Nonhomogeneous volume conduction effects affecting needle electromyography: an analytical and simulation study

2021 ◽  
Author(s):  
Xuesong Luo ◽  
Shaoping Wang ◽  
Seward B Rutkove ◽  
Benjamin Sanchez
Keyword(s):  
Electrical Properties ◽  
Neuromuscular Disorders ◽  
Electrical Potential ◽  
Neuromuscular Diseases ◽  
Field Potential ◽  
Element Model ◽  
Emg Activity ◽  
Electrode Position ◽  
Volume Conduction ◽  
Needle Electromyography

Abstract Objective: Needle electromyography (EMG) is used to study the electrical behavior of myofiber properties in patients with neuromuscular disorders. However, due to the complexity of electrical potential spatial propagation in nonhomogeneous diseased muscle, a comprehensive understanding of volume conduction effects remains elusive. Here, we develop a framework to study the conduction effect of extracellular abnormalities {and electrode positioning} on extracellular local field potential (LFP) recordings. Methods: The framework describes the macroscopic conduction of electrical potential in an isotropic, nonhomogeneous (i.e., two tissue) model. Numerical and finite element model simulations are provided to study the conduction effect in prototypical monopolar EMG measurements. Results: LFPs recorded are influenced in amplitude, phase and duration by the electrode position in regards to the vicinity of tissue with different electrical properties. Conclusion: The framework reveals the influence of multiple mechanisms affecting LFPs including changes in the distance between the source -- electrode and tissue electrical properties. Clinical significance: Our modeled predictions may lead to new ways for interpreting volume conduction effects on recorded EMG activity, for example in neuromuscular diseases that cause structural and compositional changes in muscle tissue. These change will manifest itself by changing the electric properties of the conductor media and will impact recorded potentials in the area of affected tissue.

The effects of well damage and completion designs on geo-electrical responses in mature wellbore environments

Geophysics ◽  
2021 ◽  
pp. 1-50
Author(s):  
Gungor D. Beskardes ◽  
Chester J. Weiss ◽  
Evan Um ◽  
Michael Wilt ◽  
Kris MacLennan
Keyword(s):  
Finite Element ◽  
Electrical Potential ◽  
Real Life ◽  
Element Model ◽  
Computational Effort ◽  
Real Surface ◽  
Well Completion ◽  
Geologic Storage ◽  
Well Damage ◽  
Electrical Responses

Well integrity is one of the major concerns in long-term geologic storage sites due to its potential risk for well leakage and groundwater contamination. Evaluating changes in electrical responses due to energized steel-cased wells has the potential to quantify and predict possible wellbore failures as any kind of breakage or corrosion along highly-conductive well casings will have an impact on the distribution of subsurface electrical potential. However, realistic wellbore-geoelectrical models that can fully capture fine scale details of well completion design and state of well damage at the field scale require extensive computational effort or can even be intractable to simulate. To overcome this computational burden while still keeping the model realistic, we utilize the Hierarchical Finite Element Method which represents electrical conductivity at each dimensional component (1-D edges, 2-D planes and 3-D cells) of a tetrahedra mesh. This allows us to consider well completion designs with real-life geometric scales and well systems with realistic, detailed, progressive corrosion and damage in our models. Here, we present a comparison of possible discretization approaches of a multi-casing completion design in the finite element model. The impacts of the surface casing length and the coupling between concentric well casings, as well as the effects of the degree and the location of well damage on the electrical responses are also examined. Finally, we analyze real surface electric field data to detect the wellbore integrity failure associated with damage.

Organ-on-a-chip technologies to study neuromuscular disorders: possibilities, limitations, and future hopes

2021 ◽  
Vol 33 (3) ◽  
pp. 261-267
Author(s):  
Marlen C. Lauffer
Keyword(s):  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Neuromuscular Disorders ◽  
Neuromuscular Diseases ◽  
Disease Mechanisms ◽  
Modeling Systems ◽  
Therapy Development ◽  
Organ On A Chip ◽  
Induced Pluripotent ◽  
Shed Light

Abstract Neuromuscular disorders are a heterogeneous group of diseases ranging from mild to devastating phenotypes depending on the disorder’s origin. Pathophysiologies for many of these disorders are not fully understood and efficient therapies are urgently needed. Recent advances in the field of induced pluripotent stem cells and organ-on-a-chip technologies have brought enormous improvement in modeling neuromuscular diseases. Even complex units, like the neuromuscular junction, can now be built, enabling researchers to study each component of the motor unit by itself or interacting with others, allowing the identification of disease mechanisms. This article aims to introduce these new modeling systems to study neuromuscular disorders and the possibilities of organ-on-a-chip platforms to shed light on disease pathologies and their use for therapy development.

Assessing the Motor Unit with Needle Electromyography

2009 ◽  
pp. 403-450 ◽  
Author(s):  
Devon I. Rubin
Keyword(s):  
Neuromuscular Junction ◽  
Peripheral Nerve ◽  
Motor Unit ◽  
Neuromuscular Diseases ◽  
Electric Activity ◽  
Great Sensitivity ◽  
Muscle Disease ◽  
Fine Needle ◽  
Needle Electromyography ◽  
Clinical Measures

Virtually all primary neuromuscular diseases result in changes in the electric activity recorded from muscle fibers. These changes can best be depicted using fine needle electrodes inserted into the muscle to record spontaneous and voluntary EMG. Thus, EMG can be used to distinguish among lower motor neuron, peripheral nerve, neuromuscular junction, and muscle disease with great sensitivity and some specificity. The sensitivity is usually greater than clinical measures; specificity in identifying the cause of the disease often requires muscle biopsy or other clinical measures. Although EMG is somewhat uncomfortable for patients because needles need to be inserted into the muscles, it generally is well tolerated by patients and provides a rapid, efficient means of testing the motor unit.

Effect of calcium on ion transport and electrical properties of tracheal epithelium

1978 ◽  
Vol 44 (6) ◽  
pp. 900-904 ◽  
Author(s):  
M. G. Marin ◽  
M. M. Zaremba
Keyword(s):  
Electrical Properties ◽  
Ion Transport ◽  
Calcium Concentration ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Tracheal Epithelium ◽  
Electrical Potential Difference ◽  
Tracheal Lumen

Active transport of Cl- toward the tracheal lumen and Na+ away from the lumen creates an electrical potential difference across dog tracheal epithelium. This study examined in vitro the effect of varying calcium concentration in the bathing media on the ion transport and electrical properties of dog tracheal epithelium. In six pairs of epithelia, changing calcium concentration from 1.9 to 0 mM resulted in a significant decrease in electrical resistance, from 318 +/- 36 to 214 +/- 24 omega.cm2. Short-circuit current and net Cl- and Na+ fluxes measured under short-circuit conditions were not changed significantly. Changing calcium concentration from 1.9 to 10 mM resulted in no significant change from control in the electrical properties nor in net Cl- and Na+ fluxes (short-circuit conditions). Histamine (10(-4) M) produced a significantly smaller increase in short-circuit current in 0 than in 1.9 mM Ca2+ (+5 +/- 2 vs. +12 +/- 2 microamperemeter/cm2). However, electrical changes were not significantly different in 1 or 10 mM Ca2+. These results indicate that calcium lack increased permeability of tracheal epithelium and that the increase in short-circuit current due to histamine depended in part on calcium.

scholarly journals Ten-year experience with standardized non-operating room anesthesia with Sevoflurane for MRI in children affected by neuropsychiatric disorders

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Silvia Mongodi ◽  
Gaia Ottonello ◽  
Raffaelealdo Viggiano ◽  
Paola Borrelli ◽  
Simona Orcesi ◽  
...  
Keyword(s):  
Risk Factors ◽  
Clinical Judgment ◽  
Statistical Significance ◽  
Neuromuscular Disorders ◽  
Univariate Analysis ◽  
Neuromuscular Diseases ◽  
Neuropsychiatric Disorders ◽  
University Hospital ◽  
Respiratory Complications ◽  
Asa Score

Abstract Background Children require anesthesia for MRI to maintain immobility and reduce discomfort; clear indications about the best anesthesiologic management are lacking and each center developed its own protocol. Moreover, children with neuropsychiatric disorders more likely require sedation and are described in literature as more prone to general and respiratory complications. Aim of this study was to analyze the applicability of a sevoflurane-based approach, to describe general and respiratory complications and to identify risk factors in a pediatric neuropsychiatric population. Methods Retrospective cohort study, university Hospital (January 2007–December 2016). All the 1469 anesthesiologic records of children addressed from Neuropsychiatric Unit to undergo MRI under general anesthesia were analyzed; 12 patients equal or older than 18-year-old were excluded. We identified post-hoc nine macro-categories: static encephalopathies, metabolic/evolutive encephalopathies, epileptic encephalopathies, neuromuscular diseases, autistic spectrum disorders, migraine, psychiatric disorders, intellectual disabilities, others. A logistic regression model for events with low frequency (Firth’s penalized likelihood approach) was carried out to identify the mutually adjusted effect among endpoints (complications) and the independent variables chosen on the basis of statistical significance (univariate analysis, p ≤ 0.05) and clinical judgment. Results Of 1457 anesthesiologic records (age 4.0 (IQR 2.0 to 7.0) year-old, males 891 (61.2%), weight 17.0 (IQR 12.0 to 24.9) kg), 18 were cancelled for high anesthesiologic risk, 50 were cooperative, 1389 were anesthetized. A sevoflurane-based anesthesia was feasible in 92.3%; these patients required significantly less mechanical ventilation (8.6 vs. 16.2%; p = 0.012). Complications’ rate was low (6.2%; 3.1% respiratory). The risk for general complications increases with ASA score > 1 (OR 2.22, 95 CI% 1.30 to 3.77, p = 0.003), male sex (OR 1.73, 95% CI 1.07 to 2.81, p = 0.025), multi-drug anesthesia (OR 2.98, 95 CI% 1.26 to 7.06, p = 0.013). For respiratory complications, it increases with ASA score > 1 (OR 2.34, 95 CI% 1.19 to 4.73, p = 0.017), autumn-winter (OR 2.01, 95 CI% 1.06 to 3.78, p = 0.030), neuromuscular disorders (OR 3.18, 95 CI% 1.20 to 8.41, p = 0.020). We had no major complications compromising patients’ outcome or requiring admission to ICU. Conclusions Sevoflurane anesthesia is feasible and safe for children affected by neuropsychiatric disorders undergoing MRI. Specific risk factors for general and respiratory complications should be considered.

Neuromuscular Disorders and Anesthesia

2018 ◽  
Author(s):  
Mariel Manlapaz ◽  
Perin Kothari
Keyword(s):  
Perioperative Management ◽  
Neuromuscular Disorders ◽  
Neuromuscular Diseases ◽  
Tonic Contraction ◽  
Endocrine Dysfunction ◽  
Muscle Involvement ◽  
Disease States ◽  
Anesthetic Drugs ◽  
Anesthetic Considerations ◽  
The Right

The various neuromuscular diseases present with different airway, cardiovascular, pulmonary, and anesthetic considerations. It is useful to categorize these different diseases into nerve, neuromuscular junction, and primary muscle diseases. Understanding their pathophysiology is paramount in choosing the right anesthetic drugs (for example, depolarizing versus nondepolarizing and regional versus general anesthesia). Knowing their manifestations such as autonomic dysfunction, skeletal/cardiac/smooth/bulbar muscle involvement, or tendency for tonic contraction, allows for expectant perioperative management. Finally appreciating their association with certain disease states such as malignant hyperthermia or endocrine dysfunction can prevent complications. A brief review of myotonic dystrophy is presented here, followed by a brief summary of anesthetic considerations for various neuromuscular diseases.

scholarly journals Timed motor function tests capacity in healthy children

2015 ◽  
Vol 101 (2) ◽  
pp. 147-151 ◽  
Author(s):  
Aline Chacon Pereira ◽  
Márcia Gonçalves Ribeiro ◽  
Alexandra Prufer de Queiroz Campos Araújo
Keyword(s):  
Motor Function ◽  
Neuromuscular Disorders ◽  
Neuromuscular Diseases ◽  
Vital Signs ◽  
Healthy Children ◽  
Cross Sectional ◽  
Motor Functions ◽  
Function Tests ◽  
Measured Time ◽  
Registration Number

ObjectiveMotor function tests are used clinically and in research in children, particularly in those with neuromuscular disorders. Timed function tests are recommended in the follow-up of patients with neuromuscular disorders. This study was designed to know how healthy children perform on simple timed motor function tests.Material and methodsIn a cross-sectional observational study, 345 children aged 2–12 years, followed at the Federal University of Rio de Janeiro's Institute of Paediatric, were evaluated. To be eligible they had to have acquired independent walking before the age of 14 months, be able to cope and willing to participate in the study. Anthropometric and vital signs were verified, as well as contact with smokers. The following timed motor function tests were measured: time to rise from the floor (TRF), time to walk 10 meters (10MWT) and time to run 10 meters (10MRT).ResultsImprovement in time to perform those motor functions was found to occur in healthy preschool children. Stabilisation of mean times for those motor functions was seen thereafter: TRF of 1.2 s, 10MWT of 10 s and 10MRT of 5 s.ConclusionsWalking and rising speed improve with age in preschoolers, as expected, and is shown to occur up to a plateau level. Our findings for the 10MWT, 10MRT and TRF are in line with those published in 2008 for the 6 minute walk test (6MWT). The motor functions used in the present study require less time and space than the ones in the 6MWT. They should be considered more universally applicable. Those tests could be used in childcare clinics as a screening for motor disorders such as the neuromuscular diseases.Trial registration number1.098.302.

scholarly journals Motor Chip: A Comparative Genomic Hybridization Microarray for Copy-Number Mutations in 245 Neuromuscular Disorders

2011 ◽  
Vol 57 (11) ◽  
pp. 1584-1596 ◽  
Author(s):  
Giulio Piluso ◽  
Manuela Dionisi ◽  
Francesca Del Vecchio Blanco ◽  
Annalaura Torella ◽  
Stefania Aurino ◽  
...  
Keyword(s):  
Comparative Genomic Hybridization ◽  
Copy Number ◽  
Neuromuscular Disorders ◽  
Neuromuscular Diseases ◽  
Copy Number Variations ◽  
Comparative Genomic ◽  
Specific Gene ◽  
Disease Genes ◽  
Genomic Hybridization ◽  
Gene Coverage

BACKGROUND Array-based comparative genomic hybridization (aCGH) is a reference high-throughput technology for detecting large pathogenic or polymorphic copy-number variations in the human genome; however, a number of quantitative monogenic mutations, such as smaller heterozygous deletions or duplications, are usually missed in most disease genes when proper multiplex ligation-dependent probe assays are not performed. METHODS We developed the Motor Chip, a customized CGH array with exonic coverage of 245 genes involved in neuromuscular disorders (NMDs), as well as 180 candidate disease genes. We analyzed DNA samples from 26 patients with known deletions or duplications in NMDs, 11 patients with partial molecular diagnoses, and 19 patients with a clinical diagnosis alone. RESULTS The Motor Chip efficiently confirmed and refined the copy-number mutations in all of the characterized patients, even when only a single exon was involved. In noncharacterized or partially characterized patients, we found deletions in the SETX (senataxin), SGCG [sarcoglycan, gamma (35kDa dystrophin-associated glycoprotein)], and LAMA2 (laminin, alpha 2) genes, as well as duplications involving LAMA2 and the DYSF [dysferlin, limb girdle muscular dystrophy 2B (autosomal recessive)] locus. CONCLUSIONS The combination of exon-specific gene coverage and optimized platform and probe selection makes the Motor Chip a complementary tool for molecular diagnosis and gene investigation in neuromuscular diseases.

scholarly journals CSF Diagnostics: A Potentially Valuable Tool in Neurodegenerative and Inflammatory Disorders Involving Motor Neurons: A Review

Diagnostics ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1522
Author(s):  
Karsten Krause ◽  
Maximilian Wulf ◽  
Paula Sommer ◽  
Katalin Barkovits ◽  
Matthias Vorgerd ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Muscular Atrophy ◽  
Neurological Diseases ◽  
Neuromuscular Disorders ◽  
Disease Onset ◽  
Neuromuscular Diseases ◽  
Promising Alternative ◽  
Alternative Techniques ◽  
Subordinate Role ◽  
Lateral Sclerosis

Cerebrospinal fluid (CSF) diagnostics has emerged as a valid tool for a variety of neurological diseases. However, CSF diagnostics has been playing a subordinate role in the diagnosis of many neurological conditions. Thus, in the multitude of neuromuscular diseases in which motor neurons are affected, a CSF sample is rarely taken routinely. However, CSF diagnostics has the potential to specify the diagnosis and monitor the treatment of neuromuscular disorders. In this review, we therefore focused on a variety of neuromuscular diseases, among them amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and spinal muscular atrophy (SMA), for which CSF diagnostics has emerged as a promising option for determining the disease itself and its progression. We focus on potentially valuable biomarkers among different disorders, such as neurofilaments, cytokines, other proteins, and lipids to determine their suitability, differentiating between different neurological disorders and their potential to determine early disease onset, disease progression, and treatment outcome. We further recommend novel approaches, e.g., the use of mass spectrometry as a promising alternative techniques to standard ELISA assays, potentially enhancing biomarker significance in clinical applications.

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