neurostimulation Dotaz Zobrazit nápovědu
Objective.The wireless transfer of power for driving implantable neural stimulation devices has garnered significant attention in the bioelectronics field. This study explores the potential of photovoltaic (PV) power transfer, utilizing tissue-penetrating deep-red light-a novel and promising approach that has received less attention compared to traditional induction or ultrasound techniques. Our objective is to critically assess key parameters for directly powering neurostimulation electrodes with PVs, converting light impulses into neurostimulation currents.Approach.We systematically investigate varying PV cell size, optional series configurations, and coupling with microelectrodes fabricated from a range of materials such as Pt, TiN, IrOx, Ti, W, PtOx, Au, or poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate). Additionally, two types of PVs, ultrathin organic PVs and monocrystalline silicon PVs, are compared. These combinations are employed to drive pairs of electrodes with different sizes and impedances. The readout method involves measuring electrolytic current using a straightforward amplifier circuit.Main results.Optimal PV selection is crucial, necessitating sufficiently large PV cells to generate the desired photocurrent. Arranging PVs in series is essential to produce the appropriate voltage for driving current across electrode/electrolyte impedances. By carefully choosing the PV arrangement and electrode type, it becomes possible to emulate electrical stimulation protocols in terms of charge and frequency. An important consideration is whether the circuit is photovoltage-limited or photocurrent-limited. High charge-injection capacity electrodes made from pseudo-faradaic materials impose a photocurrent limit, while more capacitive materials like Pt are photovoltage-limited. Although organic PVs exhibit lower efficiency than silicon PVs, in many practical scenarios, stimulation current is primarily limited by the electrodes rather than the PV driver, leading to potential parity between the two types.Significance.This study provides a foundational guide for designing a PV-powered neurostimulation circuit. The insights gained are applicable to bothin vitroandin vivoapplications, offering a resource to the neural engineering community.
- Klíčová slova
- bioelectronics, microelectrodes, neurostimulation, photovoltaics, wireless power transfer,
- MeSH
- design vybavení metody MeSH
- elektrická stimulace metody přístrojové vybavení MeSH
- implantabilní neurostimulátory MeSH
- implantované elektrody * MeSH
- mikroelektrody MeSH
- Publikační typ
- časopisecké články MeSH
Objective. Electric stimulation delivered by implantable electrodes is a key component of neural engineering. While factors affecting long-term stability, safety, and biocompatibility are a topic of continuous investigation, a widely-accepted principle is that charge injection should be reversible, with no net electrochemical products forming. We want to evaluate oxygen reduction reactions (ORR) occurring at different electrode materials when using established materials and stimulation protocols.Approach. As stimulation electrodes, we have tested platinum, gold, tungsten, nichrome, iridium oxide, titanium, titanium nitride, and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). We use cyclic voltammetry and voltage-step amperometry in oxygenated versus inert conditions to establish at which potentials ORR occurs, and the magnitudes of diffusion-limited ORR currents. We also benchmark the areal capacitance of each electrode material. We use amperometric probes (Clark-type electrodes) to quantify the O2and H2O2concentrations in the vicinity of the electrode surface. O2and H2O2concentrations are measured while applying DC current, or various biphasic charge-balanced pulses of amplitude in the range 10-30µC cm-2/phase. To corroborate experimental measurements, we employ finite element modelling to recreate 3D gradients of O2and H2O2.Main results. All electrode materials support ORR and can create hypoxic conditions near the electrode surface. We find that electrode materials differ significantly in their onset potentials for ORR, and in the extent to which they produce H2O2as a by-product. A key result is that typical charge-balanced biphasic pulse protocols do lead to irreversible ORR. Some electrodes induce severely hypoxic conditions, others additionally produce an accumulation of hydrogen peroxide into the mM range.Significance. Our findings highlight faradaic ORR as a critical consideration for neural interface devices and show that the established biphasic/charge-balanced approach does not prevent irreversible changes in O2concentrations. Hypoxia and H2O2can result in different (electro)physiological consequences.
- Klíčová slova
- bioelectronics, faradaic reactions, hypoxia, neurostimulation, reactive oxygen species,
- MeSH
- elektrická stimulace metody MeSH
- elektrody MeSH
- hypoxie MeSH
- implantované elektrody MeSH
- kyslík MeSH
- lidé MeSH
- peroxid vodíku * MeSH
- platina * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyslík MeSH
- peroxid vodíku * MeSH
- platina * MeSH
The main neuromodulatory methods using neurostimulation principles are described. It concerns peripheral nerve stimulation (PNS), spinal cord stimulation (SCS), deep brain stimulation (DBS), motor cortex stimulation (MSC), and repetitive transcranial magnetic stimulation (rTMS). For each method the history, pathophysiology, the principles for use and the associated diagnoses are mentioned. Special attention is focused on the most common neuromodulatory invasive methods like SCS and MCS and non-invasive methods such as rTMS. In addition to the positive effects, side effects and complications are described and discussed in detail. In conclusion, neuromodulatory (neurostimulatory) techniques are highly recommended for the treatment of different types of pharmacoresistant pain.
- MeSH
- biologické modely MeSH
- bolest patofyziologie MeSH
- chronická bolest terapie MeSH
- elektrostimulační terapie metody MeSH
- hluboká mozková stimulace metody MeSH
- lidé MeSH
- management bolesti metody MeSH
- motorické korové centrum patofyziologie MeSH
- mozek patofyziologie MeSH
- neuralgie patofyziologie terapie MeSH
- transkraniální magnetická stimulace metody MeSH
- transkutánní elektrická neurostimulace metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Although commonly seen in the clinical practice, chronic orofacial pain quite often does not have a clear unambiguous organic origin. It may be difficult to find optimal pharmacotherapy, and in many cases, this pain may become pharmacotherapy resistant. Neuromodulation, particularly with electromagnetic neurostimulation techniques, has been widely used for the treatment of different types of pharmacoresistant pain, and repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) exemplify readily available noninvasive neuromodulation methods. We have used rTMS and tDCS to treat pharmacoresistant chronic orofacial pain. rTMS uses an electromagnetic coil placed over the patient's head to induce electrical current impulses within the brain tissue, thereby modulating brain activity. In tDCS, an electrode placement location(s) must be chosen in accordance with the density and the time course of the current, mainly to prevent undesired pathological changes in the underlying tissue. Transcranial neuromodulation methods provide a nondestructive and reversible approach to treatment of severe and otherwise uncontrollable chronic orofacial pain. These methods may be curative - as a part of so called "reconstructive neurosurgery" stimulation of neural structures may be used as an alternative to surgical destruction of neural pathways.
- MeSH
- bránice patofyziologie MeSH
- elektrická stimulace MeSH
- hepatektomie MeSH
- lidé MeSH
- nádory jater komplikace chirurgie MeSH
- nádory rekta komplikace chirurgie MeSH
- nádory slinivky břišní komplikace chirurgie MeSH
- nervová blokáda metody MeSH
- nervus phrenicus diagnostické zobrazování fyziologie MeSH
- nezvladatelná bolest komplikace terapie MeSH
- pooperační komplikace terapie MeSH
- senioři MeSH
- škytavka etiologie terapie MeSH
- ultrasonografie MeSH
- umělé dýchání škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
Objective.This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus, and posterior hippocampus over an extended period.Approach.Impedance was periodically sampled every 5-15 min over several months in five subjects with drug-resistant epilepsy using an investigational neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24 h impedance cycle throughout the multi-month recording.Main results.Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 d to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24 h impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures.Significance.Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.
- Klíčová slova
- biological impedance, circadian cycle, epilepsy, implant effect, intracranial monitoring, neuromodulation,
- MeSH
- cizí tělesa * MeSH
- elektrická impedance MeSH
- hluboká mozková stimulace * metody MeSH
- implantované elektrody MeSH
- lidé MeSH
- mozek fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, N.I.H., Extramural MeSH
OBJECTIVE: This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus (AMG-HPC), and posterior hippocampus (post-HPC) over an extended period. APPROACH: Impedance was periodically sampled every 5-15 minutes over several months in five subjects with drug-resistant epilepsy using an experimental neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24-hour impedance cycle throughout the multi-month recording. MAIN RESULTS: Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 days to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24-hour impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures. SIGNIFICANCE: Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.
- Klíčová slova
- Biological impedance, Circadian cycle, Epilepsy, Implant effect, Intracranial monitoring, Neuromodulation,
- Publikační typ
- časopisecké články MeSH
- preprinty MeSH
AIM: The n. laryngeus recurrens (NLR) neurostimulation technique is described as a recently introduced method in the Czech Republic, used to prevent injuries to the recurrent nerve during thyroid procedures, highlighting its significance. METHOD: Neurostimulation of the n. laryngeus recurrens (NLR) during thyroid procedures is a method which has been, in recent years, introduced worldwide as a standard procedure in peroperative injuries prevention. A generally accepted doctrine on the risk of peroperative recurrent nerve lesions minimalization has not been established, however. neurostimulation may be a contribution. RESULTS: The new technique was employed in 370 patients operated in 2005/2006 and no permanent NLR paresis was recorded. CONCLUSION: Neurostimulation of the NLR during thyreoidectomy is a new method, further reducting probability of a peroperative recurrent nerve injury.
- MeSH
- elektrická stimulace přístrojové vybavení MeSH
- lidé MeSH
- nervus laryngeus recurrens fyziologie MeSH
- peroperační komplikace prevence a kontrola MeSH
- peroperační monitorování MeSH
- poranění nervus laryngeus recurrens * MeSH
- tyreoidektomie škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
Gastric dysmotility can be a sign of common diseases such as longstanding diabetes mellitus. It is known that the application of high-frequency low-energetic stimulation can help to effectively moderate and alleviate the symptoms of gastric dysmotility. The goal of our research was the development of a miniature, endoscopically implantable device to a submucosal pocket. The implantable device is a fully customized electronics package which was specifically designed for the purpose of experiments in the submucosa. The device was endoscopically inserted into the submucosal pocket of a pig stomach and partially severed pig side in order to adequately simulate a live animal model. The experiment confirmed that the designed device can be implanted into the submucosa and is capable of the measurement of sensor data and the transmission of this data wirelessly in real time to a computer outside of the body. After proving that the device can be implanted submucosally and transmit data, further experiments can now be performed, primarily with an electrogastrography (EGG) instrument and implantable device with tissue stimulation capability.
- Publikační typ
- časopisecké články MeSH
BACKGROUND: There are no head-to-head studies comparing the antidepressant effect of transcranial direct current stimulation (tDCS) with repetitive transcranial magnetic stimulation (rTMS). This pooled analysis compared indirectly the antidepressant efficacy and acceptability of rTMS, tDCS, and the antidepressant venlafaxine (VNF) extended-release. METHODS: The analysis (n=117, both patients with treatment-resistant depression (TRD) and non-TRD were included) examined pooled data from two 4-week, single-centered, two-armed, double-blind, randomized studies (EUDRACT n. 2005-000826-22 and EUDRACT n. 2015-001639-19). The antidepressant efficacy of right-sided low-frequency rTMS (n=29) vs VNF (n=31) and left-sided anodal tDCS (n=29) vs VNF (n=28) was evaluated. The primary outcome was a change in the Montgomery-Åsberg Depression Rating Scale (MADRS) score from baseline to the treatment endpoint at week 4. The response was defined as a ≥50% reduction in the MADRS score and remission as the MADRS score ≤10 points, both were calculated for the primary treatment endpoint at week 4. RESULTS: Mean change in total MADRS scores from baseline to week 4 was 7.0 (95% CI, 4.8-9.1) points in the rTMS group, 7.6 (95% CI, 5.5-9.8) in the tDCS group, and 8.9 (95% CI, 7.4-10.4) among patients in the VNF group, a non-significant difference (F(2111)=0.62, p=0.54). Similarly, neither the response rates nor remission rates for rTMS (response 31%; remission 17%), tDCS (24%, 17%), or VNF (41%; 27%) significantly differed among treatment groups (χ 2=2.59, p=0.28; χ 2=1.66, p=0.44). Twenty patients (17%) dropped out of the studies in a similar proportion across groups (rTMS 3/29, tDCS 6/29, VNF 11/59, χ 2=1.41, p=0.52). CONCLUSION: Our current analysis found a comparable efficacy and acceptability in all three treatment modalities (rTMS, tDCS, and VNF) and clinical relevance for the acute treatment of major depressive disorder.
- Klíčová slova
- MDD, efficacy, major depressive disorder, rTMS, repetitive transcranial magnetic stimulation, tDCS, transcranial direct-current stimulation, treatment, venlafaxine,
- Publikační typ
- časopisecké články MeSH
