Electrode Position Research Articles

Hybrid Deep Brain Stimulation for Parkinson’s Disease and Dystonia Improves Side Effects, Maintaining Clinical Benefit

Introduction: Deep brain stimulation (DBS) in movement disorders does not always achieve optimal symptomatic control. Most common issues involve suboptimal electrode positioning and target stimulation and troublesome side effects limiting the therapeutic window. Recently approved implantable pulse generators (IPG) allow for pulse widths lower than 60 μs, increasing the therapeutic window, and current steering. These new constant-current IPG (CC-IPG), in addition to these characteristics, have rechargeable, thus longer duration, batteries. This work aims to describe a tertiary center’s experience with replacing a constant-voltage stimulation non-rechargeable implantable pulse generator (CV-IPG), at the end of its battery’s lifespan, with a CC-IPG, with more options in pulse duration changes and multiplesource current steering. Methods: A retrospective review of the clinical records of patients submitted to DBS who had their CV-IPG replaced with CC-IPG was performed, documenting reason for preference, stimulation parameters, clinical benefit pre and post-replacement and side effects. Results: Six patients who fulfilled the criteria were identified, four with Parkinson’s disease (PD) and two with dystonia. The reasons for preference were: stimulation side effects (2), suboptimal benefit (1), long battery duration (3). Side effects were improved by using a 30 μs pulse in two patients. Current steering allowed the shortening of OFF periods in 1 PD patient. One patient with dystonia had initial decrease in clinical benefit but recovered after amplitude correction according to impedance. The other two patients remained stable post-replacement. Conclusion: Replacement of CV-IPG with CC-IPG proved feasible and safe, with non-inferior clinical benefit, additionally providing pulse lowering and current steering strategies for solving suboptimal results with DBS.

Vagus nerve stimulation using an endovascular electrode array

Objective. Vagus nerve stimulation (VNS), which involves a surgical procedure to place electrodes directly on the vagus nerve (VN), is approved clinically for the treatment of epilepsy, depression, and to facilitate rehabilitation in stroke. VNS at surgically implanted electrodes is often limited by activation of motor nerve fibers near and within the VN that cause neck muscle contraction. In this study we investigated endovascular VNS that may allow activation of the VN at locations where the motor nerve fibers are not localized. Approach. We used endovascular electrodes within the nearby internal jugular vein (IJV) to electrically stimulate the VN while recording VN compound action potentials (CAPs) and neck muscle motor evoked potentials (MEPs) in an acute intraoperative swine experiment. Main Results. We show that the stimulation electrode position within the IJV is critical for efficient activation of the VN. We also demonstrate use of fluoroscopy (cone beam CT mode) and ultrasound to determine the position of the endovascular stimulation electrode with respect to the VN and IJV. At the most effective endovascular stimulation locations tested, thresholds for VN activation were several times higher than direct stimulation of the nerve using a cuff electrode; however, this work demonstrates the feasibility of VNS with endovascular electrodes and provides tools to optimize endovascular electrode positions for VNS. Significance. This work lays the foundation to develop endovascular VNS strategies to stimulate at VN locations that would be otherwise too invasive and at VN locations where structures such as motor nerve fibers do not exist.

Do emotions conquer facts? A CCME model for the impact of emotional information on implicit attitudes in the post-truth era

This study aimed to examine the influence of emotional media information on information-processing mechanisms in the current post-truth era. A cognitive conflict monitoring and evaluation (CCME) model was proposed to explore news audiences’ attention and implicit attitudes. The study had a 2 (information type, emotional vs. neutral) × 2 (condition, compatible vs. incompatible) × 3 (electrode position: Fz vs. Cz vs. Pz) design, and an implicit association test (IAT) was administered, with event-related potential (ERP) data collected. The results revealed that emotional information evoked different information-processing mechanisms than neutral information. First, in the early conflict-monitoring stage, emotional information altered arousal, and more attentional resources were allocated to semantic processing. Second, in the late evaluation stage, the lack of attentional resources (due to prior allocation) reduced the late-stage evaluation of the target stimuli by participants. Thus, in this post-truth era, attentional resources may be exhausted by processing emotional information in unnecessary media cues irrelevant to facts, inducing early cognitive conflict and prolonged late-stage evaluation of news articles.

Creation of a training and test dataset with the disposition and transposition of overlaying electrocardiographic electrodes when recording electrocardiograms-12

BACKGROUND: Electrocardiography is one of the simplest, most widely used, inexpensive, and informative methods in functional diagnostics; yet, if performed poorly, its diagnostic value is sharply reduced. Several attempts were made to systematize errors and deviations in electrode application, but all concerned the most common options (rearrangement of red and yellow electrodes, yellow and green electrodes, and chest electrodes above or below the standard scheme).
 AIM: To create an electrocardiogram dataset with different options for transpositions and dispositions of electrodes during electrocardiogram recording.
 MATERIALS AND METHODS: The study included patients aged 1875 years (27 males and 22 females). All patients provided informed consent for electrocardiogram registration. During one visit, the cardiogram was recorded on the device Modular system for recording and remote transmission of electrocardiograms (EASY ECG) for each patient.
 RESULTS: In all, 488 electrocardiograms were recorded in 49 patients. The results obtained indicate a significant variability of the electrocardiogram pattern. Visual analysis of the electrocardiograms revealed no difficulties in determining the transposition associated with rearranging the leads on the arms (RY) in the thoracic C1C2. The placement of thoracic electrodes in contact cheek-to-cheek dispositions with the transfer of thoracic leads above or below two intercostals was reliably determined compared with the Wilson scheme. The transpositions of the yellow and green limb electrodes and the change in the position of the thoracic ones when they are lined up in a straight line, bullied between the ribs (curved), and confused in places C5 and C6 are difficult to determine even when comparing two cardiograms next to each other, with the correct and transpositional superposition of the electrodes. The initial changes on the electrocardiograms, physique type, breast size, or the presence of an implant most likely determine it.
 CONCLUSION: An electrocardiography dataset was obtained using various electrode dislocation variants. The dataset consists of a series of electrocardiograms obtained for each patient with several electrode placement options and contains both normal and pathological electrocardiograms.

Evaluation of Time-Dependent Corrosion Inhibition Rate for f-MWCNT-BCP Composite Coatings on 316L Stainless Steel in Simulated Body Fluid for Orthopedic Implantation.

A well-developed-multiwall carbon nanotube (f-MWCNT)/biphasic calcium phosphate (BCP) composites were synthesized using ultrasonication method for orthopedic implantation applications. The formation of composites and its phase was confirmed by using X-ray diffraction. The presence of various functional groups was identified by using Fourier transform infra-red (FT-IR) spectroscopy. The presence of f-MWCNT was confirmed by Raman spectroscopy. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that BCP units were bound by the surface of f-MWCNTs. The synthesized composites were coated on medical grade 316L stainless steel substrates using electro deposition technique. To determine its corrosion resistance characteristics, the developed substrates were exposed to a simulated bodily fluid (SBF) solution for 0, 4, and 7days. These results strongly suggest that the coated composites can be utilized for bone tissue repair.

Development of a Sham Protocol to Investigate Transcutaneous Tibial Nerve Stimulation in Randomised, Sham-Controlled, Double-Blind Clinical Trials.

Transcutaneous tibial nerve stimulation (TTNS) is a promising treatment for neurogenic lower urinary tract symptoms. However, the evidence is limited due to a general lack of randomised controlled trials (RCTs) and, also, inconsistency in the sham and blinding conditions. In the context of much-needed RCTs, we aimed to develop a suitable sham-control protocol for a clinical setting to maintain blinding but avoid meaningful stimulation of the tibial nerve. Three potential electrode positions (lateral malleolus/5th metatarsal/plantar calcaneus) and two electrode sizes (diameter: 2.5 cm/3.2 cm) were tested to determine which combination provided the optimal sham configuration for a TTNS approach, based on a visible motor response. Sixteen healthy volunteers underwent sensory and motor assessments for each sham configuration. Eight out of them came back for an extra TTNS visit. Sensory thresholds were present for all sham configurations, with linear regression models revealing a significant effect regarding electrode position (highest at plantar calcaneus) but not size. In addition, motor thresholds varied with the position-lowest for the 5th metatarsal. Only using this position and 3.2 cm electrodes attained a 100% response rate. Compared to TTNS, sensory and motor thresholds were generally higher for the sham configurations; meanwhile, perceived pain was only higher at the lateral malleolus. In conclusion, using the 5th metatarsal position and 3.2 cm electrodes proved to be the most suitable sham configuration. Implemented as a four-electrode setup with standardized procedures, this appears to be a suitable RCT protocol for maintaining blinding and controlling for nonspecific TTNS effects in a clinical setting.

OPTIMAL LOCATION OF ACTION POTENTIAL GENERATION BASED ON ACTIVATION FUNCTION USING COMPUTATIONAL MODELLING

Transcutaneous electrical nerve stimulation is used to elevate health-related disorders. This technology is now an important therapeutic system for medical science. In this system, the electrical current pulse is applied over the skin through the inner layers via electrodes to activate excitable tissue layers. Activating other excitable tissue layers may cause discomfort. Thus, it is vital to design electrode configuration arrangements to activate the target anatomical layers without affecting the neighboring ones. A device for primary headaches showed mixed results. This may be related to the electrode position that requires higher stimulus current levels to activate target nerve fibers. This may stimulate neighboring nerve fibers which resulted in the discomfort of patients. A feasible solution is to identify the optimal electrode configuration based on the activation function which is the second derivative of the electric potential along an axon. This may guide to estimate of the possibility of action potential generation on the neural tissue layer using a specified electrode arrangement. In this study, the multilayered human head was developed based on MRI data set using pre and post-processing. Then multi-electrode arrangements were developed to examine the possible nerve activation location. Results showed that the nerve fibers were activated at the same location of the trajectory for the anodal and cathodal stimulation. This may be proof that the activation function can be used to define the optimal location of nerve activation. This may lead to lower thresholds for similar therapeutic benefits in transcutaneous electrical nerve stimulation with decreased power consumption.

Body surface potential mapping detects early disease onset in plakophilin-2-pathogenic variant carriers.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive inherited cardiac disease. Early detection of disease and risk stratification remain challenging due to heterogeneous phenotypic expression. The standard configuration of the 12 lead electrocardiogram (ECG) might be insensitive to identify subtle ECG abnormalities. We hypothesized that body surface potential mapping (BSPM) may be more sensitive to detect subtle ECG abnormalities. We obtained 67 electrode BSPM in plakophilin-2 (PKP2)-pathogenic variant carriers and control subjects. Subject-specific computed tomography/magnetic resonance imaging based models of the heart/torso and electrode positions were created. Cardiac activation and recovery patterns were visualized with QRS- and STT-isopotential map series on subject-specific geometries to relate QRS-/STT-patterns to cardiac anatomy and electrode positions. To detect early signs of functional/structural heart disease, we also obtained right ventricular (RV) echocardiographic deformation imaging. Body surface potential mapping was obtained in 25 controls and 42 PKP2-pathogenic variant carriers. We identified five distinct abnormal QRS-patterns and four distinct abnormal STT-patterns in the isopotential map series of 31/42 variant carriers. Of these 31 variant carriers, 17 showed no depolarization or repolarization abnormalities in the 12 lead ECG. Of the 19 pre-clinical variant carriers, 12 had normal RV-deformation patterns, while 7/12 showed abnormal QRS- and/or STT-patterns. Assessing depolarization and repolarization by BSPM may help in the quest for early detection of disease in variant carriers since abnormal QRS- and/or STT-patterns were found in variant carriers with a normal 12 lead ECG. Because electrical abnormalities were observed in subjects with normal RV-deformation patterns, we hypothesize that electrical abnormalities develop prior to functional/structural abnormalities in ARVC.

Machine versus physician-based programming of deep brain stimulation in isolated dystonia: A feasibility study

BackgroundDeep brain stimulation of the internal globus pallidus effectively alleviates dystonia motor symptoms. However, delayed symptom control and a lack of therapeutic biomarkers and a single pallidal sweetspot region complicates optimal programming. Postoperative management is complex, typically requiring multiple, lengthy follow-ups with an experienced physician – an important barrier to widespread adoption in medication-refractory dystonia patients. ObjectiveHere we prospectively tested the best machine-predicted programming settings in a dystonia cohort treated with GPi-DBS against the settings derived from clinical long-term care in a specialised DBS centre. MethodsPreviously, we reconstructed an anatomical map of motor improvement probability across the pallidal region using individual stimulation volumes and clinical outcomes in dystonia patients. We used this to develop an algorithm that tests in silico thousands of putative stimulation settings in de novo patients after reconstructing an individual, image-based anatomical model of electrode positions, and suggests stimulation parameters with the highest likelihood of optimal symptom control. To test real-life application, our prospective study compared results in 10 patients against programming settings derived from long-term care. ResultsIn this cohort, dystonia symptom reduction was observed at 74.9 ± 15.3% with C-SURF programming as compared to 66.3 ± 16.3% with clinical programming (p < 0.012). The average total electrical energy delivered (TEED) was similar for both the clinical and C-SURF programming (262.0 μJ/s vs. 306.1 μJ/s respectively). ConclusionOur findings highlight the clinical potential of machine-based programming in dystonia, which could markedly reduce the programming burden in postoperative management.

Alpha-Theta Correlations during the Different States of the Brain for a Designed Cognitive Task

Brain oscillations vary due to neurological activities that play an important role in designing a cognitive task. In the proposed study, 27 subjects experimented with different cognitive activities (rest, meditation, and arithmetic) and their alpha and theta bands of frequencies were analyzed. BIOPAC-MP-160 has performed the data acquisition and further processing of the acquired dataset was implemented in EEGLAB. The results illustrated that the cross-frequency correlation (alpha: theta: 1:2) between alpha and theta waves has been enhanced during effortful cognition (arithmetic state). The alpha-theta cross-frequencies were observed to be maximum in the arithmetic state, while it remains low in both the resting and meditation states. Maximum episodes of the cross-frequency correlations occurred when the alpha band of frequencies lies between 9-12 Hz. The study also reveals that maximum alpha-theta cross-frequency (40.74%) was found at the electrode positions Af3 and Af4. The comparisons based on event-related potentials (ERPs) and power spectral densities (PSDs) have shown that the meditation state is more sluggish than the arithmetic and rest states.

Evaluating the influence of anatomical accuracy and electrode positions on EEG forward solutions

Generating realistic volume conductor models for forward calculations in electroencephalography (EEG) is not trivial and several factors contribute to the accuracy of such models, two of which are its anatomical accuracy and the accuracy with which electrode positions are known. Here, we investigate effects of anatomical accuracy by comparing forward solutions from SimNIBS, a tool which allows state-of-the-art anatomical modeling, with well-established pipelines in MNE-Python and FieldTrip. We also compare different ways of specifying electrode locations when digitized positions are not available such as transformation of measured positions from standard space and transformation of a manufacturer layout.Substantial effects of anatomical accuracy were seen throughout the entire brain both in terms of field topography and magnitude with SimNIBS generally being more accurate than the pipelines in MNE-Python and FieldTrip. Topographic and magnitude effects were particularly pronounced for MNE-Python which uses a three-layer boundary element method (BEM) model. We attribute these mainly to the coarse representation of the anatomy used in this model, in particular differences in skull and cerebrospinal fluid (CSF). Effects of electrode specification method were evident in occipital and posterior areas when using a transformed manufacturer layout whereas transforming measured positions from standard space generally resulted in smaller errors.We suggest modeling the anatomy of the volume conductor as accurately possible and we hope to facilitate this by making it easy to export simulations from SimNIBS to MNE-Python and FieldTrip for further analysis. Likewise, if digitized electrode positions are not available, a set of measured positions on a standard head template may be preferable to those specified by the manufacturer.

Quantifying the Variability Associated with Postoperative Localization of Deep Brain Stimulation Electrodes

Introduction: Computational models of deep brain stimulation (DBS) have become common tools in clinical research studies that attempt to establish correlations between stimulation locations in the brain and behavioral outcome measures. However, the accuracy of any patient-specific DBS model depends heavily upon accurate localization of the DBS electrodes within the anatomy, which is typically defined via co-registration of clinical CT and MRI datasets. Several different approaches exist for this challenging registration problem, and each approach will result in a slightly different electrode localization. The goal of this study was to better understand how different processing steps (e.g., cost-function masking, brain extraction, intensity remapping) affect the estimate of the DBS electrode location in the brain. Methods: No “gold standard” exists for this kind of analysis, as the exact location of the electrode in the living human brain cannot be determined with existing clinical imaging approaches. However, we can estimate the uncertainty associated with the electrode position, which can be used to guide statistical analyses in DBS mapping studies. Therefore, we used high-quality clinical datasets from 10 subthalamic DBS subjects and co-registered their long-term postoperative CT with their preoperative surgical targeting MRI using 9 different approaches. The distances separating all of the electrode location estimates were calculated for each subject. Results: On average, electrodes were located within a median distance of 0.57 mm (0.49–0.74) of one another across the different registration approaches. However, when considering electrode location estimates from short-term postoperative CTs, the median distance increased to 2.01 mm (1.55–2.78). Conclusions: The results of this study suggest that electrode location uncertainty needs to be factored into statistical analyses that attempt to define correlations between stimulation locations and clinical outcomes.

Optimizing surface properties of Ti13Nb13Zr alloy substrate for biomedical applications through modification with nano-alumina obtained by atomic layer deposition and hydroxyapatite coatings

Ti13Nb13Zr (TNZ) alloys have attracted the interest of researchers as viable and controllable alternatives for biometrics. The research on bioactive coatings of metal alloys has contributed to successful bone therapy by accelerating the osseointegration process. In this context, we present a study on the surface modifications of the TNZ alloy substrate ultrafine-grained (UFG) by severe plastic deformation using high-pressure torsion. Nano-Al2O3 coatings by atomic layer deposition (ALD) and low-temperature hydroxyapatite by electrodeposition (EDP) and simulated body fluid (SBF) were used. We also investigated the cytotoxicity of all surface modifications obtained up to 72 h on osteoblasts. An alumina film was obtained by thermal ALD at 150 °C (nano-Al2O3-TNZ) to enhance the deposition of HAp on the nanostructured substrate obtained by EDP (HAp1-Al2O3-TNZ) and SBF (HAp2-Al2O3-TNZ). The results of the coating processes were analyzed by different techniques such as AFM, SEM, XRD, EDS, and Raman spectroscopy. The coated HAp1-Al2O3-TNZ and HAp2-Al2O3-TNZ samples showed dense and uniform bilayer surface formation. We noticed that surface modification directly influenced the roughness of the TNZ sample independently of the method used. Our surface modification of the TNZ alloy using ALD and HAp from two applied methods showed no cytotoxicity and increased cell proliferation. Therefore, these surface modifications represent a strategy for obtaining a bioactive alloy that can be used as a bone implant.

Closed-loop parameter optimization for patient-specific phrenic nerve stimulation.

Ventilator-induced diaphragm dysfunction occurs rapidly following the onset of mechanical ventilation and has significant clinical consequences. Phrenic nerve stimulation has shown promise in maintaining diaphragm function by inducing diaphragm contractions. Non-invasive stimulation is an attractive option as it minimizes the procedural risks associated with invasive approaches. However, this method is limited by sensitivity to electrode position and inter-individual variability in stimulation thresholds. This makes clinical application challenging due to potentially time-consuming calibration processes to achieve reliable stimulation. We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. A closed-loop system recorded the respiratory flow produced by stimulation and automatically adjusted the electrode position and stimulation amplitude based on the respiratory response. By iterating over electrodes, the optimal electrode was selected. A binary search method over stimulation amplitudes was then employed to determine an individualized stimulation threshold. Pulse trains above this threshold were delivered to produce diaphragm contraction. Nine healthy volunteers were recruited. Mean threshold stimulation amplitude was 36.17 ± 14.34 mA (range 19.38-59.06 mA). The threshold amplitude for reliable nerve capture was moderately correlated with BMI (Pearson's r = 0.66, p = 0.049). Repeating threshold measurements within subjects demonstrated low intra-subject variability of 2.15 ± 1.61 mA between maximum and minimum thresholds on repeated trials. Bilateral stimulation with individually optimized parameters generated reliable diaphragm contraction, resulting in significant inhaled volumes following stimulation. We demonstrate the feasibility of a system for automatic optimization of electrode position and stimulation parameters using a closed-loop system. This opens the possibility of easily deployable individualized stimulation in the intensive care setting to reduce ventilator-induced diaphragm dysfunction.

ECG Electrode Localization: 3D DS Camera System for Use in Diverse Clinical Environments

Models of the human body representing digital twins of patients have attracted increasing interest in clinical research for the delivery of personalized diagnoses and treatments to patients. For example, noninvasive cardiac imaging models are used to localize the origin of cardiac arrhythmias and myocardial infarctions. The precise knowledge of a few hundred electrocardiogram (ECG) electrode positions is essential for their diagnostic value. Smaller positional errors are obtained when extracting the sensor positions, along with the anatomical information, for example, from X-ray Computed Tomography (CT) slices. Alternatively, the amount of ionizing radiation the patient is exposed to can be reduced by manually pointing a magnetic digitizer probe one by one to each sensor. An experienced user requires at least 15 min. to perform a precise measurement. Therefore, a 3D depth-sensing camera system was developed that can be operated under adverse lighting conditions and limited space, as encountered in clinical settings. The camera was used to record the positions of 67 electrodes attached to a patient’s chest. These deviate, on average, by 2.0 mm ±1.5 mm from manually placed markers on the individual 3D views. This demonstrates that the system provides reasonable positional precision even when operated within clinical environments.

Spatiotemporal phase slip patterns for visual evoked potentials, covert object naming tasks, and insight moments extracted from 256 channel EEG recordings.

Phase slips arise from state transitions of the coordinated activity of cortical neurons which can be extracted from the EEG data. The phase slip rates (PSRs) were studied from the high-density (256 channel) EEG data, sampled at 16.384 kHz, of five adult subjects during covert visual object naming tasks. Artifact-free data from 29 trials were averaged for each subject. The analysis was performed to look for phase slips in the theta (4-7 Hz), alpha (7-12 Hz), beta (12-30 Hz), and low gamma (30-49 Hz) bands. The phase was calculated with the Hilbert transform, then unwrapped and detrended to look for phase slip rates in a 1.0 ms wide stepping window with a step size of 0.06 ms. The spatiotemporal plots of the PSRs were made by using a montage layout of 256 equidistant electrode positions. The spatiotemporal profiles of EEG and PSRs during the stimulus and the first second of the post-stimulus period were examined in detail to study the visual evoked potentials and different stages of visual object recognition in the visual, language, and memory areas. It was found that the activity areas of PSRs were different as compared with EEG activity areas during the stimulus and post-stimulus periods. Different stages of the insight moments during the covert object naming tasks were examined from PSRs and it was found to be about 512 ± 21 ms for the 'Eureka' moment. Overall, these results indicate that information about the cortical phase transitions can be derived from the measured EEG data and can be used in a complementary fashion to study the cognitive behavior of the brain.

Magnetic Manipulation of Locomotive Liquid Electrodes for Wireless Active Cardiac Monitoring.

For electrocardiogram (ECG) detection, the position of conventional patch-type electrodes based on solid-state metals are difficult to manipulate after attachment and also can lead to poor interface with stretchable, rough skin surfaces. Herein, we present a liquid form of ECG electrodes that can be magnetically reconfigured on human skin by providing its conformal interfacing. These electrodes consist of biocompatible liquid-metal droplets where magnetic particles are homogeneously dispersed, and their conformal contact with skin can yield significantly low impedance as well as high signal-to-noise ratio of ECG peaks. These electrodes are also capable of complex motions such as linear movements, splitting, and merging under external magnetic fields. Furthermore, magnetic manipulation of each electrode position on human skin enables precise monitoring of ECG signals with the change in ECG vectors. The integration of liquid-state electrodes with electronic circuitry demonstrates wireless and continuous ECG monitoring while magnetically moving this entire system on human skin.

ID: 212051 EM Exposure During Non-Invasive Brain Stimulation Applications: Impact of Uncertainties on Treatment Relevant Metrics

Performance and safety of non-invasive brain stimulation (NIBS) techniques (e.g., transcranial electric stimulation (tES) or temporal interference stimulation (TIS)) rely on the precise delivery of stimulation dose (typically electric (E-)field related quantities) to targets. The assessment of uncertainty associated with electromagnetic (EM) dose calculated by finite-element method (FEM) simulations using detailed anatomical human head models to optimize stimulation parameters (e.g., electrode positions, current intensities) and predict safety and performance metrics is therefore essential. We systematically investigated the impact of experimental and modelling sources of uncertainty/variability on tES exposure and exposure-derived quantities (maximum amplitude modulation for TIS, focality of stimulation, etc.).

Localization of the gracilis muscle motor points - key considerations for botulinum neurotoxin injection and electrical stimulation.

Muscle motor points are considered the best sites for electrode positioning in electrical stimulation and, by some researchers, for botulinum neurotoxin injections. The aim of this study is to locate the motor points in the gracilis muscle to improve muscle function maintenance and treatment of spasticity. Ninety-three gracilis muscles (49 right, 44 left), fixed in 10% formalin solution, were subjected to the research. All nerve branches running towards the muscle were precisely traced to each motor point. Specific measurements were collected. The gracilis muscle presents multiple motor points (median of 12), all of which were localized on the deep (lateral) side of the muscle belly. Generally, motor points of this muscle were spread between 15% - 40% of the reference line length. Our findings may help clinicians identify appropriate locations for electrode placement during electrical stimulation of the gracilis muscle; they also deepen our understanding of the correlation between motor points and motor end plates and improve the application of botulinum neurotoxin injections.

Very high-power short-duration pulmonary vein isolation combined with anterior chest position of dispersive electrodes

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Pulmonary vein isolation (PVI) is a cornerstone management of atrial fibrillation (AF). Very high-power short-duration (vHPSD) radiofrequency catheter ablation (RFCA) can accelerate PVI procedure. Recently, special attention has been paid to the position of dispersive electrodes (DE) for optimization of RFCA application. However, these two methods have not yet been combined in the setting of PVI. Purpose To determine feasibility, safety, efficacy, and overall performance of vHPSD PVI with anterior chest position of DE. Methods Consecutive patients undergoing vHPSD PVI using flexible-tip catheter and anterior position of DE were included in the study. vHPSD protocol consisted of 70W RFCA applications lasting 4s. If needed, RFCA applications were extended using 50W until R-positive unipolar signal modification and/or until impedance drop ≥10% from baseline was achieved or were terminated in case of steam-pop occurrence. Demographical, clinical, procedural and follow-up data were collected. Results A total number of 43 patients (25 males, age 61±14years) were included in the study. 34 patients had paroxysmal AF (parox-AF group) and 9 patients had persistent AF (pers-AF group). Mean procedure time was 61±7min, mean RFCA time was 685±204s. All PVs were successfully isolated. Audible steam pops without sequele occurred in 6 (14%) cases. Major complications included one TIA without sequele. During follow-up 33 (77%) patients remained AF-free: 26 (76%) in parox-AF group vs 7 (78%) in pers-AF group (log rank p=0.0166). No atrioesophageal fistula or evidence of esophageal injury occurred. Conclusions Anterior chest position of DE combined with vHPSD approach for PVI is feasible, appears safe and effective. More data on possible protective properties against atrioesophageal fistula occurrence using the presented approach is warranted.