Repeated L5 Nerve Root Compromise Detected with Motor Evoked Potentials (MEP), but Not Electromyography (EMG): A Case Report.

We report a case where neuromonitoring, using motor evoked potentials (MEP), detected an intraoperative L5 nerve root deficit during a lumbosacral decompression and instrumented fusion procedure. Critically, the MEP changes were not preceded nor accompanied by any significant spontaneous electromyography (sEMG) activity. Presumptive L5 innervated muscles, including tibialis anterior (TA), extensor hallucis longus (EHL) and gluteus maximus, were targets for nerve root surveillance using combined MEP and sEMG techniques. During a high-grade spondylolisthesis correction procedure, attempts to align a left-sided rod resulted in repeated loss and recovery cycles of MEP from the TA and EHL. No accompanying EMG alerts were associated with any of the MEP changes nor were MEP variations seen from muscles innervated above and below L5. After several attempts, the rod alignment was achieved, but significant MEP signal decrement (72% decrease) remained from the EHL. Postoperatively, the patient experienced significant foot drop on the left side that recovered over a period of 3 months. This case contributes to a growing body of evidence that exclusive reliance on sEMG for spinal nerve root scrutiny can be unreliable and MEP may provide more dependable data on nerve root patency.

Cathodal Genesis of Ipsilateral Hand (Crossover) Motor Evoked Potentials: Evidence from a Patient with Previous Stroke.

A case is described where baseline transcranial electrical motor evoked potentials (TcMEP) and somatosensory evoked potentials (SSEP) results were unilaterally absent in a patient with previous hemispheric stroke undergoing a right-sided carotid endarterectomy. SSEP data confirmed right cortical pathology and excluded a technical rationale for absent motor evoked responses. Attempts at generating left-hand (contralateral) TcMEP from right cortical anodal stimulation failed despite high stimulus intensities. However, TcMEP responses from anodal stimulation of the right cortex were recorded from the right-hand (ipsilateral) which were attributed to "crossover." Ipsilateral TcMEP onset latencies derived from the stimulus-response data supports the idea that crossover is a product of cathodal stimulation initially acting on pericortical motor pathways.

Current recommendations/practices for anonymising data from clinical trials in order to make it available for sharing: A scoping review.

BACKGROUND/AIMS: There are increasing pressures for anonymised datasets from clinical trials to be shared across the scientific community, and differing recommendations exist on how to perform anonymisation prior to sharing. We aimed to systematically identify, describe and synthesise existing recommendations for anonymising clinical trial datasets to prepare for data sharing. METHODS: We systematically searched MEDLINE®, EMBASE and Web of Science from inception to 8 February 2021. We also searched other resources to ensure the comprehensiveness of our search. Any publication reporting recommendations on anonymisation to enable data sharing from clinical trials was included. Two reviewers independently screened titles, abstracts and full text for eligibility. One reviewer extracted data from included papers using thematic synthesis, which then was sense-checked by a second reviewer. Results were summarised by narrative analysis. RESULTS: Fifty-nine articles (from 43 studies) were eligible for inclusion. Three distinct themes are emerging: anonymisation, de-identification and pseudonymisation. The most commonly used anonymisation techniques are: removal of direct patient identifiers; and careful evaluation and modification of indirect identifiers to minimise the risk of identification. Anonymised datasets joined with controlled access was the preferred method for data sharing. CONCLUSIONS: There is no single standardised set of recommendations on how to anonymise clinical trial datasets for sharing. However, this systematic review shows a developing consensus on techniques used to achieve anonymisation. Researchers in clinical trials still consider that anonymisation techniques by themselves are insufficient to protect patient privacy, and they need to be paired with controlled access.

Effect of Strongly Magnetized Electrons and Ions on Heat Flow and Symmetry of Inertial Fusion Implosions.

This Letter presents the first observation on how a strong, 500 kG, externally applied B field increases the mode-two asymmetry in shock-heated inertial fusion implosions. Using a direct-drive implosion with polar illumination and imposed field, we observed that magnetization produces a significant increase in the implosion oblateness (a 2.5× larger P2 amplitude in x-ray self-emission images) compared with reference experiments with identical drive but with no field applied. The implosions produce strongly magnetized electrons (ω_{e}τ_{e}≫1) and ions (ω_{i}τ_{i}>1) that, as shown using simulations, restrict the cross field heat flow necessary for lateral distribution of the laser and shock heating from the implosion pole to the waist, causing the enhanced mode-two shape.

A novel method for quantitative evaluation of motor evoked potential monitoring during cerebrovascular surgeries.

Transcranial motor evoked potential (MEP) monitoring, intended to assess cerebral cortical ischemia, may produce false negative results when the stimulation inadvertently activates the deep, subcortical motor pathways. This study examined hand MEP onset latency as a potential means to differentiate superficial versus deep stimulus penetration in surgical patients monitored for cerebral ischemia. Intraoperative MEP data were prospectively collected from 40 patients treated for intracranial aneurysm or carotid stenosis. Onset latencies of hand MEP responses were measured over a range of stimulation intensities from both the contralateral and ipsilateral hand (crossover responses). At the threshold for superficial, cortical stimulation of the contralateral hand, the MEP latency was 26.9 ± 0.4 ms. MEP onset latencies measurements became shorter as stimulation intensities were increased. At the maximum intensity (when crossover response was usually generated), the contralateral hand MEP latency of 22.5 ± 0.3 ms was significantly shorter than at threshold stimulation (p < 0.001). Latency-stimulus intensity plots best fit a 3 parameter hyperbolic decay function (r2 = 0.85 ± 0.02) and revealed a narrow window of acceptable MEP stimuli to obtain superficial cortical activation. Our analysis refutes the utility of the crossover response in reliably gauging depth of activation. Additionally, we found that differentiation between long and short MEP onset latency times may serve as a dependable marker for depth of stimulation. Attention to hand MEP onset latency may reduce inadvertent stimulation of the deep corticospinal tract pathways and avoid false negative MEP recordings during cerebrovascular surgeries.

High-resolution x-ray radiography with Fresnel zone plates on the University of Rochester's OMEGA Laser Systems.

Experiments performed at the Laboratory for Laser Energetics with a continuous-wave (cw) x-ray source and on the OMEGA and OMEGA EP Laser Systems [Boehly et al., Opt. Commun. 133, 495 (1997) and Waxer et al., Opt. Photonics News 16, 30 (2005)] have utilized a Fresnel zone plate (FZP) to obtain x-ray images with a spatial resolution as small as ∼1.5 µm. Such FZP images were obtained with a charge-coupled device or a framing camera at energies ranging from 4.5 keV to 6.7 keV using x-ray line emission from both the cw source and high-intensity, laser-beam-illuminated metal foils. In all cases, the resolution test results are determined from patterns and grids backlit by these sources. The resolutions obtained are shown to be due to a combination of the spectral content of the x-ray sources and detector resolution limited by the magnification of the images (14× to 22×). High-speed framing cameras were used to obtain FZP images with frame times as short as ∼30 ps. Double-shell implosions on OMEGA were backlit by laser-irradiated Fe foils, thus obtaining a framing-camera-limited, FZP-image resolution of ∼3 µm-4 µm.

Peripheral leg ischemia detected via intraoperative neurophysiological monitoring during a multilevel complex anterior and posterior operation.

Intraoperative neurophysiologic monitoring is a technique utilized during spinal operations to minimize sensory and motor function morbidity. We herein report a case of a 73-year-old female with renal cell carcinoma and metastatic involvement of the cervical and thoracic spine, who underwent a multilevel complex anterior and posterior operation. Neurophysiological monitoring was able to localize the lower limb ischemia utilizing somatosensory evoked potentials. This prompted intraoperative investigation of the peripheral ischemia, and the patient was found to have an Angio-Seal device embolus in the right popliteal artery that dislodged from the right femoral artery.

Inferred UV fluence focal-spot profiles from soft x-ray pinhole-camera measurements on OMEGA.

A method was developed with laser-irradiated Au planar foils to characterize the focal spot of UV laser beams on a target at full energy from soft x-ray emission. A pinhole camera with a back-thinned charge-coupled device detector and filtration with thin Be and Al foil filters provides images of the x-ray emission at photon energies <2 keV. This method requires a careful measurement of the relationship between the applied UV fluence and the x-ray signal, which can be described by a power-law dependence. The measured exponent γ ∼ 2 provides a dynamic range of ∼25 for the inferred UV fluence. UV fluence profiles of selected beams were measured for 100-ps and 1-ns laser pulses and were compared to directly measured profiles from an UV equivalent-target-plane diagnostic. The inferred spot size and super-Gaussian order from the x-ray technique agree within several percent with the values measured with the direct UV measurements.

Using strength-duration analysis to identify the afferent limb of the lateral spread response in hemifacial spasm patients during microvascular decompression surgery.

Strength-duration analysis has been used to identify excitability differences between motor and sensory axons in human peripheral mixed nerves. The trigeminal and facial nerves have both been suggested to play a role in mediating the lateral spread response (LSR) in patients with hemifacial spasm (HFS). We sought to investigate this hypothesis by analyzing strength-duration properties of spasm side mentalis M wave and o. oculi LSR in 22 patients undergoing microvascular decompression surgery for HFS. Simultaneous recordings of mentalis M wave and o. oculi LSR prior to dural opening were collected following marginal mandibular facial nerve branch stimulation. Threshold responses were observed at stimulus pulse widths from 0.05 to 1.0 ms and the chronaxie and rheobase calculated from charge versus stimulus pulse width plots. The mean chronaxie (±SEM) of mentalis M wave was 0.34 ± 0.03 ms and 0.33 ± 0.04 ms for the LSR (p = 0.42, one-tailed t-test). The rheobase for the M wave (8.0 ± 1.0 mA) was found to be significantly different than the LSR rheobase (5.7 ± 0.7 mA; p = 0.03, one-tailed t-test) likely due to differences in the threshold amplitudes of the M wave versus the LSR. These results are highly suggestive of the facial nerve and not the trigeminal nerve in mediating the LSR.

Tripled yield in direct-drive laser fusion through statistical modelling.

Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium-tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules-several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.

The single-line-of-sight, time-resolved x-ray imager diagnostic on OMEGA.

The single-line-of-sight, time-resolved x-ray imager (SLOS-TRXI) on OMEGA is one of a new generation of fast-gated x-ray cameras comprising an electron pulse-dilation imager and a nanosecond-gated, burst-mode, hybrid complementary metal-oxide semiconductor sensor. SLOS-TRXI images the core of imploded cryogenic deuterium-tritium shells in inertial confinement fusion experiments in the ∼4- to 9-keV photon energy range with a pinhole imager onto a photocathode. The diagnostic is mounted on a fixed port almost perpendicular to a 16-channel, framing-camera-based, time-resolved Kirkpatrick-Baez microscope, providing a second time-gated line of sight for hot-spot imaging on OMEGA. SLOS-TRXI achieves ∼40-ps temporal resolution and better than 10-µm spatial resolution. Shots with neutron yields of up to 1 × 1014 were taken without observed neutron-induced background signal. The implosion images from SLOS-TRXI show the evolution of the stagnating core.

Lifestyle and neurodegeneration in midlife as expressed on functional magnetic resonance imaging: A systematic review.

INTRODUCTION: Lifestyle factors may influence brain health in midlife. Functional magnetic resonance imaging is a widely used tool to investigate early changes in brain health, including neurodegeneration. In this systematic review, we evaluate the relationship between lifestyle factors and neurodegeneration in midlife, as expressed using functional magnetic resonance imaging. METHODS: We searched MEDLINE, EMBASE, and PsycINFO combining subject headings and free text terms adapted for each database. Articles were screened, and their quality was assessed independently by two reviewers before final inclusion in the review. RESULTS: We screened 4116 studies and included 29 in the review. Seven lifestyle factors, such as alcohol, cognitive training, excessive internet use, fasting, physical training, smoking, and substance misuse, were identified in this review. DISCUSSION: Cognitive and physical trainings appear to be associated with a neuroprotective effect, whereas alcohol misuse, smoking, and substance misuse appear to be associated with neurodegeneration. Further research is required into the effects of excessive internet use and fasting.

Protocol for Single-Stage Bilateral Temporomandibular Joint Replacement Using Intraoperative Navigation in Patients With Ankylosis.

Treatment of patients with bilateral temporomandibular joint (TMJ) ankylosis in a single-stage procedure can be challenging. The implementation of intraoperative navigation has proved beneficial by enabling faster and safer excision by providing real-time identification of vital structures. Navigation also can be used to verify site preparation for custom joint prostheses. This article seeks to establish a protocol, based on the use of intermaxillary fixation screws, to produce accurate and repeatable outcomes for the correction of bilateral TMJ ankylosis with total joint replacement in a single-stage procedure.

First Observation of Cross-Beam Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion Implosions Using Wavelength Detuning at the National Ignition Facility.

Cross-beam energy transfer (CBET) results from two-beam energy exchange via seeded stimulated Brillouin scattering, which detrimentally reduces ablation pressure and implosion velocity in direct-drive inertial confinement fusion. Mitigating CBET is demonstrated for the first time in inertial-confinement implosions at the National Ignition Facility by detuning the laser-source wavelengths (±2.3 Å UV) of the interacting beams. We show that, in polar direct-drive, wavelength detuning increases the equatorial region velocity experimentally by 16% and alters the in-flight shell morphology. These experimental observations are consistent with design predictions of radiation-hydrodynamic simulations that indicate a 10% increase in the average ablation pressure.

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova.

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow).

A framed, 16-image Kirkpatrick-Baez x-ray microscope.

A 16-image Kirkpatrick-Baez (KB)-type x-ray microscope consisting of compact KB mirrors [F. J. Marshall, Rev. Sci. Instrum. 83, 10E518 (2012)] has been assembled for the first time with mirrors aligned to allow it to be coupled to a high-speed framing camera. The high-speed framing camera has four independently gated strips whose emission sampling interval is ∼30 ps. Images are arranged four to a strip with ∼60-ps temporal spacing between frames on a strip. By spacing the timing of the strips, a frame spacing of ∼15 ps is achieved. A framed resolution of ∼6-µm is achieved with this combination in a 400-µm region of laser-plasma x-ray emission in the 2- to 8-keV energy range. A principal use of the microscope is to measure the evolution of the implosion stagnation region of cryogenic DT target implosions on the University of Rochester's OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The unprecedented time and spatial resolutions achieved with this framed, multi-image KB microscope have made it possible to accurately determine the cryogenic implosion core emission size and shape at the peak of stagnation. These core size measurements, taken in combination with those of ion temperature, neutron-production temporal width, and neutron yield allow for inference of core pressures, currently exceeding 50 Gbar in OMEGA cryogenic target implosions [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)].

Learning-Based Shadow Recognition and Removal From Monochromatic Natural Images.

This paper addresses the problem of recognizing and removing shadows from monochromatic natural images from a learning-based perspective. Without chromatic information, shadow recognition and removal are extremely challenging in this paper, mainly due to the missing of invariant color cues. Natural scenes make this problem even harder due to the complex illumination condition and ambiguity from many near-black objects. In this paper, a learning-based shadow recognition and removal scheme is proposed to tackle the challenges above-mentioned. First, we propose to use both shadow-variant and invariant cues from illumination, texture, and odd order derivative characteristics to recognize shadows. Such features are used to train a classifier via boosting a decision tree and integrated into a conditional random field, which can enforce local consistency over pixel labels. Second, a Gaussian model is introduced to remove the recognized shadows from monochromatic natural scenes. The proposed scheme is evaluated using both qualitative and quantitative results based on a novel database of hand-labeled shadows, with comparisons to the existing state-of-the-art schemes. We show that the shadowed areas of a monochromatic image can be accurately identified using the proposed scheme, and high-quality shadow-free images can be precisely recovered after shadow removal.

Significant and variable linear polarization during the prompt optical flash of GRB 160625B.

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent-consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions.

We present narrow-band self-emission x-ray images from a titanium tracer layer placed at the fuel-shell interface in 60-laser-beam implosion experiments at the OMEGA facility. The images are acquired during deceleration with inferred convergences of ∼9-14. Novel here is that a systematically observed asymmetry of the emission is linked, using full sphere 3D implosion modeling, to performance-limiting low mode asymmetry of the drive.

Analysis of facial motor evoked potentials for assessing a central mechanism in hemifacial spasm.

OBJECTIVE Hemifacial spasm (HFS) is a cranial nerve hyperactivity disorder characterized by unique neurophysiological features, although the underlying pathophysiology remains disputed. In this study, the authors compared the effects of desflurane on facial motor evoked potentials (MEPs) from the spasm and nonspasm sides of patients who were undergoing microvascular decompression (MVD) surgery to test the hypothesis that HFS is associated with a central elevation of facial motor neuron excitability. METHODS Facial MEPs were elicited in 31 patients who were undergoing MVD for HFS and were administered total intravenous anesthesia (TIVA) with or without additional desflurane, an inhaled anesthetic known to centrally suppress MEPs. All measurements were completed before dural opening while a consistent mean arterial blood pressure was maintained and electroencephalography was performed. The activation threshold voltage and mean amplitudes of the MEPs from both sides of the face were compared. RESULTS There was a significantly lower mean activation threshold of facial MEPs on the spasm side than on the nonspasm side (mean ± SD 162.9 ± 10.1 vs 198.3 ± 10.1 V, respectively; p = 0.01). In addition, MEPs were also elicited more readily when single-pulse transcranial electrical stimulation was used on the spasm side (74% vs 31%, respectively; p = 0.03). Although desflurane (1 minimum alveolar concentration) suppressed facial MEPs on both sides, the suppressive effects of desflurane were less on the spasm side than on the nonspasm side (59% vs 79%, respectively; p = 0.03), and M waves recorded from the mentalis muscle remained unchanged, which indicates that desflurane did not affect the peripheral facial nerve or neuromuscular junction. CONCLUSIONS Centrally acting inhaled anesthetic agents can suppress facial MEPs and therefore might interfere with intraoperative monitoring. The elevated motor neuron excitability and differential effects of desflurane between the spasm and nonspasm sides support a mechanism of central pathophysiology in HFS. Clinical trial registration no.: B2012:099 ( clinicaltrials.gov ).