Antiganglioside antibody frequency in routine clinical care settings.

BACKGROUND AND PURPOSE: Antiganglioside antibodies (AGAs) might be involved in the etiopathogenesis of many neurological diseases, such as Miller-Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS). Available comprehensive reference data regarding AGA positivity rates and cross-responsiveness among AGAs (where one line immunoblot is positive for ≥1 AGA) during routine clinical care are scant. METHODS: In this 10-year monocentric retrospective study, 3560 immunoglobulin (Ig) G and IgM line blots (GA Generic Assays' Anti-Ganglioside Dot kit) obtained using cerebrospinal fluid (CSF) and serum samples from 1342 patients were analyzed for AGA positivity in terms of 14 diagnosis categories and AGA cross-responsiveness. RESULTS: Of all 3560 line blots 158 (4.4%) and of all CSF samples 0.4% (4/924) CSF line blots were AGA positive. For serum IgG, blots with positivity rates higher than the standard deviation of 15.6% were associated with MFS (GD3, GD1a, GT1a and GQ1b) and acute motor axonal neuropathy (AMAN) (GM1, GD1a and GT1a). For serum IgM, blots with positivity rates higher than the standard deviation of 8.1% were associated with AMAN (GM2, GT1a and GQ1b), MFS (GM1, GT1a and GQ1b), multifocal motor neuropathy (MMN) (GM1, GM2 and GQ1b) and chronic inflammatory demyelinating polyneuropathy (CIDP) (GM1). Cross-responsiveness was observed in 39.6% of all positive serum AGA. CONCLUSIONS: Testing for AGAs during routine clinical care rarely led to positive findings, both in serum and even less in CSF, except for the diagnoses AMAN, MFS, MMN and CIDP. Nonspecific findings found as cross-responsiveness between different AGA samples occur frequently, impacting the positivity of most AGA subtypes.

Is it possible to generate an additional pleasant and pain-relieving muscle stimulation when using a low-frequency spinal cord stimulation (SCS) for the treatment of lower back pain? Pilot study: A new technique: "MuscleSCS".

OBJECTIVE: The combined use of spinal cord stimulation (SCS) and muscle stimulation, in the treatment of chronic pain, using the same probe, could improve the clinical results. However, this technique has not been established as yet. It was our hypothesis that it is possible to generate muscle stimulation by using low frequencies with SCS electrodes and use it to additionally treat chronic back pain. METHODS: We generated muscle stimulation in patients with previously implanted SCS electrodes, for the treatment of lower back pain, by using low frequencies (2, 4, 6, and 8 Hz) and different contact combinations of the electrodes. The results were evaluated by using visual inspection (videos), haptic control, surface electromyography (EMG), and sonographic recordings. RESULTS: This pilot study (17 patients, seven females, age 36-87 years, 11 percutaneous paddle leads, and 6 octrodes) was performed at the Neurosurgical Department of the University of Tuebingen. The most preferred frequencies were 6 Hz (45.5% of percutaneous paddle leads) and 8 Hz (50% of octrodes) at contacts 3&4 or 5&6. The preference of frequencies differed significantly among genders (p = 0.023). Simultaneous EMG and ultrasonic recordings demonstrated the generation of muscle potentials and the stimulation of deeper muscle groups. CONCLUSION: In this study, it has been shown that with low-frequency SCS stimulation, pleasant and pain-relieving muscle contractions of the lower and upper back can also be generated. This combined method has been coined by us as "MuscleSCS" technique. Clinical trials are necessary to establish the value of this combined technique and its subtypes.

Combined electrophysiological and morphological phenotypes in patients with genetic generalized epilepsy and their healthy siblings.

OBJECTIVE: Genetic generalized epilepsy (GGE) is characterized by aberrant neuronal dynamics and subtle structural alterations. We evaluated whether a combination of magnetic and electrical neuronal signals and cortical thickness would provide complementary information about network pathology in GGE. We also investigated whether these imaging phenotypes were present in healthy siblings of the patients to test for genetic influence. METHODS: In this cross-sectional study, we analyzed 5 min of resting state data acquired using electroencephalography (EEG) and magnetoencephalography (MEG) in patients, their siblings, and controls, matched for age and sex. We computed source-reconstructed power and connectivity in six frequency bands (1-40 Hz) and cortical thickness (derived from magnetic resonance imaging). Group differences were assessed using permutation analysis of linear models for each modality separately and jointly for all modalities using a nonparametric combination. RESULTS: Patients with GGE (n = 23) had higher power than controls (n = 35) in all frequencies, with a more posterior focus in MEG than EEG. Connectivity was also increased, particularly in frontotemporal and central regions in theta (strongest in EEG) and low beta frequencies (strongest in MEG), which was eminent in the joint EEG/MEG analysis. EEG showed weaker connectivity differences in higher frequencies, possibly related to drug effects. The inclusion of cortical thickness reinforced group differences in connectivity and power. Siblings (n = 18) had functional and structural patterns intermediate between those of patients and controls. SIGNIFICANCE: EEG detected increased connectivity and power in GGE similar to MEG, but with different spectral sensitivity, highlighting the importance of theta and beta oscillations. Cortical thickness reductions in GGE corresponded to functional imaging patterns. Our multimodal approach extends the understanding of the resting state in GGE and points to genetic underpinnings of the imaging markers studied, providing new insights into the causes and consequences of epilepsy.

Delirium: Prevalence and outcome in the very old in 27 medical departments during a one-year prospective study.

OBJECTIVE: The prevalence and effects of delirium in very old individuals aged ≥80 years have not yet been systematically evaluated. Therefore, this large single-center study of the one-year prevalence of delirium in 3,076 patients in 27 medical departments of the University Hospital of Zurich was conducted. METHODS: Patient scores on the Delirium Observation Screening scale, Intensive Care Delirium Screening Checklist, Diagnostic and Statistical Manual, 5th edition, and electronic Patient Assessment-Acute Care (nursing tool) resulted in the inclusion of 3,076 individuals in 27 departments. The prevalence rates were determined by simple logistic regressions, odds ratios (ORs), and confidence intervals. RESULTS: Of the 3,076 patients, 1,285 (41.8%) developed delirium. The prevalence rates in the 27 departments ranged from 15% in rheumatology (OR = 0.30) to 73% in intensive care (OR = 5.25). Delirious patients were more likely to have been admitted from long-term care facilities (OR = 2.26) or because of emergencies (OR = 2.24). The length of their hospital stay was twice as long as that for other patients. Some died before discharge (OR = 24.88), and others were discharged to nursing homes (OR = 2.96) or assisted living facilities (OR = 2.2). CONCLUSION: This is the largest study to date regarding the prevalence of delirium in patients aged ≥80 years and the medical characteristics of these patients. Almost two out of five patients developed delirium, with a high risk of loss of independence and mortality.

Predisposing and Precipitating Factors for Delirium in the Very Old (≥80 Years): A Prospective Cohort Study of 3,076 Patients.

BACKGROUND: Predisposing and precipitating factors for delirium for the elderly, over the age of 65 years, are known, but not for the very old, over 80 years. As the society is getting older and evermore patients will reach >80 years, more evidence of the factors and their contribution to delirium is required in this patient group. METHODS: In the course of 1 year, 3,076 patients above 80 years were screened prospectively for delirium based on a Delirium Observation Screening (DOS) scale, Intensive Care Delirium Screening Checklist (ICDSC), and a DSM (Diagnostic and Statistical Manual)-5 nursing instrument (ePA-AC) construct. Relevant predisposing and precipitating factors for delirium were assessed with a multiple regression analysis. RESULTS: Of 3,076 patients above 80 years, 1,285 (41.8%) developed a delirium, which led to twice prolonged hospitalization (p < 0.001), requirement for subsequent assisted living (OR 2.2, CI: 1.73-2.8, p < 0.001), and increased mortality (OR 24.88, CI: 13.75-45.03, p < 0.001). Relevant predisposing factors were dementia (OR 15.6, CI: 10.17-23.91, p < 0.001), pressure sores (OR 4.61, CI: 2.74-7.76, p < 0.001), and epilepsy (OR 3.65, CI: 2.12-6.28, p < 0.0001). Relevant precipitating factors were acute renal failure (4.96, CI: 2.38-10.3, p < 0.001), intracranial hemorrhage (OR 8.7, CI: 4.27-17.7, p < 0.001), and pleural effusions (OR 3.25, CI: 1.77-17.8, p < 0.001). CONCLUSION: Compared to the general delirium rate of approximately 20%, the prevalence of delirium doubled above the age of 80 years (41.8%) due to predisposing factors uncommon in younger patients.

Limitations of Muscle Ultrasound Shear Wave Elastography for Clinical Routine-Positioning and Muscle Selection.

Shear wave elastography (SWE) is a clinical ultrasound imaging modality that enables non-invasive estimation of tissue elasticity. However, various methodological factors-such as vendor-specific implementations of SWE, mechanical anisotropy of tissue, varying anatomical position of muscle and changes in elasticity due to passive muscle stretch-can confound muscle SWE measurements and increase their variability. A measurement protocol with a low variability of reference measurements in healthy subjects is desirable to facilitate diagnostic conclusions on an individual-patient level. Here, we present data from 52 healthy volunteers in the areas of: (1) Characterizing different limb and truncal muscles in terms of inter-subject variability of SWE measurements. Superficial muscles with little pennation, such as biceps brachii, exhibit the lowest variability whereas paravertebral muscles show the highest. (2) Comparing two protocols with different limb positioning in a trade-off between examination convenience and SWE measurement variability. Repositioning to achieve low passive extension of each muscle results in the lowest SWE variability. (3) Providing SWE shear wave velocity (SWV) reference values for a specific ultrasound machine/transducer setup (Canon Aplio i800, 18 MHz probe) for a number of muscles and two positioning protocols. We argue that methodological issues limit the current clinical applicability of muscle SWE.

Ammonia and coma - a case report of late onset hemizygous ornithine carbamyltransferase deficiency in 68-year-old female.

BACKGROUND: Acute hyperammonemia without signs of common causes in the elderly might be challenging to identify. We report the oldest case known to date of a female patient with late onset ornithine carbamyltransferase deficiency (OTC), which was unmasked after a protein overload due to nutritional supplements. Our case illustrates how environmental factors (protein overload) in previously unknown OTC in the elderly leads to hyperammonemic encephalopathy and highlights that early treatment prevents persisting neurological deficits and should be considered in absence of common causes of hyperammonemic encephalopathy. CASE PRESENTATION: A 68-year-old woman presented with acute confusion, which progressed into a deep coma (Glasgow-Coma-Scale score 3) within a few hours. The only remarkable finding was a plasma ammonia (NH3) concentration of 697 µmmol/l (range 12-47 µmmol/). Third party history revealed that the patient disliked meat for most of her life (meat = protein, which needs to be metabolized) and had taken nutritional supplements (since supplements often have a high protein-ratio) 2 days before the symptoms started. Protein catabolism results in NH3, which is metabolized via the urea cycle. Consequently, the acute hyperammonemia in our patient was thought to be related to an inherited metabolic disorder, which only unmasked itself as a result of an overload of the corresponding metabolite (in this case protein). Since ornithine carbamyltransferase deficiency (OTC) is the most common inherited urea cycle disorder, this diagnosis became likely and was confirmed later via genetic and metabolic testing (amino acids, orotic acid, etc.). After 2 weeks of treatment (dialysis, low-protein-diet, nitrogen-lowering medication) the patient was discharged in a healthy condition without any neurological deficits. CONCLUSION: OTC is a x-chromosomal linked disorder, that usually manifests in newborn infants and children, but also rarely in adults and even rarer in the elderly (50- till 60-years-old), where it is probably underdiagnosed. In case of hyperammonemic encephalopathy - regardless of the underlying cause -, treatment should be started early to prevent persisting neurological deficits. OTC should be considered in absence of common causes of hyperammonemic encephalopathy.

The utility of nursing instruments for daily screening for delirium: Delirium causes substantial functional impairment.

OBJECTIVE: Nursing assessments have been recommended for the daily screening for delirium; however, the utility of individual items have not yet been tested. In a first step in establishing the potential of the electronic Patient Assessment-Acute Care (ePA-AC) as such, the impact of delirium on the functional domains was assessed. METHOD: In this prospective observational cohort study, 277 patients were assessed and 118 patients were delirious. The impact of delirium on functional domains of the ePA-AC related to self-initiated activity, nutrition, and elimination was determined with simple logistic regressions. RESULTS: Patients with delirium were older, sicker, were more commonly sedated during the assessment, stayed longer in the intensive care unit (ICU) and floors, and less commonly discharged home. A general pattern was the loss of abilities and full functioning equivalent to global impairment. For self-initiated mobility, in and out of the bed sizable limitations were noted and substantial inability to transfer caused friction and shearing. Similarly, any exhaustion and fatigue were associated with delirium. For self-initiated grooming and dressing, the impairment was greater in the upper body. Within the nutritional domain, delirium affected self-initiated eating and drinking, the amount of food and fluids, energy and nutrient, as well as parenteral nutrition requirement. In delirious patients, the fluid demand was rather increased than decreased, tube feeding more often required and dysphagia occurred. For the elimination domain, urination was not affected - of note, most patients were catheterized, whereas abilities to initiate or control defecation were affected. SIGNIFICANCE OF RESULTS: Delirium was associated with sizable impairment in the level of functioning. These impairments could guide supportive interventions for delirious patients and perspectively implement nursing instruments for delirium screening.

MP2RAGE multispectral voxel-based morphometry in focal epilepsy.

We assessed the applicability of MP2RAGE for voxel-based morphometry. To this end, we analyzed its brain tissue segmentation characteristics in healthy subjects and the potential for detecting focal epileptogenic lesions (previously visible and nonvisible). Automated results and expert visual interpretations were compared with conventional VBM variants (i.e., T1 and T1 + FLAIR). Thirty-one healthy controls and 21 patients with focal epilepsy were recruited. 3D T1-, T2-FLAIR, and MP2RAGE images (consisting of INV1, INV2, and MP2 maps) were acquired on a 3T MRI. The effects of brain tissue segmentation and lesion detection rates were analyzed among single- and multispectral VBM variants. MP2-single-contrast gave better delineation of deep, subcortical nuclei but was prone to misclassification of dura/vessels as gray matter, even more than conventional-T1. The addition of multispectral combinations (INV1, INV2, or FLAIR) could markedly reduce such misclassifications. MP2 + INV1 yielded generally clearer gray matter segmentation allowing better differentiation of white matter and neighboring gyri. Different models detected known lesions with a sensitivity between 60 and 100%. In non lesional cases, MP2 + INV1 was found to be best with a concordant rate of 37.5%, specificity of 51.6% and concordant to discordant ratio of 0.60. In summary, we show that multispectral MP2RAGE VBM (e.g., MP2 + INV1, MP2 + INV2) can improve brain tissue segmentation and lesion detection in epilepsy.

Increased Functional MEG Connectivity as a Hallmark of MRI-Negative Focal and Generalized Epilepsy.

Epilepsy is one of the most prevalent neurological diseases with a high morbidity. Accumulating evidence has shown that epilepsy is an archetypical neural network disorder. Here we developed a non-invasive cortical functional connectivity analysis based on magnetoencephalography (MEG) to assess commonalities and differences in the network phenotype in different epilepsy syndromes (non-lesional/cryptogenic focal and idiopathic/genetic generalized epilepsy). Thirty-seven epilepsy patients with normal structural brain anatomy underwent a 30-min resting state MEG measurement with eyes closed. We only analyzed interictal epochs without epileptiform discharges. The imaginary part of coherency was calculated as an indicator of cortical functional connectivity in five classical frequency bands. This connectivity measure was computed between all sources on individually reconstructed cortical surfaces that were surface-aligned to a common template. In comparison to healthy controls, both focal and generalized epilepsy patients showed widespread increased functional connectivity in several frequency bands, demonstrating the potential of elevated functional connectivity as a common pathophysiological hallmark in different epilepsy types. Furthermore, the comparison between focal and generalized epilepsies revealed increased network connectivity in bilateral mesio-frontal and motor regions specifically for the generalized epilepsy patients. Our study indicated that the surface-based normalization of MEG sources of individual brains enables the comparison of imaging findings across subjects and groups on a united platform, which leads to a straightforward and effective disclosure of pathological network characteristics in epilepsy. This approach may allow for the definition of more specific markers of different epilepsy syndromes, and increased MEG-based resting-state functional connectivity seems to be a common feature in MRI-negative epilepsy syndromes.

Detecting age-related changes in skeletal muscle mechanics using ultrasound shear wave elastography.

Aging leads to a decline in muscle mass and force-generating capacity. Ultrasound shear wave elastography (SWE) is a non-invasive method to capture age-related muscular adaptation. This study assessed biceps brachii muscle (BB) mechanics, hypothesizing that shear elastic modulus reflects (i) passive muscle force increase imposed by length change, (ii) activation-dependent mechanical changes, and (iii) differences between older and younger individuals. Fourteen healthy volunteers aged 60-80 participated. Shear elastic modulus, surface electromyography, and elbow torque were measured at five elbow positions in passive and active states. Data collected from young adults aged 20-40 were compared. The BB passive shear elastic modulus increased from flexion to extension, with the older group exhibiting up to 52.58% higher values. Maximum elbow flexion torque decreased in extended positions, with the older group 23.67% weaker. Significant effects of elbow angle, activity level, and age on total and active shear elastic modulus were found during submaximal contractions. The older group had 20.25% lower active shear elastic modulus at 25% maximum voluntary contraction. SWE effectively quantified passive and activation-dependent BB mechanics, detecting age-related alterations at rest and during low-level activities. These findings suggest shear elastic modulus as a promising biomarker for identifying altered muscle mechanics in aging.

Shear wave elastography characterizes passive and active mechanical properties of biceps brachii muscle in vivo.

Mechanical characterization of individual muscles in their in vivo environment is not well studied. Shear wave elastography (SWE) as a non-invasive technique was shown to be promising in quantifying the local mechanical properties of skeletal muscles. This study aimed to investigate the mechanics of the biceps brachii muscle (BB) derived from SWE in relation to elbow joint position and contraction intensity during isometric contraction. 14 healthy, young subjects participated in the study and five different joint positions (60°-180° elbow angle) were investigated. Shear elastic modulus and surface electromyography (sEMG) of the BB and elbow torque were measured simultaneously, both in passive (i.e., resting) and active states during slow, sub-maximal isometric ramp contractions up to 25%, 50%, and 75% of the maximum voluntary contraction. At passive state, the shear elastic modulus of the BB increased with increasing elbow angle (p < 0.001). Maximum elbow flexion torque was produced at 60° and it decreased with increasing elbow angle (p = 0.001). During sub-maximal contractions, both elbow angle (p < 0.001) and contraction intensity (p < 0.001) had significant effects on the shear elastic modulus but only contraction intensity (p < 0.001) affected sEMG amplitude of the BB. Although torque was decreased at extended elbow positions (150°, 180°), higher active shear elastic modulus of BB muscle was found compared to flexed positions (60°, 90°). Linear regression of the BB sEMG amplitude over elbow torque showed good agreement for all joint positions (R2 between 0.69 and 0.89) while the linear agreement between shear elastic modulus of BB and elbow torque differed between flexed (R2 = 0.70 at 60° and R2 = 0.79 at 90°) and extended positions (with the lowest R2 = 0.57 at 150°). We conclude that using SWE, we can detect length-dependent mechanical changes of BB both in passive and active states. More importantly, SWE can be used to characterize active muscle properties in vivo. The present findings have critical importance for developing muscle stiffness as a measure of individual muscle force to validate muscle models and using SWE in clinical diagnostics.

Characterization of Muscle Weakness Due to Myasthenia Gravis Using Shear Wave Elastography.

Myasthenia gravis (MG) is often accompanied with muscle weakness; however, little is known about mechanical adaptions of the affected muscles. As the latter can be assessed using ultrasound shear wave elastography (SWE), this study characterizes the biceps brachii muscle of 11 patients with MG and compares them with that of 14 healthy volunteers. Simultaneous SWE, elbow torque and surface electromyography measurements were performed during rest, maximal voluntary contraction (MVC) and submaximal isometric contractions (up to 25%, 50% and 75% MVC) at different elbow angles from flexion to extension. We found that, with increasing elbow angle, maximum elbow torque decreased (p < 0.001), whereas muscle stiffness increased during rest (p = 0.001), MVC (p = 0.004) and submaximal contractions (p < 0.001). Muscle stiffness increased with increasing contraction intensities during submaximal contractions (p < 0.001). In comparison to the healthy cohort, muscle stiffness of MG patients was 2.1 times higher at rest (p < 0.001) but 8.93% lower in active state (75% MVC, p = 0.044). We conclude that (i) increased muscle stiffness shown by SWE during rest might be an indicator of MG, (ii) SWE reflects muscle weakness and (iii) SWE can be used to characterize MG muscle.

Generation of an induced pluripotent stem cell (iPSC) line from a patient with GEFS+ carrying a STX1B (p.Lys45delinsArgMetCysIleGlu and p.Leu46Met) mutation.

The STX1B gene encodes the presynaptic protein syntaxin-1B, which plays a major role in regulating fusion of synaptic vesicles. Mutations in STX1B are known to cause epilepsy syndromes, such as genetic epilepsies with febrile seizures plus (GEFS+). Here, we reprogrammed skin fibroblasts from a female patient affected by GEFS+ to human induced pluripotent stem cells (iPSCs). The patient carries an InDel mutation (c.133_134insGGATGTGCATTG; p.Lys45delinsArgMetCysIleGlu and c.135_136AC > GA; p.Leu46Met), located in the regulatory Habc-domain of STX1B. Successful reprogramming of cells was confirmed by a normal karyotype, expression of several pluripotency markers and the potential to differentiate into all three germ layers.

Influence of Root Post Materials and Aging on Fracture Strength and Marginal Gap Quality of Ceramic Crowns-An In Vitro Study.

The design of and materials for prosthodontic abutments and posts have significant influences on the fracture resistance of restored teeth. This in vitro study compared the fracture strength and marginal quality of full-ceramic crowns as a function of the inserted root posts via simulation of a five-year period of use. Test specimens were prepared from 60 extracted maxillary incisors using titanium L9 (A), glass-fiber L9 (B), and glass-fiber L6 (C) root posts. The circular marginal gap behavior, linear loading capacity, and material fatigue after artificial aging were investigated. The marginal gap behavior and material fatigue were analyzed using electron microscopy. The linear loading capacity of the specimens was investigated using the Zwick Z005 universal testing machine. None of the tested root post materials showed statistically significant differences in marginal width values (p = 0.921), except in the case of marginal gap location. For Group A, there was a statistically significant difference from the labial to the distal (p = 0.012), mesial (p = 0.000), and palatinal (p = 0.005). Similarly, Group B showed a statistically significant difference from the labial to the distal (p = 0.003), mesial (p = 0.000), and palatinal (p = 0.003). Group C showed a statistically significant difference from the labial to the distal (p = 0.001) and mesial (p = 0.009). Linear load capacity reached mean values of 455.8-537.7 N, and micro-cracks occurred after artificial aging, predominantly in Groups B and C. Through the chosen experimental design, it was shown that the root post material and root post length had no influence on the fracture strength of the test teeth before or after artificial aging. However, the marginal gap location depends on the root post material and its length, which is wider mesially and distally and also tends to be greater palatinally than labially.

Sponge EEG is equivalent regarding signal quality, but faster than routine EEG.

Objective: Emergency diagnostics, such as acquisition of an electroencephalogram (EEG), are of great diagnostic importance, but there is often a lack of experienced personnel. Wet active electrode sponge-based electroencephalogram (sp-EEG) systems can be applied rapidly and by inexperienced personnel. This makes them an attractive alternative to routine EEG (r-EEG) systems in these settings. Here, we examined the feasibility and signal quality of sp-EEG compared to r-EEG. Methods: In this case-control, single-blind, non-randomized study, EEG recordings using a sp- and a r-EEG system were performed in 18 individuals with a variety of epileptiform discharges and 11 healthy control subjects. The time was stopped until all electrodes in both systems displayed adequate skin-electrode impedances. The resulting 58 EEGs were visually inspected by 7 experienced, blinded neurologists. Raters were asked to score physiological and pathological graphoelements, and to distinguish between the different systems by visual inspection of the EEGs. Results: Time to signal acquisition for sp-EEG was significantly faster (4.8 min (SD 2.01) vs. r-EEG 13.3 min (SD 2.72), p < 0.001). All physiological and pathological graphoelements of all 58 EEGs could be identified. Raters were unable to distinguish between sp-EEG or r-EEG based on visual inspection of the EEGs alone. Conclusions: Sp-EEG represents a feasible alternative to r-EEG in emergency diagnostics or resource-limited settings. Significance: Given shortage of trained personnel or resources, the easy implementation and comparable quality of a novel sp-EEG system may increase general availability of EEG and thus improve patient care.

Discrimination of finger movements by magnetomyography with optically pumped magnetometers.

Optically pumped magnetometers (OPM) are quantum sensors that offer new possibilities to measure biomagnetic signals. Compared to the current standard surface electromyography (EMG), in magnetomyography (MMG), OPM sensors offer the advantage of contactless measurements of muscle activity. However, little is known about the relative performance of OPM-MMG and EMG, e.g. in their ability to detect and classify finger movements. To address this in a proof-of-principle study, we recorded simultaneous OPM-MMG and EMG of finger flexor muscles for the discrimination of individual finger movements on a single human participant. Using a deep learning model for movement classification, we found that both sensor modalities were able to discriminate finger movements with above 89% accuracy. Furthermore, model predictions for the two sensor modalities showed high agreement in movement detection (85% agreement; Cohen's kappa: 0.45). Our findings show that OPM sensors can be employed for contactless discrimination of finger movements and incentivize future applications of OPM in magnetomyography.

Alignment of magnetic sensing and clinical magnetomyography.

Neuromuscular diseases are a prevalent cause of prolonged and severe suffering for patients, and with the global population aging, it is increasingly becoming a pressing concern. To assess muscle activity in NMDs, clinicians and researchers typically use electromyography (EMG), which can be either non-invasive using surface EMG, or invasive through needle EMG. Surface EMG signals have a low spatial resolution, and while the needle EMG provides a higher resolution, it can be painful for the patients, with an additional risk of infection. The pain associated with the needle EMG can pose a risk for certain patient groups, such as children. For example, children with spinal muscular atrophy (type of NMD) require regular monitoring of treatment efficacy through needle EMG; however, due to the pain caused by the procedure, clinicians often rely on a clinical assessment rather than needle EMG. Magnetomyography (MMG), the magnetic counterpart of the EMG, measures muscle activity non-invasively using magnetic signals. With super-resolution capabilities, MMG has the potential to improve spatial resolution and, in the meantime, address the limitations of EMG. This article discusses the challenges in developing magnetic sensors for MMG, including sensor design and technology advancements that allow for more specific recordings, targeting of individual motor units, and reduction of magnetic noise. In addition, we cover the motor unit behavior and activation pattern, an overview of magnetic sensing technologies, and evaluations of wearable, non-invasive magnetic sensors for MMG.

Influence of Different Bracket Adhesive Systems on Enamel Demineralization-An In Vitro Study.

BACKGROUND: enamel demineralization is a common side effect of orthodontic therapy with fixed braces. The aim of the present in vitro study was to compare a conventional adhesive system and a modern adhesive system (APC Flash-Free [FF] technology) with regard to the demineralization of enamel by Streptococcus sobrinus (S. sobrinus). METHODS: this in vitro study included premolar teeth and compared APC FF adhesive brackets (Group A, n = 15) with conventional adhesive brackets (Group B, n = 15) from the same company. Specimens were incubated with a positive control group (PCG, n = 5) and a negative control group (NCG, n = 5) in an S. sobrinus suspension for three weeks. To evaluate the grade of enamel demineralization, the samples were analyzed using a polarizing microscope. RESULTS: the test specimens of group B with conventionally bonded bracket adhesive showed significantly greater (+10.8 µm) demineralization with regard to the penetration depth of the demineralization than the PCG (p = 0.012). Thus, there was a difference from group A with the new bracket adhesive of the FF brackets (+7.29 µm). Significantly, demineralization was more pronounced cervically than coronally in both groups, and it occurred cervically more frequently than grade 3 demineralization (p = 0.001). CONCLUSIONS: it seems plausible that new orthodontic bracket adhesives and the modern FF adhesive system positively contribute to the reduction in enamel demineralization during orthodontic treatment.

Multi-spectral diffusion MRI mega-analysis in genetic generalized epilepsy: Relation to outcomes.

BACKGROUND AND OBJECTIVES: Genetic generalized epilepsy (GGE) is the most common form of generalized epilepsy. Although individual patients with GGE typically present without structural alterations, group differences have been demonstrated in GGE and some GGE subtypes like juvenile myoclonic epilepsy (GGE-JME). Previous studies usually involved only small cohorts from single centers and therefore could not assess imaging markers of multiple GGE subtypes. METHODS: We performed a diffusion MRI mega-analysis in 192 participants consisting of 126 controls and 66 patients with GGE from four different cohorts and two different epilepsy centers. We applied whole-brain multi-site harmonization and analyzed fractional anisotropy (FA), as well as mean, radial and axial diffusivity (MD/RD/AD) to assess differences between controls, patients with GGE and the common GGE subtypes, i.e. GGE with generalized tonic-clonic seizures only (GGE-GTCS), GGE-JME and absence epilepsy (GGE-AE). We also analyzed relationships with patients' response to anti-seizure-medication (ASM). RESULTS: Relative to controls, we identified decreased anisotropy and increased RD in patients with GGE. We found no significant effects of disease duration, age of onset or seizure frequency on diffusion metrics. Patients with JME had increased MD and RD when compared to controls, while patients with GGE-GTCS showed decreased MD/AD when compared to controls. Compared to patients with GGE-AE, patients with GGE-GTCS had lower AD/MD. Compared to patients with GGE-GTCS, patients with GGE-JME had higher MD/RD and AD. Moreover, we found lower FA in patients with refractory when compared to patients with non-refractory GGE in the right cortico-spinal tract, but no significant differences in patients with active versus controlled epilepsy. DISCUSSION: We provide evidence that clinically defined GGE as a whole and GGE-subtypes harbor marked microstructural differences detectable with diffusion MRI. Moreover, we found an association between microstructural changes and treatment resistance. Our findings have important implications for future full-resolution multi-site studies when assessing GGE, its subtypes and ASM refractoriness.