A Comprehensive View of Electrosleep: The History, Finite Element Models and Future Directions

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. This is concluded with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES. Despite this history, questions regarding the efficacy of ES remain including optimal dose (electrode placement and waveform). An investigation into brain electric field and current density produced by various montages that are historically relevant to ES was done to evaluate how these montages effect the brain. MRI-derived head models that were segmented using an automated segmentation algorithm and manual corrections were solved for four different electrode montages. The montages that were used are as follows: Sponge electrode on left and right eyes (active), Sponge electrodes over left and right mastoids (return); Sponge electrodes above left and right eyes (active), Sponge electrodes over left and right mastoids (return); High-Definition (HD) electrodes on AF3 and AF4 (active), 5x7 cm sponge on neck (return); HD electrodes on AF3 and AF4 (active), 5x7 sponge electrode on Iz (return). A high concentration of electric field was found on the optic nerve, with levels lowered as the electrodes moved further away from the eyes. There was also a moderate current density on the amygdala, a center involved with anxiety, as well as high electric fields on the brain stem which are centers for sleep. Using the models that were run for the electrosleep inspired montages the montage that was selected for the proposed experiment was to use anodes on AF3 and AF4 with the cathode on Iz. The anodes will be HD electrodes while the cathode will be a 5x7 cm sponge. Subjects will be split into 4 groups of 8 people each and will receive two legs of stimulation spaced one week apart. One leg will have current of 2 mA, 1 mA, 0.5 mA or sham while the other leg is all sham and the order in which they receive it will be randomized. Subjects will be stimulated for 20 minutes at 100 Hz and will spend a total of 40 minutes during the experiment where they will have their eyes recorded with an IR sensitive camera and they will be required to perform an odd-tone response task. Subjects are expected to fall asleep faster with higher levels of current and there is no added effect from baseline expected for subjects who receive sham stimulatio

Finite Element Study of Transcranial Direct Current Stimulation: customization of models and montages

Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation technique that applies low amplitude current via electrodes placed on the scalp. Rather than directly eliciting a neuronal response, tDCS is believed to modulate excitability – encouraging or suppressing activity in regions of the brain depending on the polarity of stimulation. The particular application of tDCS is often determined by the electrode configuration and intensity of stimulation. MRI-derived finite element models have been developed to analyze the effect of these parameters allowing novel electrode configurations to be tested in subject specific models. By creating a subject specific model of an obese subject, the effect of fat on tDCS was examined. The inclusion of fat into the model led to an increase in cortical electric field intensity. To further investigate the influence of fat the conductivity was varied from that of skull to that of skin. Cortical electric field intensity did not change monotonically with fat conductivity. It was postulated that this may be due to a shunting effect both when the shell of fat surrounding the skull is too resistive for penetration and when the fat is so conductive as to lead current around rather than through the head. The effect of electrode positioning was then examined in a new 2x1 Hybrid montage utilizing both HD electrodes and sponge pads. Systematically varying the location of both the anode and cathode led to changes in the electric field distribution. This is in contrast to the old heuristic convention of placing the “active” electrode over a region of interest and neglecting the influence of the “return” electrode. Lastly the radial directionality of electric field was examined in a 4x1 ring configuration. Previous models have predicted the spatial focality of the 4x1 ring configuration. Polarity specificity, the ability to selectively apply either anodal or cathodal stimulation, was demonstrated in a 4x1 montage over the motor strip. The customization of models for specific populations and montages provides new avenues for clinical practice

Non-invasive brain stimulation as a novel approach to the treatment of chronic non-specific low back pain

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Chronic non-specific low back pain (CNSLBP) is a widespread but poorly understood condition that places a substantial burden on the sufferer, health services and the wider economy. Existing approaches to management do not demonstrate impressive levels of effectiveness. There is growing evidence that CNSLBP is associated with significant alterations in central nervous system (CNS) structure and function, suggesting a possible role for the brain in the aetiology of the condition, and presenting a case for novel therapies which aim to treat CNSLBP by affecting brain function. One such potential therapeutic approach is non-invasive brain stimulation (NIBS). Following a literature review discussing the epidemiology and management of low back pain, the evidence for altered CNS function and the potential role of brain stimulation in CNSLBP and chronic pain generally this thesis includes 3 original scientific studies: A Cochrane systematic review of the effectiveness of NIBS techniques for the treatment of chronic pain. A randomised double-blind exploratory study of transcranial direct current stimulation of the motor cortex in the treatment of CNSLBP Is blinding to the stimulation condition maintained in trials comparing 2mA tDCS with sham stimulation? A randomised cross-over study. RESULTS: There is limited existing evidence that some forms of NIBS may have a beneficial effect on chronic pain, though caution is warranted. Exploratory data from study 2 is not suggestive that tDCS to the motor cortex is effective for treating CNSLBP. Commonly used sham controls in trials of tDCS do not ensure adequate blinding, and so introduce a potential source of bias to the existing evidence base. CONCLUSION: Further research is required to establish the value of NIBS as a treatment for chronic pain and CNSLBP. Future research in tDCS will need to develop and employ fully validated sham controls to ensure adequate blinding. NIBS cannot currently be recommended for the treatment of CNSLBP.This study is partly funded by the BackCare UK and the Rosetrees Trust

Electroanalgesia: Historical and Contemporary Developments

Aims and Objectives: This thesis makes an in-depth examination of the historical, including the eighteenth-century pioneering electrical treatments of the Rev John Wesley, together with contemporary developments in electroanalgesia from the late twentieth-century, including the author's own pilot study, in order to provide a sound, scientific basis for their continuing use. The problem and the hypothesis: Controversy still surrounds the effectiveness of electrical treatments, even after 250 years of application. This is seen in its most researched form as TENS (transcutaneous electrical nerve stimulation) and ALTENS (acupuncture-like transcu taneous electrical nerve stimulation) for chronic back pain. The empirical research making up the main part of the thesis sets out to provide clear evidence to reject the null hypothesis, i.e. that there are no significant clinical effects from the use of electrical treatments for chronic back pain. Methods and findings: The empirical tertiary research centred on a systematic review and meta-analysis, within the framework of the Cochrane Collaboration, of all randomised controlled trials of TENS/ ALTENS for chronic back pain found during rigorous searches of the medical literature. Pooling their results in a meta-analysis established that effective clinical benefits are to be found in the use of ALTENS/TENS for chronic back pain, at least in the short term. Conclusions and recommendations: This wide ranging PhD thesis demonstrates for the first time significant clinical benefits of TENS/ ALTENS for treating patients with chronic back pain and if implemented on a global basis, then considerable numbers of chronic back pain sufferers could benefit

Walking aids for stroke patients

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International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020).

Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice