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Truong DQ, Thomas C, Ira S, Valter Y, Clark TK, Datta A. Unpacking Galvanic Vestibular Stimulation using simulations and relating current flow to reported motions: Comparison across common and specialized electrode placements. PLoS One 2024; 19:e0309007. [PMID: 39186497 PMCID: PMC11346646 DOI: 10.1371/journal.pone.0309007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 08/04/2024] [Indexed: 08/28/2024] Open
Abstract
BACKGROUND Galvanic Vestibular Stimulation (GVS) is a non-invasive electrical stimulation technique that is typically used to probe the vestibular system. When using direct current or very low frequency sine, GVS causes postural sway or perception of illusory (virtual) motions. GVS is commonly delivered using two electrodes placed at the mastoids, however, placements involving additional electrodes / locations have been employed. Our objective was to systematically evaluate all known GVS electrode placements, compare induced current flow, and how it relates to the archetypal sway and virtual motions. The ultimate goal is to help users in having a better understanding of the effects of different placements. METHODS We simulated seven GVS electrode placements with same total injected current using an ultra-high resolution model. Induced electric field (EF) patterns at the cortical and the level of vestibular organs (left and right) were determined. A range of current flow metrics including potential factors such as inter-electrode separation, percentage of current entering the cranial cavity, and symmetricity were calculated. Finally, we relate current flow to reported GVS motions. RESULTS As expected, current flow patterns are electrode placement specific. Placements with two electrodes generally result in higher EF magnitude. Placements with four electrodes result in lower percentage of current entering the cranial cavity. Symmetric placements do not result in similar EF values in the left and the right organs respectively- highlighting inherent anatomical asymmetry of the human head. Asymmetric placements were found to induce as much as ~3-fold higher EF in one organ over the other. The percentage of current entering the cranial cavity varies between ~15% and ~40% depending on the placement. CONCLUSIONS We expect our study to advance understanding of GVS and provide insight on probable mechanism of action of a certain electrode placement choice. The dataset generated across several metrics will support hypothesis testing relating empirical outcomes to current flow patterns. Further, the differences in current flow will guide stimulation strategy (what placement and how much scalp current to use) and facilitate a quantitatively informed rational / optimal decision.
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Affiliation(s)
- Dennis Q. Truong
- Research and Development, Soterix Medical, Woodbridge, New Jersey, United States of America
| | - Chris Thomas
- Research and Development, Soterix Medical, Woodbridge, New Jersey, United States of America
| | - Sanjidah Ira
- Research and Development, Soterix Medical, Woodbridge, New Jersey, United States of America
| | - Yishai Valter
- Research and Development, Soterix Medical, Woodbridge, New Jersey, United States of America
| | - Torin K. Clark
- Smead Aerospace Engineering Sciences Department, College of Engineering and Applied Science, University of Colorado, Boulder, Colorado, United States of America
| | - Abhishek Datta
- Research and Development, Soterix Medical, Woodbridge, New Jersey, United States of America
- Biomedical Engineering, City College of New York, New York, New York, United States of America
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Couppey T, Regnacq L, Giraud R, Romain O, Bornat Y, Kolbl F. NRV: An open framework for in silico evaluation of peripheral nerve electrical stimulation strategies. PLoS Comput Biol 2024; 20:e1011826. [PMID: 38995970 PMCID: PMC11268605 DOI: 10.1371/journal.pcbi.1011826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 07/24/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
Electrical stimulation of peripheral nerves has been used in various pathological contexts for rehabilitation purposes or to alleviate the symptoms of neuropathologies, thus improving the overall quality of life of patients. However, the development of novel therapeutic strategies is still a challenging issue requiring extensive in vivo experimental campaigns and technical development. To facilitate the design of new stimulation strategies, we provide a fully open source and self-contained software framework for the in silico evaluation of peripheral nerve electrical stimulation. Our modeling approach, developed in the popular and well-established Python language, uses an object-oriented paradigm to map the physiological and electrical context. The framework is designed to facilitate multi-scale analysis, from single fiber stimulation to whole multifascicular nerves. It also allows the simulation of complex strategies such as multiple electrode combinations and waveforms ranging from conventional biphasic pulses to more complex modulated kHz stimuli. In addition, we provide automated support for stimulation strategy optimization and handle the computational backend transparently to the user. Our framework has been extensively tested and validated with several existing results in the literature.
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Affiliation(s)
- Thomas Couppey
- Laboratoire ETIS, Cergy Paris Université, ENSEA, CNRS UMR 8051, Cergy, France
| | - Louis Regnacq
- Laboratoire ETIS, Cergy Paris Université, ENSEA, CNRS UMR 8051, Cergy, France
- Univ. Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, Talence, France
| | - Roland Giraud
- Laboratoire ETIS, Cergy Paris Université, ENSEA, CNRS UMR 8051, Cergy, France
- Univ. Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, Talence, France
| | - Olivier Romain
- Laboratoire ETIS, Cergy Paris Université, ENSEA, CNRS UMR 8051, Cergy, France
| | - Yannick Bornat
- Univ. Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, Talence, France
| | - Florian Kolbl
- Laboratoire ETIS, Cergy Paris Université, ENSEA, CNRS UMR 8051, Cergy, France
- Univ. Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, Talence, France
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Scarpelli A, Stefano M, Cordella F, Zollo L. Evaluation of the effects of focused ultrasound stimulation on the central nervous system through a multiscale simulation approach. Front Bioeng Biotechnol 2022; 10:1034194. [DOI: 10.3389/fbioe.2022.1034194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
The lack of sensory feedback represents one of the main drawbacks of commercial upper limb prosthesis. Transcranial Focused Ultrasound Stimulation (tFUS) seems to be a valid non-invasive technique for restoring sensory feedback allowing to deliver acoustic energy to cortical sensory areas with high spatial resolution and depth penetration. This paper aims at studying in simulation the use of tFUS on cortical sensory areas to evaluate its effects in terms of latency ad firing rate of the cells response, for understanding if these parameters influence the safety and the efficacy of the stimulation. In this paper, in order to study the propagation of the ultrasound wave from the transducer to the cortical cells, a multiscale approach was implemented by building a macroscopic model, which estimates the pressure profile in a simplified 2D human head geometry, and coupling it with the SONIC microscale model, that describes the electrical behaviour of a cortical neuron. The influence of the stimulation parameters and of the skull thickness on the latency and the firing rate are evaluated and the obtained behaviour is linked to the sensory response obtained on human subjects. Results have shown that slight changes in the transducer position should not affect the efficacy of the stimulation; however, high skull thickness leads to lower cells activation. These results will be useful for evaluating safety and effectiveness of tFUS for sensory feedback in closed-loop prosthetic systems.
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Salkim E, Zamani M, Jiang D, Saeed SR, Demosthenous A. Insertion Guidance Based on Impedance Measurements of a Cochlear Electrode Array. Front Comput Neurosci 2022; 16:862126. [PMID: 35814346 PMCID: PMC9260075 DOI: 10.3389/fncom.2022.862126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/18/2022] [Indexed: 11/30/2022] Open
Abstract
The cochlear implantable neuromodulator provides substantial auditory perception to those with severe or profound impaired hearing. Correct electrode array positioning in the cochlea is one of the important factors for quality hearing, and misplacement may lead to additional injury to the cochlea. Visual inspection of the progress of electrode insertion is limited and mainly relies on the surgeon's tactile skills, and there is a need to detect in real-time the electrode array position in the cochlea during insertion. The available clinical measurement presently provides very limited information. Impedance measurement may be used to assist with the insertion of the electrode array. Using computational modeling of the cochlea, and its local tissue layers merging with the associated neuromodulator electrode array parameters, the impedance variations at different insertion depths and the proximities to the cochlea walls have been analyzed. In this study, an anatomical computational model of the temporal region of a patient is used to derive the relationship between impedance variations and the electrode proximity to the cochlea wall and electrode insertion depth. The aim was to examine whether the use of electrode impedance variations can be an effective marker of electrode proximity and electrode insertion depth. The proposed anatomical model simulates the quasi-static electrode impedance variations at different selected points but at considerable computation cost. A much less computationally intensive geometric model (~1/30) provided comparative impedance measurements with differences of <2%. Both use finite element analysis over the entire cross-section area of the scala tympani. It is shown that the magnitude of the impedance varies with both electrode insertion depth and electrode proximity to the adjacent anatomical layers (e.g., cochlea wall). In particular, there is a 1,400% increase when the electrode array is moved very close to the cochlea wall. This may help the surgeon to find the optimal electrode position within the scala tympani by observation of such impedance characteristics. The misplacement of the electrode array within the scala tympani may be eliminated by using the impedance variation metric during electrode array insertion if the results are validated with an experimental study.
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Affiliation(s)
- Enver Salkim
- Department of Electronic and Electrical Engineering, University College London (UCL), London, United Kingdom
- Department of Electronic and Electrical Engineering, Biomedical Device Technology Group, Muş Alparslan University, Muş, Turkey
- *Correspondence: Enver Salkim
| | - Majid Zamani
- Department of Electronic and Electrical Engineering, University College London (UCL), London, United Kingdom
| | - Dai Jiang
- Department of Electronic and Electrical Engineering, University College London (UCL), London, United Kingdom
| | | | - Andreas Demosthenous
- Department of Electronic and Electrical Engineering, University College London (UCL), London, United Kingdom
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Abdul Halim SF, Zakaria Z, Pusppanathan J, Mohd Noor A, Norali AN, Fazalul Rahiman MH, Mohd Muji SZ, Abdul Rahim R, Engku-Husna EI, Ali Hassan MK, Aziz Safar MJ, Salleh AF, Mat Som MH. A Review on Magnetic Induction Spectroscopy Potential for Fetal Acidosis Examination. SENSORS 2022; 22:s22041334. [PMID: 35214235 PMCID: PMC8963069 DOI: 10.3390/s22041334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/24/2021] [Accepted: 01/07/2022] [Indexed: 02/06/2023]
Abstract
Fetal acidosis is one of the main concerns during labor. Currently, fetal blood sampling (FBS) has become the most accurate measurement of acidosis detection. However, it is invasive and does not provide a real time measurement due to laboratory procedures. Delays in diagnosis of acidosis have caused serious injury to the fetus, especially for the brain and the heart. This paper reviews the new technique in diagnosis of acidosis non-invasively. Magnetic Induction Spectroscopy (MIS) has been proposed to be a new device for acidosis detection in recent years. This paper explains the basic principle of MIS and outlines the design specifications and design considerations for a MIS pH probe. It is expected that readers will gain a basic understanding of the development of a MIS pH probe from this review.
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Affiliation(s)
- Siti Fatimah Abdul Halim
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
| | - Zulkarnay Zakaria
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
- Correspondence:
| | - Jaysuman Pusppanathan
- Sport Innovation & Technology Centre (SiTC), Institute of Human Centered Engineering (iHumen), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia;
| | - Anas Mohd Noor
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
| | - Ahmad Nasrul Norali
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
| | | | - Siti Zarina Mohd Muji
- Department of Electronic Engineering, Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat 86400, Johor, Malaysia;
| | - Ruzairi Abdul Rahim
- School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia;
| | - Engku Ismail Engku-Husna
- Department of Obstetrics and Gynaecology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia;
| | - Muhamad Khairul Ali Hassan
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
- Faculty of Electrical Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia;
| | - Muhammad Juhairi Aziz Safar
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
- Faculty of Electrical Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia;
| | - Ahmad Faizal Salleh
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
| | - Mohd Hanafi Mat Som
- Biomedical Electronic Engineering, Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (S.F.A.H.); (A.M.N.); (A.N.N.); (A.F.S.); (M.H.M.S.)
- Medical Device & Life Sciences Cluster, Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Perlis, Malaysia; (M.K.A.H.); (M.J.A.S.)
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