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Xu R, Treeby BE, Martin E. Safety Review of Therapeutic Ultrasound for Spinal Cord Neuromodulation and Blood-Spinal Cord Barrier Opening. ULTRASOUND IN MEDICINE & BIOLOGY 2024; 50:317-331. [PMID: 38182491 DOI: 10.1016/j.ultrasmedbio.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 01/07/2024]
Abstract
New focused ultrasound spinal cord applications have emerged, particularly those improving therapeutic agent delivery to the spinal cord via blood-spinal cord barrier opening and the neuromodulation of spinal cord tracts. One hurdle in the development of these applications is safety. It may be possible to use safety trends from seminal and subsequent works in focused ultrasound to guide the development of safety guidelines for spinal cord applications. We collated data from decades of pre-clinical studies and illustrate a clear relationship between damage, time-averaged spatial peak intensity and exposure duration. This relationship suggests a thermal mechanism underlies ultrasound-induced spinal cord damage. We developed minimum and mean thresholds for damage from these pre-clinical studies. When these thresholds were plotted against the parameters used in recent pre-clinical ultrasonic spinal cord neuromodulation studies, the majority of the neuromodulation studies were near or above the minimum threshold. This suggests that a thermal neuromodulatory effect may exist for ultrasonic spinal cord neuromodulation, and that the thermal dose must be carefully controlled to avoid damage to the spinal cord. By contrast, the intensity-exposure duration threshold had no predictive value when applied to blood-spinal cord barrier opening studies that employed injected contrast agents. Most blood-spinal cord barrier opening studies observed slight to severe damage, except for small animal studies that employed an active feedback control method to limit pressures based on measured bubble oscillation behavior. The development of new focused ultrasound spinal cord applications perhaps reflects the recent success in the development of focused ultrasound brain applications, and recent work has begun on the translation of these technologies from brain to spinal cord. However, a great deal of work remains to be done, particularly with respect to developing and accepting safety standards for these applications.
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Affiliation(s)
- Rui Xu
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
| | - Bradley E Treeby
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Eleanor Martin
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
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2
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Guinjoan SM. Personalized Definition of Surgical Targets in Major Depression and Obsessive-Compulsive Disorder: A Potential Role for Low-Intensity Focused Ultrasound? PERSONALIZED MEDICINE IN PSYCHIATRY 2023; 37-38:100100. [PMID: 36969502 PMCID: PMC10034711 DOI: 10.1016/j.pmip.2023.100100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Major Depressive Disorder (MDD) and Obsessive-Compulsive Disorder (OCD) are common and potentially incapacitating conditions. Even when recognized and adequately treated, in over a third of patients with these conditions the response to first-line pharmacological and psychotherapeutic measures is not satisfactory. After more assertive measures including pharmacological augmentation (and in the case of depression, transcranial magnetic stimulation, electroconvulsive therapy, or treatment with ketamine or esketamine), a significant number of individuals remain severely symptomatic. In these persons, different ablation and deep-brain stimulation (DBS) psychosurgical techniques have been employed. However, apart from the cost and potential morbidity associated with surgery, on average only about half of patients show adequate response, which limits the widespread application of these potentially life-saving interventions. Possible reasons are considered for the wide variation in outcomes across different series of patients with MDD or OCD exposed to ablative or DBS psychosurgery, including interindividual anatomical and etiological variability. Low-intensity focused ultrasound (LIFU) is an emerging technique that holds promise in its ability to achieve anatomically circumscribed, noninvasive, and reversible neuromodulation of deep brain structures. A possible role for LIFU in the personalized presurgical definition of neuromodulation targets in the individual patient is discussed, including a proposed roadmap for clinical trials addressed at testing whether this technique can help to improve psychosurgical outcomes.
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Affiliation(s)
- Salvador M Guinjoan
- Laureate Institute for Brain Research and Department of Psychiatry, Oklahoma University Health Sciences Center at Tulsa
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3
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Collins MN, Mesce KA. A review of the bioeffects of low-intensity focused ultrasound and the benefits of a cellular approach. Front Physiol 2022; 13:1047324. [PMID: 36439246 PMCID: PMC9685663 DOI: 10.3389/fphys.2022.1047324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 10/25/2022] [Indexed: 10/28/2023] Open
Abstract
This review article highlights the historical developments and current state of knowledge of an important neuromodulation technology: low-intensity focused ultrasound. Because compelling studies have shown that focused ultrasound can modulate neuronal activity non-invasively, especially in deep brain structures with high spatial specificity, there has been a renewed interest in attempting to understand the specific bioeffects of focused ultrasound at the cellular level. Such information is needed to facilitate the safe and effective use of focused ultrasound to treat a number of brain and nervous system disorders in humans. Unfortunately, to date, there appears to be no singular biological mechanism to account for the actions of focused ultrasound, and it is becoming increasingly clear that different types of nerve cells will respond to focused ultrasound differentially based on the complement of their ion channels, other membrane biophysical properties, and arrangement of synaptic connections. Furthermore, neurons are apparently not equally susceptible to the mechanical, thermal and cavitation-related consequences of focused ultrasound application-to complicate matters further, many studies often use distinctly different focused ultrasound stimulus parameters to achieve a reliable response in neural activity. In this review, we consider the benefits of studying more experimentally tractable invertebrate preparations, with an emphasis on the medicinal leech, where neurons can be studied as unique individual cells and be synaptically isolated from the indirect effects of focused ultrasound stimulation on mechanosensitive afferents. In the leech, we have concluded that heat is the primary effector of focused ultrasound neuromodulation, especially on motoneurons in which we observed a focused ultrasound-mediated blockade of action potentials. We discuss that the mechanical bioeffects of focused ultrasound, which are frequently described in the literature, are less reliably achieved as compared to thermal ones, and that observations ascribed to mechanical responses may be confounded by activation of synaptically-coupled sensory structures or artifacts associated with electrode resonance. Ultimately, both the mechanical and thermal components of focused ultrasound have significant potential to contribute to the sculpting of specific neural outcomes. Because focused ultrasound can generate significant modulation at a temperature <5°C, which is believed to be safe for moderate durations, we support the idea that focused ultrasound should be considered as a thermal neuromodulation technology for clinical use, especially targeting neural pathways in the peripheral nervous system.
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Affiliation(s)
- Morgan N. Collins
- Graduate Program in Neuroscience, University of Minnesota, Saint Paul, MN, United States
| | - Karen A. Mesce
- Department of Entomology and Graduate Program in Neuroscience, University of Minnesota, Saint Paul, MN, United States
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Mechanistic insights into ultrasonic neurostimulation of disconnected neurons using single short pulses. Brain Stimul 2022; 15:769-779. [PMID: 35561960 DOI: 10.1016/j.brs.2022.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 04/27/2022] [Accepted: 05/03/2022] [Indexed: 02/06/2023] Open
Abstract
Ultrasonic neurostimulation is a potentially potent noninvasive therapy, whose mechanism has yet to be elucidated. We designed a system capable of applying ultrasound with minimal reflections to neuronal cultures. Synaptic transmission was pharmacologically controlled, eliminating network effects, enabling examination of single-cell processes. Short single pulses of low-intensity ultrasound were applied, and time-locked responses were examined using calcium imaging. Low-pressure (0.35MPa) ultrasound directly stimulated ∼20% of pharmacologically disconnected neurons, regardless of membrane poration. Stimulation was resistant to the blockade of several purinergic receptor and mechanosensitive ion channel types. Stimulation was blocked, however, by suppression of action potentials. Surprisingly, even extremely short (4μs) pulses were effective, stimulating ∼8% of the neurons. Lower-pressure pulses (0.35MPa) were less effective than higher-pressure ones (0.65MPa). Attrition effects dominated, with no indication of compromised viability. Our results detract from theories implicating cavitation, heating, non-transient membrane pores >1.5nm, pre-synaptic release, or gradual effects. They implicate a post-synaptic mechanism upstream of the action potential, and narrow down the list of possible targets involved.
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Darmani G, Bergmann T, Butts Pauly K, Caskey C, de Lecea L, Fomenko A, Fouragnan E, Legon W, Murphy K, Nandi T, Phipps M, Pinton G, Ramezanpour H, Sallet J, Yaakub S, Yoo S, Chen R. Non-invasive transcranial ultrasound stimulation for neuromodulation. Clin Neurophysiol 2022; 135:51-73. [DOI: 10.1016/j.clinph.2021.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 12/13/2022]
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Lemaire T, Vicari E, Neufeld E, Kuster N, Micera S. MorphoSONIC: A morphologically structured intramembrane cavitation model reveals fiber-specific neuromodulation by ultrasound. iScience 2021; 24:103085. [PMID: 34585122 PMCID: PMC8456061 DOI: 10.1016/j.isci.2021.103085] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/02/2021] [Accepted: 09/01/2021] [Indexed: 11/10/2022] Open
Abstract
Low-Intensity Focused Ultrasound Stimulation (LIFUS) holds promise for the remote modulation of neural activity, but an incomplete mechanistic characterization hinders its clinical maturation. Here we developed a computational framework to model intramembrane cavitation (a candidate mechanism) in multi-compartment, morphologically structured neuron models, and used it to investigate ultrasound neuromodulation of peripheral nerves. We predict that by engaging membrane mechanoelectrical coupling, LIFUS exploits fiber-specific differences in membrane conductance and capacitance to selectively recruit myelinated and/or unmyelinated axons in distinct parametric subspaces, allowing to modulate their activity concurrently and independently over physiologically relevant spiking frequency ranges. These theoretical results consistently explain recent empirical findings and suggest that LIFUS can simultaneously, yet selectively, engage different neural pathways, opening up opportunities for peripheral neuromodulation currently not addressable by electrical stimulation. More generally, our framework is readily applicable to other neural targets to establish application-specific LIFUS protocols.
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Affiliation(s)
- Théo Lemaire
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1202 Lausanne, Switzerland
| | - Elena Vicari
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1202 Lausanne, Switzerland
- Biorobotics Institute, Scuola Superiore Sant’Anna (SSSA), 56127 Pisa, Italy
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland
| | - Niels Kuster
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland
- Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH) Zurich, 8092 Zurich, Switzerland
| | - Silvestro Micera
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1202 Lausanne, Switzerland
- Biorobotics Institute, Scuola Superiore Sant’Anna (SSSA), 56127 Pisa, Italy
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7
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Collins MN, Legon W, Mesce KA. The Inhibitory Thermal Effects of Focused Ultrasound on an Identified, Single Motoneuron. eNeuro 2021; 8:ENEURO.0514-20.2021. [PMID: 33853851 PMCID: PMC8174046 DOI: 10.1523/eneuro.0514-20.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 03/18/2021] [Accepted: 03/28/2021] [Indexed: 12/30/2022] Open
Abstract
Focused ultrasound (US) is an emerging neuromodulation technology that has gained much attention because of its ability to modulate, noninvasively, neuronal activity in a variety of animals, including humans. However, there has been considerable debate about exactly which types of neurons can be influenced and what underlying mechanisms are in play. Are US-evoked motor changes driven indirectly by activated mechanosensory inputs, or more directly via central interneurons or motoneurons? Although it has been shown that US can mechanically depolarize mechanosensory neurons, there are no studies that have yet tested how identified motoneurons respond directly to US and what the underlying mechanism might be. Here, we examined the effects of US on a single, identified motoneuron within a well-studied and tractable invertebrate preparation, the medicinal leech, Hirudo verbana Our approach aimed to clarify single neuronal responses to US, which may be obscured in other studies whereby US is applied across a diverse population of cells. We found that US has the ability to inhibit tonic spiking activity through a predominately thermal mechanism. US-evoked effects persisted after blocking synaptic inputs, indicating that its actions were direct. Experiments also revealed that US-comparable heating blocked the axonal conduction of spontaneous action potentials. Finally, we found no evidence that US had significant mechanical effects on the neurons tested, a finding counter to prevailing views. We conclude that a non-sensory neuron can be directly inhibited via a thermal mechanism, a finding that holds promise for clinical neuromodulatory applications.
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Affiliation(s)
- Morgan N Collins
- Graduate Program in Neuroscience, University of Minnesota, St. Paul, MN 55108
| | - Wynn Legon
- Department of Neurological Surgery, School of Medicine, University of Virginia, Charlottesville, VA 22901
| | - Karen A Mesce
- Graduate Program in Neuroscience, University of Minnesota, St. Paul, MN 55108
- Departments of Entomology and Neuroscience, University of Minnesota, St. Paul, MN 55108
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8
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Wasilczuk KM, Bayer KC, Somann JP, Albors GO, Sturgis J, Lyle LT, Robinson JP, Irazoqui PP. Modulating the Inflammatory Reflex in Rats Using Low-Intensity Focused Ultrasound Stimulation of the Vagus Nerve. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:481-489. [PMID: 30396599 DOI: 10.1016/j.ultrasmedbio.2018.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/31/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
Tumor necrosis factor α (TNF-α) is linked to several chronic inflammatory diseases. Electrical vagus nerve stimulation reduces serum TNF-α levels but may cause chronic nerve damage and requires surgery. Alternatively, we proposed focused ultrasound stimulation of the vagus nerve (uVNS), which can be applied non-invasively. In this study, we induced an inflammatory response in rats using lipopolysaccharides (LPS) and collected blood to analyze the effects of uVNS on cytokine concentrations. We applied one or three 5-min pulsed focused ultrasound stimulation treatments to the vagus nerve (250 kHz, ISPPA = 3 W/cm2). Animals receiving a single ultrasound application had an average reduction in TNF-α levels of 19%, similar to the 16% reduction observed in electrically stimulated animals. With multiple applications, uVNS therapy statistically reduced serum TNF-α levels by 73% compared with control animals without any observed damage to the nerve. These findings suggest that uVNS is a suitable way to attenuate TNF-α levels.
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Affiliation(s)
- Kelsey M Wasilczuk
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA.
| | - Kelsey C Bayer
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Jesse P Somann
- Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Gabriel O Albors
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Jennifer Sturgis
- Purdue University Cytometry Laboratories, Purdue University, West Lafayette, Indiana, USA
| | - L Tiffany Lyle
- College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - J Paul Robinson
- Purdue University Cytometry Laboratories, Purdue University, West Lafayette, Indiana, USA
| | - Pedro P Irazoqui
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA; Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA
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9
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Abstract
For more than 70 years, the promise of noninvasive neuromodulation using focused ultrasound has been growing while diagnostic ultrasound established itself as a foundation of clinical imaging. Significant technical challenges have been overcome to allow transcranial focused ultrasound to deliver spatially restricted energy into the nervous system at a wide range of intensities. High-intensity focused ultrasound produces reliable permanent lesions within the brain, and low-intensity focused ultrasound has been reported to both excite and inhibit neural activity reversibly. Despite intense interest in this promising new platform for noninvasive, highly focused neuromodulation, the underlying mechanism remains elusive, though recent studies provide further insight. Despite the barriers, the potential of focused ultrasound to deliver a range of permanent and reversible neuromodulation with seamless translation from bench to the bedside warrants unparalleled attention and scientific investment. Focused ultrasound boasts a number of key features such as multimodal compatibility, submillimeter steerable focusing, multifocal, high temporal resolution, coregistration, and the ability to monitor delivered therapy and temperatures in real time. Despite the technical complexity, the future of noninvasive focused ultrasound for neuromodulation as a neuroscience and clinical platform remains bright.
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Affiliation(s)
- David P Darrow
- Department of Neurosurgery, University of Minnesota, 420 Delaware St SE, MMC 96, Room D-429, Minneapolis, MN, 55455, USA.
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10
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Baek H, Pahk KJ, Kim H. A review of low-intensity focused ultrasound for neuromodulation. Biomed Eng Lett 2017; 7:135-142. [PMID: 30603160 PMCID: PMC6208465 DOI: 10.1007/s13534-016-0007-y] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 11/05/2016] [Accepted: 11/16/2016] [Indexed: 12/14/2022] Open
Abstract
The ability of ultrasound to be focused into a small region of interest through the intact skull within the brain has led researchers to investigate its potential therapeutic uses for functional neurosurgery and tumor ablation. Studies have used high-intensity focused ultrasound to ablate tissue in localised brain regions for movement disorders and chronic pain while sparing the overlying and surrounding tissue. More recently, low-intensity focused ultrasound (LIFU) that induces reversible biological effects has been emerged as an alternative neuromodulation modality due to its bi-modal (i.e. excitation and suppression) capability with exquisite spatial specificity and depth penetration. Many compelling evidences of LIFU-mediated neuromodulatory effects including behavioral responses, electrophysiological recordings and functional imaging data have been found in the last decades. LIFU, therefore, has the enormous potential to improve the clinical outcomes as well as to replace the currently available neuromodulation techniques such as deep brain stimulation (DBS), transcranial magnetic stimulation and transcranial current stimulation. In this paper, we aim to provide a summary of pioneering studies in the field of ultrasonic neuromodulation including its underlying mechanisms that were published in the last 60 years. In closing, some of potential clinical applications of ultrasonic brain stimulation will be discussed.
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Affiliation(s)
- Hongchae Baek
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
| | - Ki Joo Pahk
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
| | - Hyungmin Kim
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
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11
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Abstract
Ultrasonic waves can be non-invasively steered and focused into mm-scale regions across the human body and brain, and their application in generating controlled artificial modulation of neuronal activity could therefore potentially have profound implications for neural science and engineering. Ultrasonic neuro-modulation phenomena were experimentally observed and studied for nearly a century, with recent discoveries on direct neural excitation and suppression sparking a new wave of investigations in models ranging from rodents to humans. In this paper we review the physics, engineering and scientific aspects of ultrasonic fields, their control in both space and time, and their effect on neuronal activity, including a survey of both the field's foundational history and of recent findings. We describe key constraints encountered in this field, as well as key engineering systems developed to surmount them. In closing, the state of the art is discussed, with an emphasis on emerging research and clinical directions.
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Affiliation(s)
- Omer Naor
- Department of Biomedical Engineering, The Technion-Israel Institute of Technology Haifa 32000, Israel. The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91220, Israel
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12
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Khraiche ML, Phillips WB, Jackson N, Muthuswamy J. Ultrasound induced increase in excitability of single neurons. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:4246-9. [PMID: 19163650 DOI: 10.1109/iembs.2008.4650147] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The aim of this study was to carefully assess the level of modulation in electrical excitability of single neurons with the application of high frequency ultrasound. High frequency tone bursts of ultrasound have been shown to dramatically increase the spike frequency of primary hippocampal neurons in culture. In addition, these ultrasonic bursts also induce silent or still developing neurons to fire. Results indicate that the increase in excitability is largely mediated by mechanical effects and not thermal effects of ultrasound. Future studies on culture models exposed to varying ultrasound protocols may provide insight into the feasibility of using ultrasound as a means for neurostimulation studies conducted on brain slice and in vivo models.
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Affiliation(s)
- Massoud L Khraiche
- Harrington Department of Bioengineering, Arizona State University, Tempe 85287, USA
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13
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Foley JL, Little JW, Vaezy S. Effects of high-intensity focused ultrasound on nerve conduction. Muscle Nerve 2008; 37:241-50. [DOI: 10.1002/mus.20932] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Phillips WB, Larson PJ, Towe BC. Ultrasonically-assisted intracortical microstimulation of the rat. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:4217-20. [PMID: 17271234 DOI: 10.1109/iembs.2004.1404176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
High frequency tone bursts of ultrasound are capable of increasing the sensitivity of rat motor cortex to electrical stimulation. In this study, 11.75 MHz ultrasound pre-stimuli were delivered to the forelimb motor region of the rat cortex followed by an electrical pulse train to assess changes in cortical activation. The temporal peak intensity of the ultrasound delivered to the brain ranged from 100 to 150 W/cm(2). Tone bursts of 10 to 50 ms in duration were delivered once per second over periods of 30 to 240 seconds. The intracortical microstimulation (ICMS) current needed for forepaw motor response decreased by as much as 40% when applying 50 ms ultrasound pulses. Brain excitability changes were seen with a thermal index (TI) as low as 2.0. Ultrasound application alone was not able to induce motor responses.
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Affiliation(s)
- William B Phillips
- Harrington Department of Bioengineering, Arizona State University, Tempe, AZ, USA
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15
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Foley JL, Little JW, Vaezy S. Image-Guided High-Intensity Focused Ultrasound for Conduction Block of Peripheral Nerves. Ann Biomed Eng 2006; 35:109-19. [PMID: 17072498 DOI: 10.1007/s10439-006-9162-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 07/10/2006] [Indexed: 11/26/2022]
Abstract
The objective of our work has been to investigate the use of ultrasound image-guided high-intensity focused ultrasound (HIFU) to non-invasively produce conduction block in rabbit sciatic nerves in vivo, a technique that could become a treatment of spasticity and pain. The work reported here involved the investigation of the duration of such conduction blocks after HIFU treatment and whether they resulted in axon degeneration. The right sciatic nerves of 12 rabbits were treated, under guidance of ultrasound imaging, with repeated 5-s applications of 3.2 MHz HIFU with in situ intensity of 1930 W/cm(2) (spatial-average, temporal-average) until conduction block was achieved. Survival endpoints were 0, 7, or 14 days after HIFU treatment, at which point the nerve conduction was assessed. Qualitative and quantitative histological analysis of nerve sections proximal and distal to the HIFU site was performed. Conduction block of all 12 nerves was achieved with average HIFU treatment time of 10.5+/-4.9 s (mean+/-SD). The volume of necrosis of adjacent muscle was measured to be 1.59+/-1.1 cm(3) (mean+/-SD). For all nerves, conduction block remained at the survival endpoint and the block resulted in degeneration of axons distal to the HIFU site, as confirmed by electrophysiological and histological methods. Potential clinical applications include treatment of spasticity in patients with spinal cord injury or pain in cancer patients.
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Affiliation(s)
- Jessica L Foley
- Department of Bioengineering, University of Washington, Box 355061, Seattle, WA 98195, USA
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16
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Foley JL, Little JW, Starr FL, Frantz C, Vaezy S. Image-guided HIFU neurolysis of peripheral nerves to treat spasticity and pain. ULTRASOUND IN MEDICINE & BIOLOGY 2004; 30:1199-1207. [PMID: 15550323 DOI: 10.1016/j.ultrasmedbio.2004.07.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Revised: 06/17/2004] [Accepted: 07/08/2004] [Indexed: 05/24/2023]
Abstract
Spasticity, a major complication of central nervous system disorders, signified by uncontrollable muscle contractions, is very difficult to treat effectively. We report on the use of ultrasound (US) image-guided high-intensity focused US (HIFU) to target and suppress the function of the sciatic nerve complex of rabbits in vivo, as a possible treatment of spasticity. The image-guided HIFU device included a 3.2-MHz spherically curved transducer and an intraoperative imaging probe. A focal acoustic intensity of 1480 to 1850 W/cm(2), applied using a scanning method, was effective in achieving complete conduction block in 100% of 22 nerve complexes with HIFU treatment times of 36 +/- 14 s (mean +/- SD). Gross examination showed blanching of the nerve at the HIFU treatment site and lesion volumes of 2.8 +/- 1.4 cm(3) encompassing the nerve complex. Histologic examination indicated axonal demyelination and necrosis of Schwann cells as probable mechanisms of nerve block. With accurate localization and targeting of peripheral nerves using US imaging, HIFU could become a promising tool for the suppression of spasticity.
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Affiliation(s)
- Jessica L Foley
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
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17
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Rinaldi PC, Jones JP, Reines F, Price LR. Modification by focused ultrasound pulses of electrically evoked responses from an in vitro hippocampal preparation. Brain Res 1991; 558:36-42. [PMID: 1933382 DOI: 10.1016/0006-8993(91)90711-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The application of short pulses of focused ultrasound was studied as a method of modifying electrically evoked responses in the mammalian brain. The in vitro hippocampal preparation was employed to facilitate delivery and dosimetry of ultrasound, and assessment of mechanisms of ultrasound effects. Cellular and dendritic field potential responses evoked by electrical stimulation of the Schaffer/Commissural afferents were examined before, during and after exposure of a portion of the CA1 region to focused ultrasound pulses for periods ranging from 2 to 15 min. Focused ultrasound with a repetition rate of 150 kHz was delivered in pulses comparable in duration to an electrical pulse that could initiate activity in the nervous system. The pulses had a center frequency of 750 kHz, durations of about 6 microseconds, and spatial-peak-temporal-averaged intensities of about 80 W/cm2. These parameters are markedly different from those employed in conventional diagnostic ultrasound. Temperatures in the bath and tissue were monitored. Extracellular field potentials reflecting the presynaptic fiber volley, dendritic response and cellular discharge were significantly reduced by exposure to ultrasound. Recovery occurred to varying degrees, and in one experiment was complete. Average temperature changes observed were less than 1 degree C. The present study demonstrates that the electrically evoked response in mammalian brain can be altered by ultrasound in a non-thermal, non-cavitational mode, and that such effects are potentially reversible.
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Affiliation(s)
- P C Rinaldi
- Department of Surgery, University of California, Irvine 92717
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Tebecis AK, Phillis JW. Reflex response changes of the toad spinal cord to variations in temperature and pH. ACTA ACUST UNITED AC 1968; 25:1035-47. [PMID: 5758864 DOI: 10.1016/0010-406x(68)90589-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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