- V Schnabel
- Center for Sensory-Motor Interaction, Aalborg University, Denmark.
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Yamanishi T, Yasuda K, Sakakibara R, Suda S, Ishikawa N, Hattori T, Hosaka H. Induction of urethral closure and inhibition of bladder contraction by continuous magnetic stimulation. Neurourol Urodyn 1999; 18:505-10. [PMID: 10494123 DOI: 10.1002/(sici)1520-6777(1999)18:5<505::aid-nau13>3.0.co;2-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Magnetic stimulation has been considered to be a technique for stimulating nervous system noninvasively and it has been used for experimental and clinical testings on the central and peripheral nervous systems. However, commercially available magnetic stimulators can only discharge single pulses for less than several minutes because the coil soon overheats. We newly devised a continuous magnetic stimulator assuring long-time stimulation, and this study was designed to confirm whether continuous magnetic stimulation would result in urethral closure and inhibition of bladder contraction in anesthetized canine models. Twelve female beagle dogs, weighing 9 to 12 kg, were anesthetized with a mixture of alpha-chloralose and urethane. In six beagles, a 4 F microtip transducer was inserted transurethrally, and maximum intraurethral pressure was monitored. In the remaining six animals, urethra was ligated at the bladder neck and a 4 F double lumen catheter was inserted from the dome of the bladder to infuse physiological saline, monitoring iso-volumetric rhythmic bladder contraction. The stimulating coil, of which temperature was kept at 20-25 degrees C by the built-in cooling system, was placed on the ishio-rectal fossa to stimulate the pudendal nerve at 10 Hz. The intraurethral pressure increased by 69.1 +/- 27.8 cm H(2)O, and iso-volumetric rhythmic bladder contraction was inhibited during the stimulation with 80% (240 Joule) of maximum output. In conclusion, continuous magnetic stimulator was found effective for urethral closure and inhibition of bladder contraction. Neurourol. Urodynam. 18:505-510, 1999.
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Affiliation(s)
- T Yamanishi
- Department of Urology, Chiba University, School of Medicine, Chiba, Japan
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Abstract
Magnetic nerve stimulation (MNS) using a novel figure-8 magnetic coil was compared with conventional electric nerve stimulation (ENS) in normal subjects and in patients with disorders of the peripheral nervous system. In contrast to previously tested coils, the virtual cathode of the novel coil was independent of the geometrical or electric conditions of the stimulated tissue. Maximal compound muscle action potentials (CMAPs) were elicited by MNS in all motor nerves tested. The slopes of the recruitment curves of ENS were steeper than those of MNS, indicating a comparatively lower maximal stimulation intensity and a higher intensity resolution of the magnetic stimulator. In four patients with entrapment syndromes at the ulnar groove, motor conduction velocities and amplitudes were similar for MNS and ENS across the affected nerve segment. However, in two patients with chronic inflammatory demyelinating polyneuropathy (CIDP), CMAPs were slightly smaller following MNS. This new technique is a promising step toward the ultimate goal of replacing ENS with MNS.
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Affiliation(s)
- F Binkofski
- Department of Neurology, University of Düsseldorf, Germany
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The use and abuse of magnets in healthcare. J Bodyw Mov Ther 1999. [DOI: 10.1016/s1360-8592(99)80025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
A 57-year-old woman developed rapidly progressive, symmetric, extremity weakness, facial diplegia, ophthalmoplegia, respiratory insufficiency, and sensory ataxia over a 3-week period. Electrodiagnostic studies were performed on days 6, 13, and 50 following the onset of weakness. Motor nerve conduction abnormalities were the predominant findings. Prolonged motor distal latencies, prolonged or absent F waves, and partial motor conduction blocks were present and form the diagnostic features of an acquired, demyelinating polyneuropathy. Abnormalities in sensory nerve conductions and blink reflexes were also present. Guillain-Barré syndrome was diagnosed prompting the initiation of therapeutic plasma exchange. The patient's clinical status continued to worsen over the next 10 days before stabilizing. Considerable improvement in extremity strength, ocular motility, and respiratory function occurred in the subsequent weeks. Well-planned and well-executed electrodiagnostic studies generate key adjunctive data to the clinical diagnosis of Guillain-Barré syndrome.
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Affiliation(s)
- D H Weinberg
- Department of Neurology, Tufts University School of Medicine, St. Elizabeth's Medical Center, Boston, Massachusetts 02135-2907, USA
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Kobayashi M, Ueno S, Kurokawa T. Importance of soft tissue inhomogeneity in magnetic peripheral nerve stimulation. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1997; 105:406-13. [PMID: 9363007 DOI: 10.1016/s0924-980x(97)00035-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In magnetic peripheral nerve stimulation with a figure-of-eight coil, a 'tangential-edge' coil orientation (the nerve is beneath the coil intersection and perpendicular to the coil wings) is ideal theoretically. However, some experimental results show that strong muscle responses are elicited with a 'symmetrical-tangential' coil orientation (the nerve is beneath the coil intersection and parallel to the coil wings), which is inconsistent with the cable theory. We hypothesized that the 10:1 conductivity difference between muscle and fat would cause inconsistent results during magnetic median nerve stimulation in the elbow, which was verified using an inhomogeneous volume conductor model. The induced electric fields were measured in a model composed of saline solutions of different concentrations divided by a cellophane sheet. A nerve was imagined along the boundary between the two solutions, and the coil was held in a 'symmetrical-tangential' position. Virtual cathodes, which were off the nerve in the homogeneous model, were on the nerve in the inhomogeneous model. The previous inconsistent results were explained by considering soft tissue inhomogeneity without any modification of the assumption in the cable theory that only the induced electric field component parallel to the nerve is responsible for nerve excitation.
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Affiliation(s)
- M Kobayashi
- Faculty of Medicine, University of Tokyo, Japan.
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Zhu Y, Starr A, Haldeman S, Fu H, Liu J, Wu P. Magnetic stimulation of muscle evokes cerebral potentials by direct activation of nerve afferents: a study during muscle paralysis. Muscle Nerve 1996; 19:1570-5. [PMID: 8941271 DOI: 10.1002/(sici)1097-4598(199612)19:12<1570::aid-mus6>3.0.co;2-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We tested the hypothesis that magnetic stimulation of muscle evokes cerebral potentials by causing a muscle contraction that then activates muscle receptors. We measured cerebral evoked potentials accompanying magnetic stimulation of muscle in 3 patients during surgery both before and after muscle paralysis with succinylcholine, a depolarizing agent. The magnetic stimulation was at low intensity (30%) and at a 2/s rate. The administration of succinylcholine sufficient to produce muscle paralysis did not alter cerebral potentials evoked by either low-intensity magnetic stimulation of muscle (gastrocnemius/soleus) or electrical stimulation of peripheral nerve (tibial nerve). In 1 normal subject, the S1 nerve root action potentials conducting at rapid velocity (> 60 m/s) were detected at the S1 foramen with a needle electrode using electrical stimulation of the tibial nerve. However, no S1 nerve root potentials could be identified to magnetic stimulation of muscle that evoked a cerebral potential. We conclude that magnetic stimulation of muscle activates terminal afferents in the muscle to provide the afferent drive for the cerebral potentials independent of muscle contraction. The failure to detect the afferent volley in S1 nerve root to magnetic stimulation suggests that only a few afferents are activated or that the activation of afferents is temporally dispersed.
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Affiliation(s)
- Y Zhu
- Department of Neurology, University of California, Irvine 92717, USA
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Ruohonen J, Ravazzani P, Nilsson J, Panizza M, Grandori F, Tognola G. A volume-conduction analysis of magnetic stimulation of peripheral nerves. IEEE Trans Biomed Eng 1996; 43:669-78. [PMID: 9216138 DOI: 10.1109/10.503174] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Magnetic stimulation is a method to study several nervous disorders as well as the intact nervous system in humans. Interest in magnetic stimulation of peripheral nerves has grown rapidly, but difficulties in locating the site of excitation have prevented it from becoming a routine clinical tool. It has been reasoned that the activating function of long and straight nerves is the first spatial derivative of the electric field component parallel to the nerves. Therefore, to predict the site of activation, one has to compute this field feature. We describe here an analytical mathematical model and investigate the influence of volume-conductor shape on the induced field. Predictions of the site of activation are given for typical stimulation coil arrangements and these results are compared with experimental and literature data. Comparisons suggest that the activating function is not simply the spatial gradient of the induced electric field, but that other mechanisms are also involved. The model can be easily utilized in the search for more efficient coil constructions and improved placements with respect to the target nerves.
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Affiliation(s)
- J Ruohonen
- Helsinki University Central Hospital, Medical Engineering Center, Finland
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