HDE-Array: Development and Validation of a New Dry Electrode Array Design to Acquire HD-sEMG for Hand Position Estimation.

This paper aims to introduce HDE-Array (High-Density Electrode Array), a novel dry electrode array for acquiring High-Density surface electromyography (HD-sEMG) for hand position estimation through RPC-Net (Recursive Prosthetic Control Network), a neural network defined in a previous study. We aim to demonstrate the hypothesis that the position estimates returned by RPC-Net using HD-sEMG signals acquired with HDE-Array are as accurate as those obtained from signals acquired with gel electrodes. We compared the results, in terms of precision of hand position estimation by RPC-Net, using signals acquired by traditional gel electrodes and by HDE-Array. As additional validation, we performed a variance analysis to confirm that the presence of only two rows of electrodes does not result in an excessive loss of information, and we characterized the electrode-skin impedance to assess the effects of the voltage divider effect and power line interference. Performance tests indicated that RPC-Net, used with HDE-Array, achieved comparable or superior results to those observed when used with the gel electrode setup. The dry electrodes demonstrated effective performance even with a simplified setup, highlighting potential cost and usability benefits. These results suggest improvements in the accessibility and user-friendliness of upper-limb rehabilitation devices and underscore the potential of HDE-Array and RPC-Net to revolutionize control for medical and non-medical applications.

Phonons reveal coupled cholesterol-lipid dynamics in ternary membranes.

Experimental studies of collective dynamics in lipid bilayers have been challenging due to the energy resolution required to observe these low-energy phonon-like modes. However, inelastic X-ray scattering (IXS) measurements - a technique for probing vibrations in soft and biological materials - are now possible with sub-meV resolution, permitting direct observation of low energy, phonon-like modes in lipid membranes. Here, IXS measurements with sub-meV energy resolution reveal a low-energy optic-like phonon mode at roughly 3 meV in the liquid-ordered (Lo) and liquid-disordered (Ld) phases of a ternary lipid mixture. This mode is only observed experimentally at momentum transfers greater than 5 nm-1 in the (Lo) system. A similar gapped mode is also observed in all-atom molecular dynamics (MD) simulations of the same mixture, indicating that the simulations accurately represnt the fast, collective dynamics in the (Lo) phase. It's optical nature and the Q range of the gap together suggest that the observed mode is due to the coupled motion of cholesterol-lipid pairs, separated by several hydrocarbon chains within the membrane plane. Analysis of the simulations provide molecular insight into the origin of the mode in transient, nanoscale substructures of hexagonally packed hydrocarbon chains. This nanoscale hexagonal packing was previously reported based on molecular dynamics simulations and later by NMR measurements. Here, however, the integration of IXS and MD simulations identifies a new signature of the L° substructure in the collective lipid dynamics, thanks to the recent confluence of IXS sensitivity and MD simulation capabilities.

Deep brain stimulation of the motor thalamus relieves experimentally induced air hunger.

RESEARCH QUESTION: We previously reported that Deep Brain Stimulation (DBS) of motor thalamus (MT), in a patient with post-stroke tremor, relieved breathlessness associated with chronic obstructive pulmonary disease. This raised the question of whether MT DBS mitigates the ascending dyspnoea signal. We therefore sought to conduct a fully powered cohort study of experimentally induced air hunger (AH), an uncomfortable urge to breathe in patients with MT DBS ON and OFF. METHODS: 16 patients (3 females) with DBS of the ventral intermediate nucleus (VIM) as treatment for tremor, underwent hypercapnic AH tests, with DBS "ON" and "OFF". Patients rated AH on a visual analogue scale (VAS) every 15 s. Hypercapnia and ventilation were matched for ON and OFF states (mean±sd 43±4 and 43±4 mmHg for end-tidal PCO2, 13.7 and 13.4 L·min-1 for ventilation). Participants ventilation was constrained to baseline levels by breathing from a 3-litre inspiratory reservoir with fixed flow of fresh gas while targeting their resting breathing frequency to a metronome. RESULTS: Overall steady state AH was 52±28%VAS for "ON" and 67±20%VAS for "OFF" (p=0.002; two-tailed paired t-test). The mean reduction in AH during VIM DBS was -14.4%VAS. MT DBS relieved AH in thirteen patients, heightened AH in two and caused no change in one. CONCLUSION: MT DBS for tremor relief also mitigates the AH component of dyspnoea. We posit that DBS of the MT heightens the gating control of the thalamus modulating the ascending air hunger signal. Extent of relief suggests that thalamic DBS may prove to be a viable therapy for intractable dyspnoea.

Empowering Medical Students to Address Patient-Initiated Mistreatment at the Transition to Residency: An Education Quality Improvement Study.

BACKGROUND: Mistreatment from patients is prevalent and has far-reaching negative consequences. AIM: To develop a practice-based curriculum on patient-initiated mistreatment and examine participant perceptions before and after the curriculum. SETTING: Single medical school in the United States. PARTICIPANTS: 306 senior medical students from classes 2022 and 2023. PROGRAM DESCRIPTION: A single patient-initiated mistreatment session delivered during specialty-specific residency preparation courses (RPCs) featuring a literature discussion, a response framework, and patient-actor skills practice. PROGRAM EVALUATION: Between February 2022 and October 2023, 22 sessions occurred. Electronic surveys were delivered before, following, and approximately eight months after each session. A total of 257 (84.0%) and 174 (56.9%) participants completed pre- and post-session surveys, respectively. Significant increases in mean scores were noted for confidence in recognizing mistreatment (pre-session 4.25, post-session 4.68; p < 0.001) and comfort in addressing mistreatment personally (pre-session 2.86, post-session 4.30; p < 0.001) and as a bystander (pre-session 2.98, post-session 4.27; p < 0.001). In the follow-up survey, participants noted that the session was useful in preparing them for residency. DISCUSSION: A novel patient-initiated mistreatment curriculum empowered students, resulting in enhanced confidence in responding and sustained skill usage. Medical schools may consider including this training for all graduating students.

Opportunities to Improve Communication With Residency Applicants: Cross-Sectional Study of Obstetrics and Gynecology Residency Program Websites.

Background: As part of the residency application process in the United States, many medical specialties now offer applicants the opportunity to send program signals that indicate high interest to a limited number of residency programs. To determine which residency programs to apply to, and which programs to send signals to, applicants need accurate information to determine which programs align with their future training goals. Most applicants use a program's website to review program characteristics and criteria, so describing the current state of residency program websites can inform programs of best practices. Objective: This study aims to characterize information available on obstetrics and gynecology residency program websites and to determine whether there are differences in information available between different types of residency programs. Methods: This was a cross-sectional observational study of all US obstetrics and gynecology residency program website content. The authorship group identified factors that would be useful for residency applicants around program demographics and learner trajectories; application criteria including standardized testing metrics, residency statistics, and benefits; and diversity, equity, and inclusion mission statements and values. Two authors examined all available websites from November 2011 through March 2022. Data analysis consisted of descriptive statistics and one-way ANOVA, with P<.05 considered significant. Results: Among 290 programs, 283 (97.6%) had websites; 238 (82.1%) listed medical schools of current residents; 158 (54.5%) described residency alumni trajectories; 107 (36.9%) included guidance related to the preferred United States Medical Licensing Examination Step 1 scores; 53 (18.3%) included guidance related to the Comprehensive Osteopathic Medical Licensing Examination Level 1 scores; 185 (63.8%) included international applicant guidance; 132 (45.5%) included a program-specific mission statement; 84 (29%) included a diversity, equity, and inclusion statement; and 167 (57.6%) included program-specific media or links to program social media on their websites. University-based programs were more likely to include a variety of information compared to community-based university-affiliated and community-based programs, including medical schools of current residents (113/123, 91.9%, university-based; 85/111, 76.6%, community-based university-affiliated; 40/56, 71.4%, community-based; P<.001); alumni trajectories (90/123, 73.2%, university-based; 51/111, 45.9%, community-based university-affiliated; 17/56, 30.4%, community-based; P<.001); the United States Medical Licensing Examination Step 1 score guidance (58/123, 47.2%, university-based; 36/111, 32.4%, community-based university-affiliated; 13/56, 23.2%, community-based; P=.004); and diversity, equity, and inclusion statements (57/123, 46.3%, university-based; 19/111, 17.1%, community-based university-affiliated; 8/56, 14.3%, community-based; P<.001). Conclusions: There are opportunities to improve the quantity and quality of data on residency websites. From this work, we propose best practices for what information should be included on residency websites that will enable applicants to make informed decisions.

Spinal Cord Stimulation Improves Quality of Life for Patients With Chronic Pain-Data From the UK and Ireland National Neuromodulation Registry.

INTRODUCTION: Spinal cord stimulation (SCS) is a well-established treatment for chronic pain and is supported by numerous studies. However, some recent articles have questioned its efficacy. This article examines a cohort of >1800 patients with SCS from the UK and Ireland National Neuromodulation Registry. It is intended to provide a "real-world" assessment of efficacy and compare its effects with other procedures performed for painful indications. MATERIALS AND METHODS: Quality of life (QoL) data (EuroQoL five-level [EQ5D]) and demographic data were extracted from the National Neuromodulation Registry for all patients (N = 1811) who underwent SCS for chronic pain in 27 centers in the UK between February 2018 and July 2022. These were compared with data from the published literature for other commonly performed elective surgical procedures. RESULTS: The EQ5D utility index increased by a mean of 0.202 in the 1236 patients with paired pre- and postoperative utility scores. The median utility was 0.263 (interquartile range [IQR] = 0.384; n = 1811) preoperatively, whereas at six months after the operation, it was 0.550 (IQR = 0.396; n = 1025), p < 0.0001, Wilcoxon rank sum test. The median utility score at 12 months postoperation was 0.548 (IQR = 0.417; n = 970). There was no difference in utility scores at six months and 12 months after implantation (p = 0.15, Wilcoxon rank sum test). There was a significant improvement in QoL in all five domains of the five-level EQ5D tool at six months after baseline (p < 0.01, for all subcategories), and this was sustained at one year after implantation. The baseline utility was lower than in patients who underwent elective surgery for other painful conditions, and the absolute (and proportionate) increase in utility produced by SCS was greater than that achieved with most other interventions. CONCLUSIONS: SCS increases the QoL in patients requiring surgery for pain. Similar results were seen regardless of SCS indication. When comparing analogous data bases, SCS produces a greater percentage improvement in EQ5D utility than do many other elective surgical procedures for painful conditions, including spinal surgery and some joint replacements.

The Neurostimulation Appropriateness Consensus Committee (NACC)®: Recommendations for Spinal Cord Stimulation Long-Term Outcome Optimization and Salvage Therapy.

INTRODUCTION: The International Neuromodulation Society (INS) has recognized a need to establish best practices for optimizing implantable devices and salvage when ideal outcomes are not realized. This group has established the Neurostimulation Appropriateness Consensus Committee (NACC)® to offer guidance on matters needed for both our members and the broader community of those affected by neuromodulation devices. MATERIALS AND METHODS: The executive committee of the INS nominated faculty for this NACC® publication on the basis of expertise, publications, and career work on the issue. In addition, the faculty was chosen in consideration of diversity and inclusion of different career paths and demographic categories. Once chosen, the faculty was asked to grade current evidence and along with expert opinion create consensus recommendations to address the lapses in information on this topic. RESULTS: The NACC® group established informative and authoritative recommendations on the salvage and optimization of care for those with indwelling devices. The recommendations are based on evidence and expert opinion and will be expected to evolve as new data are generated for each topic. CONCLUSIONS: NACC® guidance should be considered for any patient with less-than-optimal outcomes with a stimulation device implanted for treating chronic pain. Consideration should be given to these consensus points to salvage a potentially failed device before explant.

Auditory cues modulate the short timescale dynamics of STN activity during stepping in Parkinson's disease.

BACKGROUND: Gait impairment has a major impact on quality of life in patients with Parkinson's disease (PD). It is believed that basal ganglia oscillatory activity at ß frequencies (15-30 Hz) may contribute to gait impairment, but the precise dynamics of this oscillatory activity during gait remain unclear. Additionally, auditory cues are known to lead to improvements in gait kinematics in PD. If the neurophysiological mechanisms of this cueing effect were better understood they could be leveraged to treat gait impairments using adaptive Deep Brain Stimulation (aDBS) technologies. OBJECTIVE: We aimed to characterize the dynamics of subthalamic nucleus (STN) oscillatory activity during stepping movements in PD and to establish the neurophysiological mechanisms by which auditory cues modulate gait. METHODS: We studied STN local field potentials (LFPs) in eight PD patients while they performed stepping movements. Hidden Markov Models (HMMs) were used to discover transient states of spectral activity that occurred during stepping with and without auditory cues. RESULTS: The occurrence of low and high ß bursts was suppressed during and after auditory cues. This manifested as a decrease in their fractional occupancy and state lifetimes. Interestingly, α transients showed the opposite effect, with fractional occupancy and state lifetimes increasing during and after auditory cues. CONCLUSIONS: We show that STN oscillatory activity in the α and ß frequency bands are differentially modulated by gait-promoting oscillatory cues. These findings suggest that the enhancement of α rhythms may be an approach for ameliorating gait impairments in PD.

Optimization in Visual Motion Estimation.

Sighted animals use visual signals to discern directional motion in their environment. Motion is not directly detected by visual neurons, and it must instead be computed from light signals that vary over space and time. This makes visual motion estimation a near universal neural computation, and decades of research have revealed much about the algorithms and mechanisms that generate directional signals. The idea that sensory systems are optimized for performance in natural environments has deeply impacted this research. In this article, we review the many ways that optimization has been used to quantitatively model visual motion estimation and reveal its underlying principles. We emphasize that no single optimization theory has dominated the literature. Instead, researchers have adeptly incorporated different computational demands and biological constraints that are pertinent to the specific brain system and animal model under study. The successes and failures of the resulting optimization models have thereby provided insights into how computational demands and biological constraints together shape neural computation.

Evaluation of 3D C-Arm Fluoroscopy versus Diagnostic CT for Deep Brain Stimulation Stereotactic Registration and Post-Operative Lead Localization.

INTRODUCTION: DBS efficacy depends on accuracy. CT-MRI fusion is established for both stereotactic registration and electrode placement verification. The desire to streamline DBS workflows, reduce operative time, and minimize patient transfers has increased interest in portable imaging modalities such as the Medtronic O-arm® and mobile CT. However, these remain expensive and bulky. 3D C-arm fluoroscopy (3DXT) units are a smaller and less costly alternative, albeit incompatible with traditional frame-based localization and without useful soft tissue resolution. We aimed to compare fusion of 3DXT and CT with pre-operative MRI to evaluate if 3DXT-MRI fusion alone is sufficient for accurate registration and reliable targeting verification. We further assess DBS targeting accuracy using a 3DXT workflow and compare radiation dosimetry between modalities. METHODS: Patients underwent robot-assisted DBS implantation using a workflow incorporating 3DXT which we describe. Two intra-operative 3DXT spins were performed for registration and accuracy verification followed by conventional CT post-operatively. Post-operative 3DXT and CT images were independently fused to the same pre-operative MRI sequence and co-ordinates generated for comparison. Registration accuracy was compared to 15 consecutive controls who underwent CT-based registration. Radial targeting accuracy was calculated and radiation dosimetry recorded. RESULTS: Data were obtained from 29 leads in 15 consecutive patients. 3DXT registration accuracy was significantly superior to CT with mean error 0.22 ± 0.03 mm (p < 0.0001). Mean Euclidean electrode tip position variation for CT to MRI versus 3DXT to MRI fusion was 0.62 ± 0.40 mm (range 0.0 mm-1.7 mm). In comparison, direct CT to 3DXT fusion showed electrode tip Euclidean variance of 0.23 ± 0.09 mm. Mean radial targeting accuracy assessed on 3DXT was 0.97 ± 0.54 mm versus 1.15 ± 0.55 mm on CT with differences insignificant (p = 0.30). Mean patient radiation doses were around 80% lower with 3DXT versus CT (p < 0.0001). DISCUSSION: Mobile 3D C-arm fluoroscopy can be safely incorporated into DBS workflows for both registration and lead verification. For registration, the limited field of view requires the use of frameless transient fiducials and is highly accurate. For lead position verification based on MRI co-registration, we estimate there is around a 0.4 mm discrepancy between lead position seen on 3DXT versus CT when corrected for brain shift. This is similar to that described in O-arm® or mobile CT series. For units where logistical or financial considerations preclude the acquisition of a cone beam CT or mobile CT scanner, our data support portable 3D C-arm fluoroscopy as an acceptable alternative with significantly lower radiation exposure.

How medical students' trauma histories affect their clinical clerkship experiences.

BACKGROUND: As the gender demographics of medical students have evolved over the past decades, it is important to understand potential stressors and challenges that may affect clinical learning experiences. This study investigated the prevalence of prior sexual assault (SA) and interpersonal violence (IPV) in medical students and how these affect their clinical clerkship experiences. METHODS: A survey was distributed to third- and fourth-year medical students at a single institution in August 2022 querying respondents on demographics and prior experiences with SA/IPV at any point in their lives. Respondents who indicated they had previously experienced SA/IPV were directed to questions about how these experiences affected clerkships. FINDINGS: Of 419 students, 125 responded to the survey (30.8% response rate). Forty (31.1%) reported a history of SA/IPV-32 (80.0%) women, five (12.5%) men, and three (7.5%) who did not report gender or identified as non-binary. Of the 40 respondents with a history of SA/IPV, 20 (50.0%) reported that their prior history affected their overall clinical experience, and nine (22.5%) felt that it affected their performance. Only seven (17.5%) reported using any resources, such as counselling, during their clerkships. Narrative responses discussed significant effects on performing physical exams, taking a history, interacting with team members, and engaging during clerkships. DISCUSSION: This work demonstrates the high number of students affected by SA/IPV and how these prior experiences affected core components of their clerkship experiences. CONCLUSIONS: Institutions must be proactive to create better supports for learners with histories of trauma, including SA/IPV.

A mixed-methods SWOT analysis of a medical student Balint group programme.

BACKGROUND: Balint groups use case-based discussions to explore, reflect on, and enhance the clinician-patient relationship. They facilitate the development of empathy and reflective practice and reduce burnout. This study aimed to explore how the benefits of a traditional Balint group format can be accessed and optimised for medical students during a one-year pilot programme. METHODS: Eight medical student Balint groups ran for six weeks during 2022-2023, with 90 students participating. Themes were identified from student feedback using qualitative content analysis. Group leaders kept reflective session notes and used these alongside student feedback to undertake a strengths, weaknesses, opportunities, and threats analysis. RESULTS: Strengths of the programme were emotional containment, learning to reflect, and community identity. Weaknesses were themed as strange situations, dragging along, and facilitator as an object. Opportunities were identified in expanding the scope and sharpening focus. Psychological defences and the engagement dilemma threatened the future success of the Balint group programme. DISCUSSION: Medical student Balint groups provide a unique space to combine learning and emotional support with personal, professional and community development. However, the traditional Balint group format may need adapting to be widely accessible to undergraduate learners. Sustainably integrating Balint groups into the medical school curriculum requires ongoing engagement work at both an individual and organisational level.

Seeing Is Believing: Photon Counting Computed Tomography Clearly Images Directional Deep Brain Stimulation Lead Segments and Markers After Implantation.

BACKGROUND AND OBJECTIVES: Directional deep brain stimulation (DBS) electrodes are increasingly used, but conventional computed tomography (CT) is unable to directly image segmented contacts owing to physics-based resolution constraints. Postoperative electrode segment orientation assessment is necessary because of the possibility of significant deviation during or immediately after insertion. Photon-counting detector (PCD) CT is a relatively novel technology that enables high resolution imaging while addressing several limitations intrinsic to CT. We show how PCD CT can enable clear in vivo imaging of DBS electrodes, including segmented contacts and markers for all major lead manufacturers. MATERIALS AND METHODS: We describe postoperative imaging and reconstruction protocols we have developed to enable optimal lead visualization. PCD CT images were obtained of directional leads from the three major manufacturers and fused with preoperative 3T magnetic resonance imaging (MRI). Radiation dosimetry also was evaluated and compared with conventional imaging controls. Orientation estimates from directly imaged leads were compared with validated software-based reconstructions (derived from standard CT imaging artifact analysis) to quantify congruence in alignment and directional orientation. RESULTS: High-fidelity images were obtained for 15 patients, clearly indicating the segmented contacts and directional markers both on CT alone and when fused to MRI. Our routine imaging protocol is described. Ionizing radiation doses were significantly lower than with conventional CT. For most leads, the directly imaged lead orientations and depths corresponded closely to those predicted by CT artifact-based reconstructions. However, unlike direct imaging, the software reconstructions were susceptible to 180° error in orientation assessment. CONCLUSIONS: High-resolution photon-counting CT can very clearly image segmented DBS electrode contacts and directional markers and unambiguously determine lead orientation, with lower radiation than in conventional imaging. This obviates the need for further imaging and may facilitate anatomically tailored directional programming.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

From national and regional commitments to global impact: artificial intelligence for equitable public health at the G20

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