Evoked potential by median nerve stimulation (SSEP): subcortical components

A review of the literature is done regarding designation, potential fields and implicated generators for subcortical components of the short latency median nerve somatosensory evoked potentials.Este estudo constitui uma revisão de literatura realizada com a finalidade de se relacionar a designação, as características dos campos de potencial e os geradores implicados, para os componentes subcorticais do potencial evocado somatossensorial por estimulação do nervo mediano no punho.Escola Paulista de Medicina Serviço de Neurofisiologia ClínicaUNIFESP, EPM, Serviço de Neurofisiologia ClínicaSciEL

Uma breve nota histórica sobre a classificação das fibras nervosas

This is a brief review of the literature focused on the articles that formed the basis for the classification of the nerve fibers. Mention is also made to the origin of the nomenclature of the different motoneurons (a, b and g).Os autores fazem uma breve revisão da literatura com foco nos artigos que deram origem à classificação das fibras nervosas. É também mencionada no texto a origem da nomenclatura dos diferentes neurônios motores (a, b and g).Federal University of São Paulo Section on Research and Pos-graduation in Clinical NeurophysiologyUNIFESP, Section on Research and Pos-graduation in Clinical NeurophysiologySciEL

Comparação por análise visual entre as espículas promediadas e as espículas individuais nas descargas epileptiformes rolândicas

PURPOSE:This study compared some morphological features of individual rolandic epileptiform discharges, used to obtain an averaged estimate, with those of the resulting estimate. METHOD: Twenty-four averaged discharges from EEGs of 24 children showing rolandic spikes were compared with 480 individual discharges used in the averaging. The analysis was based on the occurrence of tangential dipole and double spike patterns. RESULTS: In 15 averaged discharges the tangential dipole pattern was found. Individual spikes used in the averaging process displayed the same pattern in 35-100% of them; in the remaining 9 averaged discharges, up to 20% of the individual spikes showed the same pattern, although this was not found in the averaged waveforms. Double spike pattern was found in 11 of the averaged waveforms and was recognized in 50-100% of its individual discharges, whereas up to 45% of individual spikes showed this pattern without expression in the averaged waveform. CONCLUSION: When visually analyzing an EEG with rolandic spikes, caution should be exercised in characterizing these patterns, since a few discharges showing them may not be expressed in the averaged waveform and the clinical correlations proposed for these patterns may not apply.OBJETIVO: Comparar as características morfológicas das descargas epileptiformes rolândicas individuais usadas para se obter uma descarga promediada com a resultante promediada. MÉTODO: Vinte e quatro descargas promediadas dos EEG de 24 crianças com descargas epileptiformes rolândicas foram comparadas com as 480 descargas individuais utilizadas na promediação. A análise foi baseada na ocorrência de dipolo tangencial e dupla espícula. RESULTADOS: Em 15 descargas promediadas o dipolo tangencial estava presente. As espículas individuais usadas na promediação mostraram o mesmo padrão em 35-100% das descargas. Nas 9 descargas promediadas restantes, até 20% das descargas individuais apresentavam o padrão, embora este não estivesse presente na resultante promediada. O padrão dupla espícula foi encontrado em 11 descargas promediadas, tendo sido reconhecido em 50-100% das descargas individuais, enquanto até 45% das espículas individuais mostraram este padrão sem que este estivesse presente na resultante promediada. CONCLUSÃO: Quando se procede à analise visual de um EEG com descargas epileptiformes rolândicas é necessário cuidado na caracterização desses padrões, pois algumas descargas podem apresentá-los sem manter a sua expressão na resultante promediada e as correlações clínicas referentes a esse padrões podem não se aplicar.UNIFESP-EPM Neurology and Neurosurgery DepartmentUNIFESP, EPM, Neurology and Neurosurgery DepartmentSciEL

Paresthesia and/or pain affecting the hand and/or wrist as a referral for electrodiagnostic studies

To study the reasons for referral to electrodiagnostic evaluation, 490 patients referred for electrodiagnostic evaluation to two laboratories (UNIFESP and UNEF) answered the following question: What was the reason that brought you to look for a physician and that led him to ask this examination? Paresthesia and/or pain were answered as the main reason by 175 of them (26% UNIFESP and 40% UNEF). The electromyographical examinations were normal in 30.8% and 35.3% and involvement of the median nerve at the wrist was detected in 5 9% and 51.5% of them. Nocturnal symptoms and paresthesia were commonly noted in both groups of patients; they, however, were not able to separate the patients with and without median nerve compression at the wrist. The question asked seems to be a useful selection instrument, to select two similar symptomatic samples of patients from two laboratories serving with very different target populations.Com o objetivo de conhecermos os motivos de encaminhamento para estudo eletrofisiológico, perguntamos a 490 pacientes, encaminhados a dois laboratórios de neurofisiologia (UNIFESP e UNEF): Qual o motivo que a(o) levou a procurar o médico e que fez com que ele solicitasse este exame? Parestesia e/ou dor nas mãos e/ou punhos foram espontaneamente referidas como motivo principal por 175 deles (26% UNIFESP e 40% UNEF). O exame eletroneuromiográfico foi normal em, respectivamente, 30,8% e 35,3% e revelou compressão do nervo mediano no carpo em 59% e 51,5% destes pacientes. Sintomas noturnos e parestesia foram comuns nos dois grupos de pacientes, mas não foram capazes de discriminar aqueles com e sem compressão do nervo mediano no carpo. O sintoma dor predominou nos pacientes com exame normal. A pergunta formulada pareceu ser bom instrumento de seleção. Conseguiu selecionar duas amostras de pacientes sintomáticos semelhantes, em laboratórios com população alvo muito diferente.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Setor de Neurofisiologia ClínicaUNIFESP, EPM, Setor de Neurofisiologia ClínicaSciEL

Pudendal nerve latency time in normal women via intravaginal stimulation

INTRODUCTION & OBJECTIVES: Studies of motor conduction for the efferent functional assessment of the pudendal nerve in women with pelvic dysfunctions have been conducted through researching distal motor latency times. The transrectal approach has been the classic approach for this electrophysiological examination. The objective of the present study is to verify the viability of the transvaginal approach in performing the exam, to establish normal values for this method and to analyze the influence of age, stature and parity in the latency value of normal women. MATERIALS AND METHODS: A total of 23 volunteers without genitourinary pathologies participated in this study. In each, pudendal motor latency was investigated through the transvaginal approach, which was chosen due to patient s higher tolerance levels. RESULTS: The motor response represented by registering the M-wave was obtained in all volunteers on the right side (100%) and in 13 volunteers on the left side (56.5%). The mean motor latency obtained in the right and left was respectively: 1.99 ± 0.41 and 1.92 ± 0.48 milliseconds (ms). There was no difference between the sides (p = 0.66). Latency did not correlate with age, stature or obstetric history. The results obtained in the present study were in agreement with those found by other researchers using the transrectal approach. CONCLUSION: The vaginal approach represents an alternative for pudendal nerve distal motor latency time, with similar results to those achieved through the transrectal approach. Normative values obtained herein might serve as a comparative basis for subsequent physiopathological studies.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departments of Urology and NeurologyUNIFESP, EPM, Departments of Urology and NeurologySciEL

Pudendo-anal reflex in normal women

The pudendo-anal reflex was studied in a sample of 31 normal women. Responses were obtained after bilateral independent stimulation of the clitoris, with surface recordings from both sides of the external anal sphincter. Reponses were elicited with double-pulses of 0,2 ms duration with a interstimulus interval of 5 ms, frequency of stimulation was lower than 0,5 Hz. A minimal of four responses were recorded after supramaximal stimulation. In one volunteer no response was recorded after unilateral stimulation. Latencies of the responses from the right and left sides of the anal sfincter after right and left stimulation were 36.35±6.37, 36.28±6.23, 35.88±4.68, 36.44±4.45ms, respectively. No relation was detected between latencies and age, body mass index and parity (considering either total parity or vaginal delivery only). In 12% of the recordings uncertainty was introduced in the latency measurements related to a poor signal-noise ratio.São descritas observações do registro do reflexo pudendo-anal em mulheres sem queixas de incontinência urinária. Foram estudadas 31 voluntárias adultas, com estimulação elétrica bilateral e independente do clitóris e registros de superfície em ambos os lados do músculo esfíncter externo do ânus (EEA). As respostas foram obtidas com pulsos duplos de 0,2 ms de duração e intervalos de 5 ms, aplicados a uma freqüência menor que 0,5 Hz. Foram medidas as latências iniciais das respostas. Não foram evidenciadas diferenças entre as respostas obtidas de cada lado do EEA e nem entre os lados, com relação aos estímulos. Uma das voluntárias não apresentou respostas após estimulação de um dos lados. Não foram observadas diferenças relacionadas a paridade total e nem com a presença de partos vaginais. A idade e o índice de massa corpórea não se correlacionaram com as respostas. Em 12% das respostas, a medida das latências foi dificultada pela baixa relação sinal-ruído.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

Translation and validation of an instrument for evaluation of severity of symptoms and the functional status in carpal tunnel syndrome

The objective of the present study was to translate, to do cultural equivalence and validation of the Levine et al. (1993) or Boston Carpal Tunnel Questionnaire (BCTQ) to Portuguese. The BCTQ application to patients, selected by the question What was the reason that brought you to look for a physician and that led him to ask this examination? showed very good reproducibility. The validity was measured through the comparison of the severity symptoms scores (SSS) and the functional status scores (FSS) with the results of grip forces, Minnesota, two point discrimination, Semmes-Weinstein filaments perception and sensory conduction at the median nerve. The internal consistency was evaluated through Chronbach's alpha coefficient comparing the SSS and the FSS. The measuring properties were evaluated through paired t-test between pre and pos-surgical scores. Reproducibility, internal consistency, validation and measuring properties of the translated BCTQ were similar to those found by Levine et al. with the original version.Este estudo tem por objetivo traduzir, fazer a equivalência cultural e validar o questionário de Levine et al. (1993) ou Boston Carpal Tunnel Questionnaire (BCTQ), para o português. O BCTQ aplicado a pacientes selecionados pela pergunta Qual o motivo que a(o) levou a procurar o médico e que fez com que ele solicitasse este exame? mostrou boa reprodutibilidade. A validade foi medida comparando o escore de gravidade dos sintomas (EGS) e o escore do estado funcional (EEF) aos resultados dos testes de força de preensão e pinça, Minnesota, discriminação entre dois pontos, Semmes-Weinstein e velocidade de condução sensitiva no nervo mediano. A consistência interna foi avaliada pelo coeficiente a de Chronbach, comparando o EGS ao EEF. A propriedade de medida foi avaliada pelo teste t pareado, comparando escores pré-cirúrgicos aos pós-cirúrgicos. Reprodutibilidade, consistência interna, validade e propriedades de medida do BCTQ traduzido foram semelhantes às encontradas por Levine et al. na versão original.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

Determination of electric current perception threshold in a sample of normal volunteers

Reference values using the instrument Neurometer® were determined and compared with those suggested by the manufacturer; the sensory thresholds for the different frequencies in different body segments were determined; the influence of age, level of education, gender and the reutilization of the electrodes in the different sites were also evaluated. Sensory threshold was determined in 101 normal volunteers (68 women), ages ranged from 17 to 87 years old. The procedure was fully automated with the sensory threshold being determined by the method of limits followed by the forced choice method. Analysis of the results revealed that: there was a significant difference between the values obtained for the index fingers and the halux; no difference was detected between both index fingers; gender and level of instruction had no effect on the results, age had a small influence after stimulation with 2000Hz and 250Hz; three reutilizations of the electrodes did not affect the results on the index fingers, however at the halux, the third utilization deteriorated the results from the 2000Hz stimulation. Except for the 2000Hz stimulation, significant differences were suggested between the values reported here and those provided by the manufacturer.Determinaram valores de referência para limiares de percepção de corrente elétrica senoidal em indivíduos normais, utilizando-se o instrumento Neurometer®; contrastaram-se os resultados com os fornecidos pelo fabricante; analisaram-se os limiares em diferentes segmentos corporais e avaliou-se o efeito da idade, sexo, grau de escolaridade e reutilização dos eletrodos. Estudou-se uma amostra de 101 voluntários normais (68 mulheres), com idades entre 17 e 87 anos. O procedimento foi completamente automatizado utilizando o método de límites e o de escolha forçada. Houve diferença significante entre os limiares obtidos no dedo indicador e no hálux nas três freqüências. Não houve diferenças significantes em relação ao sexo e grau de escolaridade; a idade apresentou discreta relação em algumas medidas. A reutilização dos eletrodos por três vezes nos dedos indicadores não comprometeu a confiabilidade, porém no hálux direito a reutilização por mais de duas vezes comprometeu a determinação do limiar para 2000Hz. Os valores obtidos diferiram das referências fornecidas pelo fabricante, nas freqüências 250Hz e 5Hz.Universidade Federal de São Paulo (UNIFESP) Setor de Neurofisiologia ClínicaUNIFESP, Setor de Neurofisiologia ClínicaSciEL