Based on contemporary theoretical knowledge in this prospective study we outline the relationship between a chosen surgical approach (anterior or posterior approach) as it relates to the localization of spinal cord lesion (anterior or posterior spinal pathways) assessed by the use of evoked potentials (SEP, MEP) and the effect of this approach on the postoperative state of patients with cervical spondylotic myelopathy. Furthermore we evaluate clinical outcome of these patients according to several aspects of their MRI and X-ray findings. The study, from 2006 to 2010, comprised 65 patients with clinical signs of cervical myelopathy. These patients had been indicated for surgery, which subsequently was performed by using either the front (anterior - a) or back (posterior - p) approach. The patients were assessed using Nurick and mJOA scores before surgery, then at 12 months, and finally 24 months after surgery. In addition, they were preoperatively examined with a battery of evoked potentials (EP) - somatosensory evoked potential (SEP) and motor evoked potential (MEP) tests. Based on EP, principal spinal cord disability was determined: A - anterior (maximum changes in MEP), P - posterior - maximum change in SEP). The entire group was, on the basis of EP partitioning and the surgical approach used, divided...

Made available in DSpace on 2014-08-26T17:31:43Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 69589.pdf: 12544721 bytes, checksum: e242b76c9cdf8b6c04d9e749f41a5d1f (MD5) / Fundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Programa de Pós-Graduação em Saúde da Criança e da Mulher. Rio de Janeiro, RJ, Brasil. / As mucopolisacaridoses (MPS) são doenças geneticamente determinadas, causadas pela deficiência de enzimas lisossômicas, o que leva ao acúmulo de glicosaminoglicanos (GAGs) universalmente. As mielopatias cervicais ao nível da junção craniocervical são uma complicação frequente, grave e multifatorial das MPS. Este trabalho teve como principal objetivo o estudo das vias sensitivas e motoras centrais (cordão posterior e trato córtico-espinhal) em topografia medular cervical nos pacientes com mucopolissacaridoses (MPS), utilizando os potenciais evocados somatossensitivos e motores. Como objetivos específicos, a avaliação dos pacientes com MPS em fases distintas da doença, a demonstração da existência de comprometimento da condução nervosa nos trajetos das vias medulares na topografia já mencionada e o destaque do papel dos testes neurofisiológicos (funcionais) no diagnóstico, acompanhamento e na tomada de decisões terapêuticas nos pacientes com MPS. Foi realizado um estudo transversal, de uma série de casos, tendo como metodologia a revisão de prontuários, no Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira. Foram incluídos os pacientes com o diagnóstico de MPS, sem restrições quanto à idade, aos subtipos da doença ou ao fato de estarem ou não sob tratamento específico e excluídos aqueles pacientes com lesões graves do sistema nervoso central que impedissem a realização dos testes propostos. Os dados colhidos referiram-se à idade dos pacientes, o tipo de MPS, os achados do exame neurológico, os resultados dos estudos de imagem (ressonância magnética) da coluna cervical e os parâmetros neurofisiológicos encontrados nos potenciais evocados somatossensitivos (PESS) e motores (PEM), que incluiram as latências das ondas (N9, N13 e N20 nos PESS de membros superiores e N21 e P37 nos PESS de membros inferiores), os tempos de condução central (N20 – N13 e P37 – N21) e o tempo de condução motora central (nos PEM de membros superiores e inferiores). Foram analisados resultados de cinquenta e oito exames de potenciais evocados somatossensitivos e motores, realizados em vinte e oito pacientes com MPS. Todos os exames foram anormais, com alterações mais graves nos exames de PEM. / Mucopolysaccharidosis (MPS) are inherited metabolic diseases caused by deficiency of lysosomal enzymes leading to progressive accumulation of glycosaminoglycans (GAGs) in nearly all cell types, tissues and organs. Cervical myelopathy at the cranio-cervical junction is a frequent, severe and multifactorial complication of MPS. The first objective of the present study is the evaluation os the function of central neural pathways (brain stem and spinal cord posterior columns and corticospinal tract in patients with MPS using somatosensory evoked potentials (SEP) and motor evoked potentials (MEP). The secondary objectives are the evaluation of the patients in different periods of disease, the diagnostic of the lesions in cervical spinal cord and the remark of the role of these neurophysiological tests in diagnostic, follow-up and therapeutic decisions. This cross-sectional study included all patients with MPS of Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, despite age, type of disease, enzyme replacement therapy or not, except the patients with severe central nervous system lesions in whom the neurophysiological evaluation became impossible. Data included the age of patients, type of disease, the findings in neurological examination, magnetic resonance imaging of cervical spinal cord and the neurophysiological parameters [the latencies of N9, N13 and N20 waveforms, central conduction time (upper limbs SEP), the latencies of N21 and P37 waveforms, central conduction time (lower limbs SEP), central motor conduction time (upper and lower limbs MEP)].Twenty-eight patients were enrolled and fifty-eigth tests (SEP and MEP, upper and lower limbs) were performed in these patients. All tests were abnormal with most severe functional impairment in MEP tests.

A estimulação magnética transcraniana (EMT) aplicada com diferentes orientações da bobina causa variações na amplitude e na latência dos potenciais evocados motores (PEM) dos músculos da mão. No entanto, as propriedades dos PEM são afetadas também pelos sistemas de detecção, e.g. localização e tamanho dos eletrodos de aquisição, e pela anatomia do músculo analisado, e.g. arquitetura dos tecidos muscular e adiposo. Neste estudo, verificamos como variam a distribuição espacial, a amplitude pico a pico, a latência, a velocidade de condução da fibra muscular e a frequência mediana do espectro de potência dos PEM em função da orientação da bobina de EMT. Utilizamos uma matriz bidimensional de eletrodos de superfície (grade com 13 linhas e 5 colunas) para aquisição do sinal de eletromiografia de superfície (EMGs) do músculo abdutor curto do polegar (ACP) em oito orientações da bobina de EMT em relação à linha sagital, que conecta o ínio ao násio. Duas abordagens distintas foram adotadas para comparação da amplitude em função da orientação da bobina: na primeira abordagem, calculamos a amplitude pico a pico média dos PEM compreendidos em uma região ativa do músculo localizada espacialmente a partir da matriz de EMGs, na segunda abordagem extraímos a amplitude do PEM no sinal diferencial de dois grupos de eletrodos simulando um sistema de EMGs em configuração bipolar, comumente utilizado nos procedimentos em EMT. Em ambos os métodos, identificamos amplitudes máximas para orientações da bobina em ângulos de 45° e 90°, corroborando os achados da literatura. A latência, frequência mediana e velocidade de condução dos PEM não apresentaram variações significativas com a orientação da bobina. Os mapas de distribuição espacial dos PEM indicam uma atividade muscular localizada na porção distal do músculo ACP para todos os ângulos de aplicação da EMT, demonstrando que os eletrodos convencionais de EMGs podem não estar idealmente localizados sobre a região do músculo ativada pela EMT. Por fim, identificamos que um sistema de neuronavegação pode facilitar a localização da estrutura cerebral a ser estimulada e aumentar a precisão no posicionamento da bobina. Adicionamos uma ferramenta para cálculo da orientação da bobina em função da linha sagital média de cada sujeito ao neuronavegador InVesalius Navigator, a ser utilizado nos próximos experimentos. / Transcranial magnetic stimulation (TMS) pulses with different coil orientations causes changes in amplitudes and latencies of motor evoked potentials (MEP) in muscles of the hand. Nonetheless, the properties of MEP are also affected by the systems of detection, e.g. placement and size of acquisition electrodes; and by the target muscle anatomy, e.g. architecture of fat and muscles tissues. In this study, we assessed the effect of TMS coil orientation on MEP spatial distribution, peak-to-peak amplitude, latency, conduction velocity of muscle fiber and median frequency, from the abductor pollicis brevis (APB) muscle. A grid of electrodes (13 lines and 5 columns) was used to detect the surface electromyography (sEMG) signals from the APB at eight different TMS coil orientations in respect to the midsagital line, connecting the inium and nasium. Two distinct approaches were adopted to compare the amplitude according to the coil orientation: first, we calculated the mean amplitude of MEP in the electrodes of the matrix over an active region of the muscle. Second, we extracted the amplitude of MEP in a single differential signal from two groups of matrix electrodes simulating a conventional sEMG bipolar configuration, commonly used in TMS experiments. In both cases, the maximum MEP amplitudes were induced at coil orientations of 45° and 90°, confirming the past findings in literature. However, we could not identify significant differences in latency, median frequency and conduction velocity of MEP according to different stimulus orientation. Maps of spatial distribution showed a localized muscle activity at the distal portion of the APB muscle for all the coil orientations, indicating that conventional bipolar sEMG electrodes may not be rightly placed over the active portion of the muscle recruited by TMS. Finally, we considered that a neuronavigation system could facilitate the localization of brain internal structures to apply TMS stimulus and improve the accuracy of coil handling and positioning over the stimulation point. Thereafter, we developed a computational tool to the InVesalius Navigator, to track the TMS coil position and orientation in respect to the subjects midsagital line to be used in future experiments.

Nas cirurgias de ressecção de tumores do ângulo pontocerebelar, a preservação do nervo facial está entre os seus principais objetivos. Diversas técnicas neurofisiológicas vêm sendo empregadas com o objetivo de predizer déficit imediato do nervo facial no pós-operatório, como a eletromiografia contínua para registro de atividade neurotônica tipo A, a estimulação direta do nervo facial no sítio tumoral e a estimulação elétrica transcraniana com captação em músculos de face. Analisamos 23 pacientes de forma prospectiva, submetidos à cranectomia retrossigmoide para ressecção de tumores em fossa posterior no período de janeiro de 2008 a março de 2010. Os pacientes foram avaliados clinicamente de acordo com a gradação de House-Brackmann para a função do nervo facial. Foram observadas a ocorrência de atividade neurotônica do tipo A, também chamada de atividade irritativa, a queda da amplitude do potencial motor do nervo facial obtido com a estimulação elétrica transcraniana e o aumento na intensidade do estímulo elétrico da estimulação elétrica transcraniana para a obtenção desse potencial. Esses dados foram relacionados à condição clínica do nervo facial no pós-operatório imediato e na última data de acompanhamento. Observamos que a queda da amplitude do nervo facial acima de 60% do seu valor inicial basal foi a variável mais sensível (89%) e com maior valor preditivo positivo (92%) para a piora clínica do nervo facial. A ocorrência de atividade irritativa isolada foi a variável menos sensível (7%) e com valor preditivo positivo de apenas 25%. O aumento na intensidade da estimulação elétrica transcraniana não mostrou significância estatística (p = 0,287). Concluímos que das variáveis estudadas, a queda na amplitude do potencial evocado motor do 7º nervo craniano acima de 60% foi a melhor na predição de piora clínica imediata do nervo facial / The preservation of facial nerve function is one of the most important goals of the cerebellopontine angle tumor resection surgeries. Valuable neurophysiologic techniques have been used to predict the facial nerve outcome, such as continuous electromyography to identify neurotonic activity type A, direct facial nerve stimulation in the vicinity of the tumor and transcranial motor evoked potential recording in face muscles. We analyzed 23 patients undergoing retrossigmoidectomy approaches for posterior fossa tumor resection between January 2008 and March 2010. Their facial nerve function was evaluated using the House-Brackmann score. We correlated the occurrence of type A neurotonic activity, facial nerve motor evoked potential amplitude obtained with transcranial electrical stimulation and increase in the electric stimulus threshold to the immediate and last follow-up facial nerve outcome. In this series, the increase in electric stimulus threshold showed no statistical significance (p = 0,287). The drop of the facial nerve motor evoked potential amplitude equal or above 60% was the most sensitive (89%) and with the highest positive predictive value (92%) in identifying poor facial nerve outcome. The occurrence of neurotonic activity type A showed to be the least sensitive (7%) and with the poorest positive predictive value (25%) of them. We conclude that among the used parameters, the drop of the final 7º nerve motor evoked potential amplitude equal or above 60% of basal recording was the best one in predicting poor facial nerve outcome

Abstract In the Nordic countries, event-free survival (EFS) exceeds 80% in certain groups of children treated for acute lymphoblastic leukaemia (ALL). With the improved cure rates, however, there are more children suffering from neurological late effects, especially due to therapy directed at the central nervous system (CNS). The aim of this study is to examine the changes taking place in the nervous system after leukemia treatment and to evaluate the role of treatment in these changes in patients and in an animal model. Twenty-seven ALL survivors and healthy controls were examined by means of motor evoked potentials (MEPs). ALL survivors were also examined clinically. The children with ALL continued to show decreased motor nerve conduction in the peripheral nerves, but not within the CNS, five years after the cessation of treatment. Clinical neurological findings were obtained in 33% of the cases. The MEP results indicated reversibility of the motor injury due to CNS effects. Nineteen patients underwent perfusion magnetic resonance imaging (MRI) at the cessation of treatment or 4-8 years after the treatment. Seventeen of them also underwent single-photon emission computed tomography (SPECT). The studies showed small perfusion defects in SPECT, which were not visible by perfusion MRI. Methotrexate (Mtx) neurotoxicity was studied in a swine model using functional MRI, brain perfusion SPECT, iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl) tropane ([123I]β-CIT) SPECT and whole-hemisphere autoradiography with [125I]β-CIT in ten Mtx-treated animals and five control animals. Mtx-related changes in the brain could be detected as reduced or negative blood-oxygen-level-dependent (BOLD) responses to somatosensory activation in BOLD contrast MRI, which indicates changes in flow metabolism coupling. Perfusion defects in brain SPECT were seen in the Mtx group and the control group, which suggests that the perfusion defects seen in brain SPECT are probably multifactorial. The change in dopamine transporter (DAT) density in the Mtx group was not different from that in the controls. The abnormalities in nerve conduction after treatment in survivors of ALL were partly reversible years after the treatment. The patients had perfusion defects in SPECT imaging which were not seen in perfusion MRI. The clinical significance of these defects remains obscure. The animal model suggested perfusion defects to be multifactorial.

Based on contemporary theoretical knowledge in this prospective study we outline the relationship between a chosen surgical approach (anterior or posterior approach) as it relates to the localization of spinal cord lesion (anterior or posterior spinal pathways) assessed by the use of evoked potentials (SEP, MEP) and the effect of this approach on the postoperative state of patients with cervical spondylotic myelopathy. Furthermore we evaluate clinical outcome of these patients according to several aspects of their MRI and X-ray findings. The study, from 2006 to 2010, comprised 65 patients with clinical signs of cervical myelopathy. These patients had been indicated for surgery, which subsequently was performed by using either the front (anterior - a) or back (posterior - p) approach. The patients were assessed using Nurick and mJOA scores before surgery, then at 12 months, and finally 24 months after surgery. In addition, they were preoperatively examined with a battery of evoked potentials (EP) - somatosensory evoked potential (SEP) and motor evoked potential (MEP) tests. Based on EP, principal spinal cord disability was determined: A - anterior (maximum changes in MEP), P - posterior - maximum change in SEP). The entire group was, on the basis of EP partitioning and the surgical approach used, divided...

La sclérose en plaques est la maladie non tumorale du système nerveux la plus fréquente du sujet jeune. Elle est définie comme une atteinte démyélinisante inflammatoire multifocale et chronique de la substance blanche du système nerveux central d’origine dysimmunitaire. Le handicap moteur est l’un des risques évolutifs principaux de cette maladie. Mieux caractériser les mécanismes du dysfonctionnement du système moteur (atteinte de la voie motrice centrale efférente, altération du réseau moteur cortical à l’origine du mouvement) de même que les mécanismes compensatoires qui le limitent est un enjeu important dans la compréhension et la prévention de l’apparition du handicap. L’étude de ces mécanismes au stade précoce de la maladie permet de mieux comprendre les liens entre l’atteinte tissulaire, les mécanismes de compensation et les conséquences fonctionnelles. Nos travaux ont permis au stade précoce de la SEP de mieux caractériser l’atteinte fonctionnelle de la voie motrice centrale, de montrer l’influence de l’atteinte encéphalique diffuse sur la réorganisation corticale du système moteur et enfin de démontrer l’existence d’une plasticité cérébrale fonctionnelle basale du réseau moteur non dominant corrélée avec les changements d’activation observés lors du mouvement au sein du même réseau. / Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder of the central nervous system which is frequently responsible for motor disability. Better assessment of pathophysiological process implicated in motor system dysfunction (cortico-spinal tract or more diffuse tissue damage) as well as the compensatory mechanises are critical in the understanding and the prevention of disability. Their study in the early stage of the disease will allow to a better understanding of the links between tissue injury, compensatory mechanisms and functional consequences. We have better characterized functional dysfunction of the central motor pathway at the early stage of multiple sclerosis. We have also evidenced the influence of diffuse brain injury on functional motor cortical reorganization. Last, we have demonstrated the existence of a basal functional plasticity at rest of the nondominant motor network that is correlated with its functional plasticity during action.

Neuronavigation and transcranial magnetic stimulation (TMS) are valuable tools in clinical and research environment. Neuronavigation provides visual guidance of a given instrument during procedures of neurological interventions, relative to anatomic images. In turn, TMS allows the non-invasive study of cortical brain function and to treat several neurological disorders. Despite the well-accepted importance of both techniques, high-cost of neuronavigation systems and limited spatial accuracy of TMS in targeting brain structures, limit their applications. Therefore, the aim of this thesis was to i) develop an open-source, free neuronavigation software, ii) study a possible combination of neuronavigation and 3D printing for surgical planning, and iii) construct a multi-channel TMS coil with electronic control of electric field (E-field) orientation. In the first part, we developed and characterized a neuronavigation software compatible with multiple spatial tracking devices, the InVesalius Navigator. The created co-registration algorithm enabled tracking position and orientation of instruments with an intuitive graphical interface. Measured accuracy was similar to that of commercial systems. In the second part, we created 3D printed models from patients with neurological disorders and assessed the errors of localizing anatomical landmarks during neuronavigation. Localization errors were below 3 mm, considered acceptable for clinical applications. Finally, in the last part, we combined a set of two thin, overlapping coils to allow electronic control of the E-field orientation and investigated how the motor evoked responses depend on the stimulus orientation. The developed coil enabled the stimulation of the motor cortex with high angular resolution. Motor responses showed the highest amplitude and lowest latency with E-field approximately perpendicular to the central sulcus. In summary, this thesis provides new methods to improve spatial accuracy of techniques to brain interventions. / A neuronavegação e a estimulação magnética transcraniana (EMT ou TMS, do termo em inglês transcranial magnetic stimulation) têm sido apresentadas como ferramentas valiosas em aplicações clínicas e de pesquisa. A neuronavegação possibilita a localização de instrumentos em relação a imagens anatômicas durante procedimentos de intervenção neurológica. Por sua vez, a EMT permite o estudo não invasivo da função cerebral e o tratamento de doenças neurológicas. Apesar da importância de ambas as técnicas, o alto custo dos sistemas de neuronavegação e a reduzida precisão espacial da EMT em ativar estruturas cerebrais limitam suas aplicações. Sendo assim, o objetivo desta tese foi: i) desenvolver um software de neuronavegação gratuito e de código aberto, ii) estudar a combinação entre neuronavegação e impressão 3D para planejamento cirúrgico, e iii) construir uma bobina de EMT multicanal com controle eletrônico da orientação do campo elétrico (CE). Na primeira parte, desenvolvemos e caracterizamos um software de neuronavegação compatível com vários rastreadores espaciais, o InVesalius Navigator. O algoritmo criado possibilitou o rastreamento de instrumentos por uma interface gráfica intuitiva. A precisão medida foi semelhante à de sistemas comerciais. Na segunda parte, imprimimos modelos 3D de pacientes com patologias neurológicas e avaliamos os erros de localização de marcos anatômicos durante a neuronavegação. Os erros de localização foram inferiores a 3 mm, considerados aceitáveis para aplicações clínicas. Por fim, na última parte, combinamos duas bobinas sobrepostas para controlar eletronicamente a orientação do CE, e investigamos como as respostas motoras evocadas dependem da orientação da corrente. A bobina desenvolvida possibilitou estimular o córtex motor com alta resolução angular. As respostas motoras apresentaram maior amplitude e menor latência para orientação do CE aproximadamente perpendicular ao sulco central. Em suma, esta tese fornece novos métodos para melhorar a precisão espacial de técnicas de intervenção com o cérebro.

Vestibular evoked myogenic potentials (VEMPs) are short-latency electromyograms evoked by high-level acoustic stimuli recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle. These responses are presumed to originate in the saccule. The purpose of this preliminary report is to provide an overview of our initial experience with the VEMP by describing the responses obtained in five subjects. Click-evoked VEMPs were present at short latencies in two normal-hearing subjects, one patient with profound congenital sensorineural hearing loss, and one patient with a severe sensorineural hearing loss due to Meniere's disease. Additionally, VEMPs were absent in a patient with profound sensorineural hearing loss following removal of a cerebellopontine angle tumor. The amplitude of the VEMP was influenced by the amount of background activity of the SCM muscle, stimulus level, and stimulus frequency. Tone-burst evoked responses showed an inverse relationship between stimulus frequency and response latency. VEMPs may prove to be a reliable technique in the clinical assessment of vestibular function.

No description available.