CutFEM forward modeling for EEG source analysis.

Introduction: Source analysis of Electroencephalography (EEG) data requires the computation of the scalp potential induced by current sources in the brain. This so-called EEG forward problem is based on an accurate estimation of the volume conduction effects in the human head, represented by a partial differential equation which can be solved using the finite element method (FEM). FEM offers flexibility when modeling anisotropic tissue conductivities but requires a volumetric discretization, a mesh, of the head domain. Structured hexahedral meshes are easy to create in an automatic fashion, while tetrahedral meshes are better suited to model curved geometries. Tetrahedral meshes, thus, offer better accuracy but are more difficult to create. Methods: We introduce CutFEM for EEG forward simulations to integrate the strengths of hexahedra and tetrahedra. It belongs to the family of unfitted finite element methods, decoupling mesh and geometry representation. Following a description of the method, we will employ CutFEM in both controlled spherical scenarios and the reconstruction of somatosensory-evoked potentials. Results: CutFEM outperforms competing FEM approaches with regard to numerical accuracy, memory consumption, and computational speed while being able to mesh arbitrarily touching compartments. Discussion: CutFEM balances numerical accuracy, computational efficiency, and a smooth approximation of complex geometries that has previously not been available in FEM-based EEG forward modeling.

Utility of Inter-Frequency Amplitude Ratio of Vestibular-Evoked Myogenic Potentials in Identifying Meniere's Disease: A Systematic Review and Meta-Analysis.

OBJECTIVES: A recently devised parameter of vestibular-evoked myogenic potential (VEMP) based on the principles of frequency tuning is the inter-frequency amplitude ratio (IFAR). It refers to the ratio of the amplitude of 1000 Hz tone burst evoked VEMP to 500 Hz evoked tone burst. A pathology like Meniere's disease changes the frequency response and alters the frequency tuning of the otolith organs. Because IFAR is based on the principle of frequency tuning of VEMP, it is likely to help identify Meniere's disease. Few studies in the last decade have investigated the utility of IFAR in identifying Meniere's disease. However, a systematic review and a meta-analysis on IFAR in Meniere's disease are lacking. The present study investigates whether the IFAR of VEMP helps identify Meniere's disease and differentiates it from healthy ears and other vestibular pathologies. DESIGN: The present study is a systematic review and a meta-analysis. The studies investigating the IFAR of cervical and ocular VEMPs in Meniere's disease, healthy controls, and other vestibular pathologies were searched across research databases such as PubMed, Science Direct, and Scopus. The search strategy was developed using the PICO (population, intervention, comparison, and outcomes) format, and Medical Subject Headings (MeSH) terms and Boolean operators were employed. The systematic review was performed using the Rayyan software, whereas the Review Manager software was used to carry out the meta-analysis. A total of 16,605 articles were retrieved from the databases. After the duplicate removal, 2472 articles remained. These were eliminated using title screening, abstract screening, and full-length inspections. A total of nine articles were found eligible for quality assessment and meta-analysis, and the New Castle-Ottawa Scale was used for quality assessment. After the data extraction, 24 six articles were found to have the desired data format for the meta-analysis. RESULTS: The results showed significantly higher IFAR in the affected ears of individuals in the Meniere's disease group than in the control group's unaffected ears. There was no significant difference between the unaffected ears of individuals in the Meniere's disease group and the ears of the control group. The only study on Meniere's disease and benign paroxysmal positional vertigo found significantly larger ocular VEMP IFAR in ears with Meniere's disease than in benign paroxysmal positional vertigo. CONCLUSIONS: This systematic review and meta-analysis found IFAR efficient in differentiating Meniere's disease from healthy controls. We also found an enhanced IFAR as a potential marker for Meniere's disease. However, more investigations are needed to confirm the utility of an enhanced IFAR value in the exclusive identification of Meniere's disease.

Lesión cerebral post paro cardiaco: aspectos médicos, éticos y legales / Brain injury after cardiac arrest: Medical, ethical and legal issues disorder

RESUMEN Los sobrevivientes de la reanimación cardiopulmonar posterior a un paro cardiaco pueden tener un amplio rango de desenlaces y van desde recuperación neurológica completa, estado de vigilia sin respuesta, compromiso cognoscitivo diverso o la muerte. La lesión del tejido cerebral se presenta inmediatamente después del paro cardíaco, durante la reanimación y al retornar la circulación espontánea. La severidad y duración de la noxa isquémica determinarán el devenir neurológico. El examen clínico es el punto de partida en el abordaje multimodal del neuropronóstico. Se debe complementar con electroencefalograma, potenciales evocados somatosensoriales, neuroimágenes y biomar-cadores séricos. Entre un 10 a 15% de los pacientes con lesión cerebral posterior al paro cardiaco evolucionan hacia muerte por criterios neurológicos y son potenciales candidatos a la donación de órganos. Un retiro temprano de las terapias de sostenimiento de vida puede malograr la posibilidad de un potencial donante de órganos. Se puede estimar de manera temprana qué pacientes tienen mayor riesgo de evolucionar a muerte por criterios neurológicos. El neurólogo tiene un papel protagónico en el manejo de pacientes con lesión cerebral post paro cardiaco y sus decisiones tienen implicaciones éticas y legales.

ABSTRACT People who survive cardiopulmonary resuscitation (CPR) after cardiac arrest, have a wide range of outcomes including complete neurological recovery, coma, compromised cognitive function and death. Injury of the brain parenchyma starts immediately after a cardiac arrest, during CPR and return of spontaneous circulation. The severity of the ischemic injury will define the neurological outcome. The first step needed to determine a neurological prognosis is the clinical exam, with the help of electroencephalography, somatosensory evoked potentials, neuroimaging, and serum biomarkers. Between 10 and 15% of patients with brain injury after a cardiac arrest, develop brain death and become potential candidates for organ donation. A premature withdrawal of vital support can hamper the possibility of organ donation. The patients with higher risk of developing brain death can be identified early based on neurological criteria. The neurologist has a major role in the approach of patients with brain injury after cardiac arrest and the decision making with legal and ethical consequences.

Vestibular assessment in children aged zero to twelve years: an integrative review.

OBJECTIVE: To describe the main vestibular assessment tests performed in children aged zero to twelve years and the main causes of referral for vestibular assessment. METHODS: The review was guided by the following question: What are the main vestibular assessment tests performed in children aged zero to twelve years and the main causes of referral for vestibular assessment? The PVO strategy was used, being defined as: Population (P) - newborns and children; study Variable (V) - causes of referral for vestibular assessment; study Outcome (O): the main vestibular assessment tests and the main findings. This study was carried out using the main available databases in the months of July, August and September 2021, with no restrictions regarding language and publication date, namely: PubMed, Web of Science, Scientific Electronic Library Online (SciELO), Latin-American and Caribbean Literature in Health Sciences (LILACS), ScienceDirect, Cochrane Library and Embase. The descriptors were obtained from the MeSH database: newborn, infant, child, children, vestibular screening, vestibular infant screening, vestibular newborn screening, test, vestibular function, vestibular function test. RESULTS: A total of 7,078 studies were identified. After reading the titles and abstracts, 107 of them were selected, with 101 remaining after the exclusion of duplicates. After the full-text reading, 31 articles were included. It was observed that the most frequently used tests were: rotational tests, caloric stimulation and cervical vestibular evoked myogenic potential and the main causes of referral for vestibular evaluation were hearing loss and vestibular screening. CONCLUSION: The main tests for vestibular screening and/or assessment of children aged zero to twelve years are the rotary chair testing, caloric stimulation and cervical-vestibular evoked myogenic potential. Consequently, performing these procedures is extremely important, since the presence of vestibular dysfunction is quite common in the studied population.

The effect of cochlear implant surgery on vestibular function in adults: A meta-analysis study.

Issue: The findings in literature indicate inconsistency in the complications caused by the implant of electrodes in the cochlea; vestibular alterations and balance disorders are mentioned as the most likely. Purpose: To evaluate, in literature, through the results of multiple vestibular function tests, the effects of cochlear implant surgery on postural stability in adult patients and to analyze. Hypothesis: From the PICO strategy, where the Population focuses on adults, Intervention is cochlear implant surgery, Comparisons are between implanted patients, and Outcomes are the results of the assessment of cochlear function, the research question was formulated: Are there deficits in vestibular function in adults undergoing cochlear implant placement? Method: Systematic review based on cohort, case-control, and cross-sectional observational studies. Information sources: Databases between 1980 and 2021, namely, PubMed, Cinahl, Web Of Science, Cochrane, and Scopus. Search strategy using Mesh terms: "Adult," "Cochlear Implant," "Postural Balance," "Posturography," "Cochlear Implant," "Dizziness," "Vertigo," "Vestibular Functional Tests,"and "Caloric Tests." Populational inclusion criteria: studies with adult patients; intervention: cochlear implant placement surgery; comparison: analysis of a vestibular function with vestibular test results and pre- and postoperative symptoms; outcome: studies with at least one of the vestibular function tests, such as computerized vectoelectronystagmography (VENG), vestibular-evoked myogenic potentials (VEMPs), caloric test, video head impulse test (VHIT), head impulse test (HIT), videonystagmography, (VNG) and static and dynamic posturography. Exclusion criteria: studies without records of pre- and postoperative data collection and studies with populations under 18 years of age. Screening based on the reading of abstracts and titles was performed independently by two reviewers. In the end, with the intermediation of a third reviewer, manuscripts were included. Risk of bias analysis, performed by two other authors, occurred using the JBI "Critical Appraisal Checklist." Results: Of the 757 studies, 38 articles met the inclusion criteria. VEMP was the most commonly used test by the studies (44.7%), followed by the caloric test (36.8%) and vHIT (23.6%). Most studies performed more than one test to assess vestibular function. Conclusion: Among all vestibular tests investigated, the deleterious effects on vestibular function after cochlear implant surgery were detected with statistical significance (P < 0.05) using VEMP and caloric test. Comparing abnormal and normal results after implant surgery, the vestibular apparatus was evaluated as having abnormal results after cochlear implant surgery only in the VEMP test. The other tests analyzed maintained a percentage mostly considered normal results. Systematic review registration: identifier: CRD42020198872.

Assessing the Capabilities of Transcranial Magnetic Stimulation (TMS) to Aid in the Removal of Brain Tumors Affecting the Motor Cortex: A Systematic Review.

Introduction: The brain tumor is frequently related to severe motor impairment and impacts the quality of life. The corticospinal tract can sometimes be affected depending on the type and size of the neoplasm, so different tools can evaluate motor function and connections. It is essential to organize surgical procedures and plan the approach. Functional motor status is mapped before, during, and after surgery. Studying corticospinal tract status can help map the functional areas, predict postoperative outcomes, and help the decision, reducing neurological deficits, aiming to preserve functional networks, using the concepts of white matters localization and fibbers connections. Nowadays, there are new techniques that provide functional information regarding the motor cortex, such as transcranial magnetic stimulation (TMS), direct cortical stimulation (DCS), and navigated TMS (nTMS). These tools can be used to plan a customized surgical strategy and the role of motor evoked potentials (MEPs) is well described during intra-operative, using intraoperative neuromonitoring. MEPs can help to localize primary motor areas and delineate the cut-off point of resection in real-time, using direct stimulation. In the post-operative, the MEP has increased your function as a predictive marker of permanent or transitory neurological lesion marker. Methods: Systematic review performed in MEDLINE via PUBMED, EMBASE, and SCOPUS databases regarding the post-operative assessment of MEP in patients with brain tumors. The search strategy included the following terms: (("Evoked Potentials, Motor"[Mesh]) AND "Neoplasms"[Mesh]) AND "Transcranial Magnetic Stimulation"[Mesh] AND "Brain Tumor"[Mesh]), the analysis followed the PRISMA guidelines for systematic reviews, the review spanned until 06/04/2021, inclusion criteria were studies presenting confirmed diagnosis of brain tumor (primary or metastatic), patients >18 y/o, using TMS, Navigated TMS, and/or Evoked Potentials as tools in preoperative planning or at the intra-operative helping the evaluation of the neurological status of the motor cortex, articles published in peer-reviewed journals, and written in English or Portuguese. Results: A total of 38 studies were selected for this review, of which 14 investigated the potential of nTMS to predict the occurrence of motor deficits, while 25 of the articles investigated the capabilities of the nTMS technique in performing pre/intraoperative neuro mapping of the motor cortex. Conclusion: Further studies regarding motor function assessment are needed and standardized protocols for MEPs also need to be defined.

Normative and Pathological Ranges of Cervical Vestibular Evoked Myogenic Potentials in Normal Subjects and Patients with Complete Compensated Unilateral Vestibular Loss: A Cross Sectional Study.

To know the normative ranges of VEMP response metrics in healthy young adults. To know the pathological cutoff of VEMP metrics in unilateral vestibular loss patients. To compare our VEMP metrics with the normative values of other studies from the western world. Prospective cross-sectional study. Tertiary care audiovestibular laboratory. 30 healthy subjects and 15 cases with a unilateral complete compensated loss. Various VEMP parameters-p1 latency, n1 latency, p1-n1 amplitude and Interaural asymmetry ratio (IAR) were entered into databases and analyzed. We compared our parameters with the most cited scientific data on VEMP available in the PubMed database, and we analyzed the results. 90% of controls and 80% of cases got VEMP responses at 95 dB HL threshold, 500 Hz with subject/patient placed in sitting upright with head turned to opposite side position. The normative data of VEMP response metrics in young adults for p1, n1 latencies, p1-n1 amplitude, and IAR are 13 ± 2 ms, 21 ± 2 ms, 91 ± 33 uV, and 9.25 ± 7.3, respectively. As the VEMP test has 100% sensitivity and 100% (95% CI 87-100%) negative predictive value in detecting the saccular dysfunction, we recommend the VEMP test as a mandatory tool in the vestibular test battery. There is no statistically significant difference in various VEMP parameters between the control and normal sides of the case group.

Association between autism spectrum disorder and changes in the central auditory processing in children.

OBJECTIVE: To verify the scientific evidence on the association between Autistic Spectrum Disorder and Central Auditory Processing Disorder in children, aiming to answer the following research question: What is the association between Autistic Spectrum and Alteration of Auditory Processing in Children? METHODS: Studies were chosen through the combination based on the Medical Subject Heading Terms (MeSH): [(auditory processing) and (children) and (autism) and (neurological disorders)]. The MEDLINE (PubMed), LILACS, and SciELO databases were used. The analyzed papers covered a ten-year period, from 2010 to 2020. We selected descriptive, cross-sectional, cohort, and case studies. We evaluated the quality of the papers, which had a minimum score of six in the modified scale of the literature. RESULTS: 126 papers were retrieved after the exclusion phase, and 17 of them followed the inclusion criteria. Only two papers answered the guiding question with audiological results. CONCLUSIONS: Patients diagnosed with autistic spectrum disorder may have disturbance central auditory processing, considering that changes were found both in absolute and interpeak latencies in the brainstem evoked response audiometry, as well as in latency and laterality of the N1c wave amplitude. In addition, there were changes in the assessment behavioral auditory processing. Thus, disturbance central auditory processing is common in children with autistic spectrum disorder.

The effect of experimental and clinical musculoskeletal pain on spinal and supraspinal projections to motoneurons and motor unit properties in humans: A systematic review.

BACKGROUND AND OBJECTIVE: Numerous studies have examined the influence of pain on spinal reflex excitability, motor unit behaviour and corticospinal excitability. Nevertheless, there are inconsistencies in the conclusions made. This systematic review sought to understand the effect of pain on spinal and supraspinal projections to motoneurons and motor unit properties by examining the influence of clinical or experimental pain on the following three domains: H-reflex, corticospinal excitability and motor unit properties. DATABASES AND DATA TREATMENT: MeSH terms and preselected keywords relating to the H-reflex, motor evoked potentials and motor unit decomposition in chronic and experimental pain were used to perform a systematic literature search using Cumulative Index of Nursing and Allied Health Literature (CINAHL), Excerpta Medica dataBASE (EMBASE), Web of Science, Medline, Google Scholar and Scopus databases. Two independent reviewers screened papers for inclusion and assessed the methodological quality using a modified Downs and Black risk of bias tool; a narrative synthesis and three meta-analyses were performed. RESULTS: Sixty-one studies were included, and 17 different outcome variables were assessed across the three domains. Both experimental and clinical pain have no major influence on measures of the H-reflex, whereas experimental and clinical pain appeared to have differing effects on corticospinal excitability. Experimental pain consistently reduced motor unit discharge rate, a finding which was not consistent with data obtained from patients. The results indicate that when in tonic pain, induced via experimental pain models, inhibitory effects on motoneuron behaviour were evident. However, in chronic clinical pain populations, more varied responses were evident likely reflecting individual adaptations to chronic symptoms. SIGNIFICANCE: This is a comprehensive systematic review and meta-analysis which synthesizes evidence on the influence of pain on spinal and supraspinal projections to motoneurons and motor unit properties considering measures of the H-reflex, corticospinal excitability and motor unit behaviour. The H-reflex is largely not influenced by the presence of either clinical or experimental pain. Whilst inhibitory effects on corticospinal excitability and motor unit behaviour were evident under experimental pain conditions, more variable responses were observed for people with painful musculoskeletal disorders.

Association between autism spectrum disorder and changes in the central auditory processing in children

SUMMARY OBJECTIVE: To verify the scientific evidence on the association between Autistic Spectrum Disorder and Central Auditory Processing Disorder in children, aiming to answer the following research question: What is the association between Autistic Spectrum and Alteration of Auditory Processing in Children? METHODS: Studies were chosen through the combination based on the Medical Subject Heading Terms (MeSH): [(auditory processing) and (children) and (autism) and (neurological disorders)]. The MEDLINE (PubMed), LILACS, and SciELO databases were used. The analyzed papers covered a ten-year period, from 2010 to 2020. We selected descriptive, cross-sectional, cohort, and case studies. We evaluated the quality of the papers, which had a minimum score of six in the modified scale of the literature. RESULTS: 126 papers were retrieved after the exclusion phase, and 17 of them followed the inclusion criteria. Only two papers answered the guiding question with audiological results. CONCLUSIONS: Patients diagnosed with autistic spectrum disorder may have disturbance central auditory processing, considering that changes were found both in absolute and interpeak latencies in the brainstem evoked response audiometry, as well as in latency and laterality of the N1c wave amplitude. In addition, there were changes in the assessment behavioral auditory processing. Thus, disturbance central auditory processing is common in children with autistic spectrum disorder.

Admittance Method for Estimating Local Field Potentials Generated in a Multi-Scale Neuron Model of the Hippocampus.

Significant progress has been made toward model-based prediction of neral tissue activation in response to extracellular electrical stimulation, but challenges remain in the accurate and efficient estimation of distributed local field potentials (LFP). Analytical methods of estimating electric fields are a first-order approximation that may be suitable for model validation, but they are computationally expensive and cannot accurately capture boundary conditions in heterogeneous tissue. While there are many appropriate numerical methods of solving electric fields in neural tissue models, there isn't an established standard for mesh geometry nor a well-known rule for handling any mismatch in spatial resolution. Moreover, the challenge of misalignment between current sources and mesh nodes in a finite-element or resistor-network method volume conduction model needs to be further investigated. Therefore, using a previously published and validated multi-scale model of the hippocampus, the authors have formulated an algorithm for LFP estimation, and by extension, bidirectional communication between discretized and numerically solved volume conduction models and biologically detailed neural circuit models constructed in NEURON. Development of this algorithm required that we assess meshes of (i) unstructured tetrahedral and grid-based hexahedral geometries as well as (ii) differing approaches for managing the spatial misalignment of current sources and mesh nodes. The resulting algorithm is validated through the comparison of Admittance Method predicted evoked potentials with analytically estimated LFPs. Establishing this method is a critical step toward closed-loop integration of volume conductor and NEURON models that could lead to substantial improvement of the predictive power of multi-scale stimulation models of cortical tissue. These models may be used to deepen our understanding of hippocampal pathologies and the identification of efficacious electroceutical treatments.

Morfología de los potenciales evocados auditivos de latencia tardía P300 y su rol en la evaluación de la conducta suicida / Morphology of auditory evoked potentials, and its role in the evaluation of suicidal behavior

El suicidio es un problema de salud a nivel mundial, siendo la conducta suicida uno de los predictores de mortalidad por suicidio; sin embargo, su valoración aún sigue siendo compleja. Aunque la cantidad de literatura que ha abordado distintas perspectivas de la conducta suicida es abundante, se requiere ahondar en nuevos métodos que permitan una valoración rápida y objetiva de ésta, proporcionando a los clínicos y pacientes, un sistema de evaluación que registre los cambios de estados emocionales de manera dinámica. El objetivo de este manuscrito fue proporcionar una visión general de la morfología de los potenciales evocados auditivos de latencia tardía p300 y su rol en la evaluación de la conducta suicida.

Suicide is a global health problem, with suicidal behavior being one of the predictors of suicide mortality; however, its assessment is still complex. Although the amount of literature that has addressed different perspectives of suicidal behavior is abundant, it is necessary to deepen new methods that allow a rapid and objective assessment of it, providing clinicians and patients with an evaluation system that allows changes in emotional state to be recorded dynamically. The aim of this manuscript was to provide an overview of morphological patterns of auditory evoked potential P300 latency late in the assessment of suicidal behavior.

Vestibular evoked myogenic potentials in the prognosis of sudden hearing loss - a systematic review / O potencial evocado miogênico vestibular no prognóstico da surdez súbita - uma revisão sistemática

Abstract Introduction: Sudden hearing loss is an otorhinolaryngological emergency that often leads to severe damage to the auditory and vestibular function. The vestibular evoked myogenic potential is a test that allows a noninvasive evaluation of the otolithic system function and vestibulospinal and vestibulo-ocular pathways. Objective: To evaluate the importance of vestibular evoked myogenic potential in determining the prognosis of patients with sudden hearing loss. Methods: A search for articles published up to December 2018 was performed in the PubMed, Cochrane, VHL and LILACS databases using MeSH descriptors. Retrospective and prospective articles were included containing cervical or ocular vestibular evoked myogenic potential in sudden hearing loss patients and information on associated vertigo and/or dizziness. Results: Sixteen of 62 initially selected articles met the inclusion criteria and were analyzed. Regarding the methodology of the evaluated studies, 8 studies were prospective, six were retrospective, one contained part of the data from a retrospective analysis and another part from a prospective analysis, and one study was cross-sectional. A total of 872 patients were evaluated (50.22% males and 49.77% females) with a mean age of 51.26 years. Four hundred and twenty-six patients (50.35%) had vertigo and/or dizziness associated with sudden hearing loss. The cervical vestibular evoked myogenic potential was performed in all studies, but only seven assessed the ocular vestibular evoked myogenic potential. The cervical vestibular evoked myogenic potential showed alterations in 38.65% of 846 evaluated ears, whereas ocular vestibular evoked myogenic potential showed alterations in 47.88% of 368 evaluated ears. The hearing recovery rate was analyzed by 8 articles, with 63.4% of 410 evaluated ears showing hearing recovery. Conclusions: The studies suggest that the assessment of the vestibular system using vestibular evoked myogenic potential seems to be important in the prognosis of sudden hearing loss. For better follow-up of patients with sudden hearing loss, the emphasis should not be limited to the cochlea, but also include the diagnosis and treatment of vestibular abnormalities, regardless of the presence of vertigo.

Resumo Introdução: A surdez súbita é uma emergência otorrinolaringológica que frequentemente cursa com graves danos à função auditiva e vestibular. O potencial evocado miogênico vestibular é um exame que permite a avaliação não invasiva da função do sistema otolítico e das vias vestíbulo-espinhal e vestíbulo-ocular. Objetivo: Avaliar a importância do potencial evocado miogênico vestibular na determinação do prognóstico dos pacientes com surdez súbita. Método: Uma busca de trabalhos publicados até dezembro de 2018 foi realizada nos bancos de dados PubMed, Cochrane, BVS e Lilacs com descritores cadastrados no MeSH. Foram incluídos artigos retrospectivos e prospectivos que contivessem o potencial evocado miogênico vestibular cervical ou ocular em pacientes com surdez súbita e informações sobre vertigem e/ou tontura associados. Resultados: Dezesseis de 62 artigos selecionados inicialmente preencheram os critérios de inclusão e foram analisados. Quanto à metodologia dos trabalhos avaliados, 8 estudos foram prospectivos, seis retrospectivos, um continha parte dos dados oriunda de uma análise retrospectiva e outra parte de uma análise prospectiva e um estudo foi transversal. Foram avaliados 872 pacientes (50,22% do gênero masculino e 49,77% feminino) com média de 51,26 anos. Do total de pacientes, 426 (50,35%) apresentavam vertigem e/ou tontura associada à surdez súbita. O potencial evocado miogênico vestibular cervical foi realizado em todos os estudos, porém o potencial evocado miogênico vestibular ocular em apenas sete. O potencial evocado miogênico vestibular cervical apresentou alteração em 38,65% de 846 orelhas avaliadas, enquanto o potencial evocado miogênico vestibular ocular estava alterado em 47,88% das 368 orelhas avaliadas. A taxa de recuperação auditiva foi analisada por 8 artigos, 63,4% de 410 orelhas avaliadas apresentavam recuperação auditiva. Conclusões: Os estudos demonstram que a avaliação do sistema vestibular com o uso do potencial evocado miogênico vestibular parece ter importância no prognóstico da surdez súbita. Para melhor acompanhamento do paciente com surdez súbita a ênfase não deve se restringir à cóclea, mas também no diagnóstico e tratamento de alterações vestibulares, independentemente da presença de vertigem.

Vestibular evoked myogenic potentials in the prognosis of sudden hearing loss ‒ a systematic review.

INTRODUCTION: Sudden hearing loss is an otorhinolaryngological emergency that often leads to severe damage to the auditory and vestibular function. The vestibular evoked myogenic potential is a test that allows a noninvasive evaluation of the otolithic system function and vestibulospinal and vestibulo-ocular pathways. OBJECTIVE: To evaluate the importance of vestibular evoked myogenic potential in determining the prognosis of patients with sudden hearing loss. METHODS: A search for articles published up to December 2018 was performed in the PubMed, Cochrane, VHL and LILACS databases using MeSH descriptors. Retrospective and prospective articles were included containing cervical or ocular vestibular evoked myogenic potential in sudden hearing loss patients and information on associated vertigo and/or dizziness. RESULTS: Sixteen of 62 initially selected articles met the inclusion criteria and were analyzed. Regarding the methodology of the evaluated studies, 8 studies were prospective, six were retrospective, one contained part of the data from a retrospective analysis and another part from a prospective analysis, and one study was cross-sectional. A total of 872 patients were evaluated (50.22% males and 49.77% females) with a mean age of 51.26 years. Four hundred and twenty-six patients (50.35%) had vertigo and/or dizziness associated with sudden hearing loss. The cervical vestibular evoked myogenic potential was performed in all studies, but only seven assessed the ocular vestibular evoked myogenic potential. The cervical vestibular evoked myogenic potential showed alterations in 38.65% of 846 evaluated ears, whereas ocular vestibular evoked myogenic potential showed alterations in 47.88% of 368 evaluated ears. The hearing recovery rate was analyzed by 8 articles, with 63.4% of 410 evaluated ears showing hearing recovery. CONCLUSIONS: The studies suggest that the assessment of the vestibular system using vestibular evoked myogenic potential seems to be important in the prognosis of sudden hearing loss. For better follow-up of patients with sudden hearing loss, the emphasis should not be limited to the cochlea, but also include the diagnosis and treatment of vestibular abnormalities, regardless of the presence of vertigo.

Optical Co-registration of MRI and On-scalp MEG.

To estimate the neural generators of magnetoencephalographic (MEG) signals, MEG data have to be co-registered with an anatomical image, typically an MR image. Optically-pumped magnetometers (OPMs) enable the construction of on-scalp MEG systems providing higher sensitivity and spatial resolution than conventional SQUID-based MEG systems. We present a co-registration method that can be applied to on-scalp MEG systems, regardless of the number of sensors. We apply a structured-light scanner to create a surface mesh of the subject's head and the sensor array, which we fit to the MR image. We quantified the reproducibility of the mesh and localised current dipoles with a phantom. Additionally, we measured somatosensory evoked fields (SEFs) to median nerve stimulation and compared the dipole positions between on-scalp and SQUID-based systems. The scanner reproduced the head surface with <1 mm error. Phantom dipoles were localised with 2.1 mm mean error. SEF dipoles corresponding to the P35m response for OPMs were well localised to the somatosensory cortex, while SQUID dipoles for two subjects were erroneously localised to the motor cortex. The developed co-registration method is inexpensive, fast and can easily be applied to on-scalp MEG. It is more convenient than traditional co-registration methods while also being more accurate.

Somatosensory and transcranial direct current stimulation effects on manual dexterity and motor cortex function: A metaplasticity study.

BACKGROUND: Non-invasive neuromodulation may provide treatment strategies for neurological deficits affecting movement, such as stroke. For example, weak electrical stimulation applied to the hand by wearing a "mesh glove" (MGS) can transiently increase primary motor cortex (M1) excitability. Conversely, transcranial direct current stimulation with the cathode over M1 (c-tDCS) can decrease corticomotor excitability. OBJECTIVE/HYPOTHESIS: We applied M1 c-tDCS as a priming adjuvant to MGS and hypothesised metaplastic effects would be apparent in improved motor performance and modulation of M1 inhibitory and facilitatory circuits. METHODS: Sixteen right-handed neurologically healthy individuals participated in a repeated measures cross-over study; nine minutes of sham- or c-tDCS followed by 30 min of suprasensory threshold MGS. Dexterity of the non-dominant (left) hand was assessed using the grooved pegboard task, and measures of corticomotor excitability, intracortical facilitation, short-latency afferent inhibition (SAI), short-interval intracortical inhibition (SICI), and SAI in the presence of SICI (SAIxSICI), were obtained at baseline, post-tDCS, and 0, 30 and 60 min post-MGS. RESULTS: There was a greater improvement in grooved pegboard completion times with c-tDCS primed MGS than sham + MGS. There was also more pronounced disinhibition of SAI. However, disinhibition of SAI in the presence of SICI was less and rest motor threshold higher compared to sham + MGS. CONCLUSIONS: The results indicate a metaplastic modulation of corticomotor excitability with c-tDCS primed MGS. Further studies are warranted to determine how various stimulation approaches can induce metaplastic effects on M1 neuronal circuits to boost functional gains obtained with motor practice.

Desempeño fonológico y actividad bioeléctrica auditiva en un niño con trastorno fonológico / Phonological performance and auditory bioelectric activity in a child with phonological disorder

Resumen Introducción. El trastorno fonológico es un déficit en la percepción, organización y producción fonológica del lenguaje. Los potenciales evocados auditivos de tronco cerebral identifican cambios electrofisiológicos generados en la vía auditiva, por tanto, el presente estudio pretende demostrar la utilidad de tales potenciales en la caracterización de los pacientes con trastornos fonológicos, permitiendo así evidenciar una alteración en la actividad bioeléctrica de la vía auditiva. Presentación del caso. Se presenta el caso de un menor con trastorno fonoaudiológico evaluado por medio de potenciales evocados auditivos de tronco cerebral, previa evaluación de la vía auditiva periférica excluyendo patologías adyacentes. El análisis de los resultados verifica que, en tiempo de transmisión del estímulo al recorrer la vía auditiva, se generó un aumento en las latencias absolutas de las ondas I, III y V, con aumento en las desviaciones estándar de la prueba. Conclusiones. Puede existir asociación entre el desarrollo fonológico y la actividad bioeléctrica de la vía auditiva, además, aumentando la muestra se podría generar una evaluación objetiva que valore algunas alteraciones del lenguaje en niños.

Abstract Introduction: Phonological disorder is a deficit in the perception, organization and phonological articulation of speech. Brainstem auditory evoked potentials identify electrophysiological changes generated in the auditory pathway. This study aims to demonstrate the usefulness of such potentials to characterize patients with phonological disorders and expose alterations in the bioelectric activity of the auditory pathway. Case presentation: This paper presents the case of a child with a phonological disorder evaluated using brainstem auditory evoked potentials, after evaluating the peripheral auditory pathway to rule out adjacent pathologies. The analysis of the results confirms that, during the transmission of the stimulus when crossing the auditory path, an increase was generated in the absolute latencies of waves I, III and V, with an increase an in the standard deviations of the test. Conclusions: An association between phonological development and bioelectric activity of the auditory pathway may exist. A larger sample could lead to an objective evaluation that assesses some language disorders in children.

Paired Associative Stimulation Delivered by Pairing Movement-Related Cortical Potentials With Peripheral Electrical Stimulation: An Investigation of the Duration of Neuromodulatory Effects.

BACKGROUND: Novel paired associative stimulation (novel-PAS), delivered by pairing movement-related cortical potentials (MRCPs) with electrical stimulation of somatosensory afferents, is an innovative neuromodulatory intervention. Novel-PAS results in increased corticomotor excitability and has potential as a rehabilitative adjunct to improve outcomes following stroke. The duration of its excitatory effect has important implications for how this novel PAS intervention might be applied within a traditional therapy session, but previous research has not explored its effects beyond 30 min post-intervention. OBJECTIVE: The objective was to explore changes in corticomotor excitability in healthy participants, over a 60-min period following a single session of novel-PAS. MATERIALS AND METHOD: Ten healthy adults completed a single session of novel-PAS, delivered by pairing 50 MRCPs with peripheral electrical stimulation. TMS was used to elicit motor evoked potentials (MEPs) of the tibialis anterior (TA) muscle, immediately prior to the intervention, and at 0, 30, 45, and 60 min post-intervention. RESULTS: When compared with pre-intervention, there was a statistically significant increase in the mean TA MEP amplitudes at 0 (p = 0.006), 30 (p = 0.006), 45 (p = 0.027), and 60 min post-intervention (p = 0.020). CONCLUSION: Corticomotor excitability is increased for 60 min following this novel-PAS intervention. Future research could investigate the optimal method of combining this neuromodulatory technique with traditional therapy.

Assessment Tools for Use in Patients with Ménière Disease: An Update.

A number of electrophysiological tests have been proposed for the initial diagnostic assessment or for the follow-up phase of patients affected by Ménière disease. The most common are: (i) vestibular evoked myogenic potentials (VEMPs); (ii) electrocochleography (ECochG); and (iii) otoacoustic emissions (OAEs). This paper presents the latest clinical developments with these 3 testing modalities. The PubMed, Embase, and Cinahl databases were searched from 2006 to December 2016. Full-text articles were obtained in cases where the title, abstract, or key words suggested that the study may be eligible for this review. The medical subject heading (MeSH) terms included the following: Ménière, hearing threshold, vestibule, otoacoustic emissions, inner ear, ECochG, VEMPs. There were 368 identified papers, out of which 87 were eligible for inclusion. Overall the data in the literature are still limited and the recommended procedures have not reached an international consensus. From the available data, one can conclude that none of the electrophysiological tests could be considered as pathognomonic, for the diagnosis of Ménière disease: presently, the tests could be mostly used in a supportive role to the clinical diagnosis. Hopefully, in the future, improved technology in electrophysiological testing could contribute to the development of better strategies for the diagnosis of Ménière disease.

Influence of vertebral column distraction on spinal cord volume: an experimental study in a goat model.

INTRODUCTION: Spinal cord injury may be related to excessive distraction of the spinal cord during surgical correction of spinal deformities by vertebral column resection. This study aimed to investigate how vertebral column distraction influences spinal cord volume to establish the safe range in a goat model. MATERIALS AND METHODS: A vertebral column resection was performed on the tenth thoracic vertebra of 11 goats. The spinal cord was distracted until the somatosensory evoked potential signals were decreased to 50 % from baseline amplitude or were delayed by 10 % of the baseline peak latency. The osteotomy segment was stabilized with a PEEK mesh cage filled with bone graft, and the pedicle screws on the rods were then tightened in this position. Spinal cord volume was calculated using Mimics software, and T10 height, disk height, osteotomy segment height, and spinal segment height were measured using the MRI image workstation. RESULTS: Three goats were excluded, and data obtained from the eight remaining goats were analyzed. The safe limit of distraction distance was 11.8 ± 3.65 mm, and the distraction distance was strongly correlated with the difference between the pre- and postoperative measurements (d value) of spinal cord volume per 1 mm of osteotomy segment height (r = -0.952, p < 0.001), but was not correlated with T10 body height (r = 0.16, p = 0.71), spinal segment height (r = 0.29, p = 0.49), disk height (r = -0.12, p = 0.98), or the d value (pre-post) of spinal cord volume per 1 mm of spinal segment height (r = 0.45, p = 0.26). The mean d value (pre-post) of spinal cord volume per 1 mm of osteotomy segment height was 10.05 ± 0.02 mm(3) (range 10.02-10.08 mm(3)). CONCLUSION: The maximum change in spinal cord volume per 1-mm change in height was in the osteotomy segment, and its safe limit was 10.05 ± 0.02 mm(3). The safe limit of spinal cord distraction can be calculated using the spinal cord volume per unit 1-mm change in height.