Analysis of electroencephalography brain rhythms in the reading process / Análise dos ritmos cerebrais de eletroencefalografia no processo de leitura

ABSTRACT Objective: To verify if, by three distinct quantifiers, the measured electroencephalographic signal at rest is different from the signal measured during a word reading situation, especially considering the faster rhythms, gamma and high-gamma, as it occurs in clinical rhythms (delta to beta). Methods: A total of 96 electroencephalographic signals measured from neurologically healthy volunteers were evaluated at two moments: resting and word reading. Each signal segment was measured by three quantifiers that separately assess normalized power, percent power, and right and left hemisphere coherence. The Mann-Whitney test was used to compare the results of the quantifiers in each brain range. Results: The gamma and high-gamma rhythms presented a more distinct behavior when comparing the analyzed moments (resting and reading) than the clinical rhythms. Conclusion: This finding contributes to the scarce literature on faster rhythms, which can contain information that is normally disregarded in neurological clinical practice.

RESUMO Objetivo: Verificar se, por meio de três quantificadores distintos, o sinal eletroencefalográfico medido em repouso é diferente do sinal medido durante o processo de leitura, especialmente considerando os ritmos rápidos, gama e supergama, assim como ocorre nos ritmos clínicos delta a beta. Métodos: Foram avaliados 96 sinais eletroencefalográficos medidos em voluntários neurologicamente saudáveis, em dois momentos: repouso e leitura de palavras. Cada trecho do sinal foi mensurado por três quantificadores que medem, de maneira isolada, a potência normalizada e a potência percentual, bem como a coerência entre os hemisférios direito e esquerdo. O teste estatístico de Mann-Whitney foi usado para comparar os resultados dos quantificadores em cada faixa cerebral. Resultados: Os ritmos gama e supergama apresentaram comportamento mais distinto entre os momentos analisados (repouso e leitura) que os ritmos clinicamente analisados. Conclusão: Esse achado contribui com a escassa literatura segundo a qual os ritmos rápidos podem conter informações que normalmente são descartadas na neurologia clínica.

Abnormal Sleep Delta Rhythm and Interregional Phase Synchrony in Patients with Restless Legs Syndrome and Their Reversal by Dopamine Agonist Treatment

BACKGROUND AND PURPOSE: The purpose of this study was to characterize abnormal cortical activity during sleep in restless legs syndrome (RLS) patients and to determine the effects of treatment with a dopamine agonist. Based on whole-brain electroencephalograms, we attempted to verify alterations in the functional network as well as the spectral power of neural activities during sleep in RLS patients and to determine whether the changes are reversed by treatment with pramipexole. METHODS: Twelve drug-naïve RLS patients participated in the study. Overnight polysomnography was performed before and after treatment: the first recording was made immediately prior to administering the first dose of pramipexole, and the second recording was made 12–16 weeks after commencing pramipexole administration. Sixteen age-matched healthy participants served as a control group. The spectral power and interregional phase synchrony were analyzed in 30-s epochs. The functional characteristics of the cortical network were quantified using graph-theory measures. RESULTS: The delta-band power was significantly increased and the small-world network characteristics in the delta band were disrupted in RLS patients compared to the healthy controls. These abnormalities were successfully treated by dopaminergic medication. The delta-band power was significantly correlated with the RLS severity score in the RLS patients prior to treatment. CONCLUSIONS: Our findings suggest that the spectral and functional network characteristics of neural activities during sleep become abnormal in RLS patients, and these abnormalities can be successfully treated by a dopamine agonist.

Cortical activity in tinnitus patients and its modification by phonostimulation

OBJECTIVE: The goal of this study was to observe spontaneous cortical activity and cortical activity modulated by tinnitus-matched sound in tinnitus patients and healthy subjects with no otoneurologic symptoms. METHOD: Data were prospectively collected from 50 tinnitus patients and 25 healthy subjects. Cortical activity was recorded in all subjects with eyes closed and open and during photostimulation, hyperventilation and acoustic stimulation using 19-channel quantitative electroencephalography. The sound applied in the tinnitus patients was individually matched with the ability to mask or equal the tinnitus. The maximal and mean amplitude of the delta, theta, alpha and beta waves and the type and amount of the pathologic EEG patterns were noted during each recording. Differences in cortical localization and the influence of sound stimuli on spontaneous cortical activity were evaluated between the groups. RESULTS: The tinnitus group exhibited decreased delta activity and increased alpha and beta activity. Hyperventilation increased the intensity of the differences. The tinnitus patients had more sharp-slow waves and increased slow wave amplitude. Sound stimuli modified the EEG recordings; the delta and beta wave amplitudes were increased, whereas the alpha-1 wave amplitude was decreased. Acoustic stimulation only slightly affected the temporal region. CONCLUSION: Cortical activity in the tinnitus patients clearly differed from that in healthy subjects, i.e., tinnitus is not a “phantom” sign. The changes in cortical activity included decreased delta wave amplitudes, increased alpha-1, beta-1 and beta-h wave amplitudes and pathologic patterns. Cortical activity modifications occurred predominantly in the temporal region. Acoustic stimulation affected spontaneous cortical activity only in tinnitus patients, and although the applied sound was individually matched, the pathologic changes were only slightly improved. .

Non-epileptiform EEG abnormalities: an overview / Anormalidades eletrencefalográficas não epileptiformes: uma visão geral

More than 80 years after its introduction by Hans Berger, the electroencephalogram (EEG) remains as an important supplementary examination in the investigation of neurological disorders and gives valuable and accurate information about cerebral function. Abnormal EEG findings may include ictal patterns, interictal epileptiform activity and non-epileptiform abnormalities. The aim of this study is to make an overview on the main non-epileptiform EEG abnormalities, emphasizing the pathologic findings and the importance of their recognition, excluding periodic patterns and EEG physiologic changes. Scientific articles were selected from MEDLINE and PubMed database. The presence of non-epileptiform EEG abnormalities provide evidence of brain dysfunction that are not specific to a particular etiology and may be related to a number of disorders affecting the brain. Although these abnormalities are not specific, they can direct attention to the diagnostic possibilities and guide the best treatment choice.

Mais de 80 anos após sua introdução por Hans Berger, o eletrencefalograma (EEG) permanece como importante exame complementar na investigação de transtornos neurológicas e fornece informações valiosas e precisas a respeito da função cerebral. Achados eletrencefalográficos anormais podem incluir padrões ictais, atividade epileptiforme interictal e anormalidades eletrencefalográficas não epileptiformes. O objetivo deste estudo é fazer uma revisão das principais anormalidades eletrencefalográficas não epileptiformes, enfatizando os achados patológicos e a importância de seu reconhecimento, excluindo padrões periódicos e alterações eletrencefalográficas fisiológicas. Foram selecionados artigos científicos por meio de pesquisa nas bases de dados MEDLINE e PubMed. A presença de anormalidades eletrencefalográficas não epileptiformes fornece evidências de disfunção cerebral, as quais não são específicas para uma etiologia particular e podem estar relacionadas a uma série de desordens que afetam o encéfalo. Embora essas anormalidades não sejam específicas, elas podem direcionar a atenção para as possibilidades diagnósticas e guiar a escolha do melhor tratamento.

Delta sleep instability in children with chronic arthritis

The objective of the present study was to evaluate the expression of a cyclic alternating pattern (CAP) in slow wave sleep (SWS) in children with the well-defined chronic syndrome juvenile idiopathic arthritis (JIA). Twelve patients (9-17 years of age), 7 girls, with JIA were compared to matched controls by age, pubertal stage and gender. After one night of habituation in the sleep laboratory, sleep measurements were obtained by standard polysomnography with conventional sleep scoring and additional CAP analyses. The sleep parameters of the JIA and control groups were similar for sleep efficiency (91.1 ± 6.7 vs 95.8 ± 4.0), sleep stage in minutes: stage 1 (16.8 ± 8.5 vs 17.8 ± 4.0), stage 2 (251.9 ± 41 vs 262.8 ± 38.1), stage 3 (17.0 ± 6.0 vs 15.1 ± 5.7), stage 4 (61.0 ± 21.7 vs 77.1 ± 20.4), and rapid eye movement sleep (82.0 ± 27.6 vs 99.0 ± 23.9), respectively. JIA patients presented nocturnal disrupted sleep, with an increase in short awakenings, but CAP analyses showed that sleep disruption was present even during SWS, showing an increase in the overall CAP rate (P < 0.01). Overall CAP rate during non-rapid eye movement sleep was significantly higher in pediatric patients who were in chronic pain. This is the first study of CAP in pediatric patients with chronic arthritis showing that CAP analyses can be a powerful tool for the investigation of disturbance of SWS in children, based on sleep EEG visual analysis.

Postoperative Electroclinical Features in Epilepsy Patients With Seizures After Anteromesial Temporal Resection

BACKGROUND: Anteromesial temporal resection (AMTR) is well established as effective in patients with intractable mesial temporal epilepsy. However, little electroclinical information is available relevant to poor surgical outcome after AMTR. We examined the postoperative electroclinical features based on postoperative MRI and video-EEG monitoring (VEM) in patients with poor surgical outcome. METHODS: We reviewed clinical features and postoperative VEM results in 20 patients with failure in AMTR. According to the postoperative electroclinical features, we classified them into mesial temporal (MT), bitemporal (BT), extramesial temporal (XMT), combined (C), and unclassified groups. The postoperative VEM results were compared among the groups. Surgical outcome was assessed in five patients who underwent reoperation. RESULTS: Patients comprised 6 MT, 2 BT, 6 XMT, 1 C, and 6 unclassified. Aura and automatism were more frequent in MT (50.0%, 83.3%) than in XMT (16.7%, 33.3%). Theta to delta rhythm, during the ictal onset and build-up period, was more frequent in MT (83.3%, 66.7%) than in XMT (33.3%, 33.3%). The ictal onset and build-up pattern of ictal EEG were most frequently localized to the frontotemporal region in MT (66.7%, 100.0%), while there was no predominantly localized region in XMT. The surgical outcome after reoperation was better in MT group than in XMT and C groups. CONCLUSIONS: Postoperative MRI and VEM are useful to assess the postoperative electroclinical features in failed AMTR. Reoperation of the residual mesiotemporal structures after confirming epileptogenic foci may have good surgical outcome.

Occipital intermittent rhythmic delta activity in absence epilepsy

Atividade occipital delta rítmica intermitente (AODRI) é considerada fator de bom prognóstico em crises de ausência típica (AT). Neste estudo relatamos a evolução eletroclínica de 14 pacientes com AT e AODRI que realizaram vídeo-EEG. Sete pacientes eram do sexo feminino; nove tinham epilepsia ausência da infância e os outros não apresentavam características eletroclínicas para classificação sindrômica de acordo com a classificação da ILAE (1989). Picnolepsia foi relatada em 13; AT foi o único tipo de crise em 13; um tinha crises generalizadas TCG e três, abalos mioclônicos durante AT. Monoterapia com VPA controlou as crises em 11, diVPA e ESM, em um cada. Após o controle das crises, o EEG normalizou em 10; em três, complexos de espícula-onda (CEO) persistiram, acompanhados por AODRI em um. Finalmente em outro, as crises não foram controladas, persistindo CEO e AODRI. Concluindo, observamos nesta série de AT e AODRI, com início antes dos 10 anos, picnolepsia freqüente e poucas crises TCG. VPA controlou as crises na maioria dos casos e o EEG normalizou em 76,92%. Sugerimos que AODRI possa ser considerada um fator de bom prognóstico em AT associada a CEO e de possível natureza epileptiforme, levando por sua vez, à investigação apropriada.

Using the histogram analysis method to assess the time-frequency features of rat EEG under different vigilance states / 生物医学工程学杂志

To investigate the non-stationary time-frequency features in rat Electroencephalogram (EEG) under different vigilance states, the methods of multi-resolution wavelet transform (WT) and statistical histogram analysis were used. EEGs of the freely moving rats were recorded with implanted electrodes under the vigilance states of waking, slow wave sleep (SWS) and rapid eye movement sleep (REM). The EEGs were firstly decomposed into four frequency components of delta, theta, alpha and beta by using multi-resolution wavelet transform. Then, the parameters of mean value, standard deviation, skewness and kurtosis of the logarithm power histograms and the power percentage histograms of each of the frequency components were calculated. The results showed that the distributions of the logarithm power histograms were not quite different from the normal distribution. However, most of the power percentage histograms were significantly different from the normal distribution. The results of one-way ANOVA indicated that there were significant differences in the parameter values of the histograms both among different states and among different frequency components. Moreover, Skewness and kurtosis of the logarithm power histograms of some characteristic waves in EEG, such as delta wave during SWS and theta wave during waking and REM, obtained high values. Thus, the histogram parameters of EEG WT components might become as quantitative measures to describe the dynamic time-frequency features of EEG.

Autoregressive model order property for sleep EEG / 生物医学工程学杂志

Traditional sleep scoring system describes the sleep EEG characterized by features in time domain as well as frequency domain. Power Spectral Density (PSD) is one of the well-used methods to observe the occurrence of specified rhythms. However, the parameter model based PSD estimation is used with the assumption that the model order is determined as low as possible through prior knowledge. This paper briefs the development of Autoregressive Model Order (ARMO) criterion, and provides the distribution of ARMOs for specified sleep EEG, which shows that ARMOs concentrate on several well separated regions that are indicative of the microstructure and transition states. This study suggests the promising perspective of ARMO as a special EEG feature for weighing complexity, randomness and rhythm components.

Semiologia eletroencefalográfica / Electroencephalographic semiology

O conhecimento semiológico rigoroso do eletroencefalograma é fundamental para a leitura e interpretação adequadas do seu registro. Este artigo valoriza os principais parâmetros das ondas, ritmos e atividades eletroencefalográficas. As características primárias físicas do ciclo, que é o elemento básico da onda, são a amplitude, tempo e forma e, as secundárias, de interesse eletroclínico, quantidade, variabilidade, localização, irradiação, reatividade, polaridade, simetria, sincronismo, modulação de amplitude e freqüência. São apresentadas as bandas de freqüência e os ritmos correspondentes. Mencionam-se o EEG de baixa voltagem, as ondas lentas patológicas e as lentificações que podem ser da atividade de base ou intermitentes ou contínuas. São também apresentados, além de sugestão de laudo o EEG e graduação das anormalidades, métodos de ativação do EEG (pela hiperventilação, sono e sua privação e estimulação fótica, auditiva e sensitiva) e os artefatos (extrafisiológicos-ambiental, instrumental e de eletrodo ou fisiológicos-oculares, miogênicos, cardíacos e de pulso, glossocinéticos, respiratórios, galvânicos/cutâneos e por obturações dentárias)

Neurocortical electrical activity tomography in chronic schizophrenics

Functional imaging of brain electrical activity was performed in 25 chronic medicated schizophrenics and 40 controls, analyzing the classical frequency bands (delta, theta, alpha, and beta) of 19-channel EEG during resting state to identify brain regions with deviant activity of different functional significances, using LORETA (Low Resolution Tomography) and SPM99 (Statistical Parametric Mapping). Patients differed from controls due to an excess of slow activity comprising delta + theta frequency bands (inhibitory pattern) located at the right middle frontal gyrus, right inferior frontal gyrus, and right insula, as well as at the bilateral anterior cingulum with a left preponderance. The high temporal resolution of EEG enables the specification of the deviations not only as an excess or a deficit of brain electrical activity, but also as inhibitory (delta, theta), normal (alpha), and excitatory (beta) activities. These deviations point out to an impaired functional brain state consisting of inhibited frontal and prefrontal areas that may result in inadequate treatment of externally or internally generated information

Eletrencefalograma quantitativo em escolares sadios: análise de frequências / Quantitative electroencephalography in healthy school-age children: analysis of band power

Abordaram-se, quantitativamente, parâmetros do eletrencefalograma e suas relaçöes com idade, sexo e fatores sócio-educacionais. Foram estudadas 162 crianças de 7 a 11 anos de idade sem problemas neurológicos, psiquiátricos ou déficit cognitivo em testes psicométricos. Foram submetidas a entrevista, exame clínico-neurológico, teste de Matrizes Progressivas de Raven, Teste de Desempenho Escolar e eletrencefalograma quantitativo durante a vigília, em repouso. Observou-se, com a idade, diminuiçäo das potências absoluta e relativa das faixas delta e teta assim como aumento da potência relativa alfa 2. Tais achados säo semelhantes aos de outras populaçöes da Europa, Asia e América do Norte. Observou-se, ainda, que as potências absolutas delta e, especialmente, alfa foram maiores nas crianças com melhor desempenho no Teste de Desempenho Escolar, de modo independente da idade e do sexo da criança e da escolaridade materna. Näo houve diferenças significativas da atividade elétrica cerebral segundo o sexo da criança e a escolaridade das mäes

Envelhecimento normal e EEG: alterações não específicas e padrões idade relacionados / Normal aging and EEG: non-específic abnormalities and age-related patterns

O EEG é potencialmente importante na avaliação do envelhecimento cerebral para o reconhecimento de alterações estruturais ou funcionais cerebrais com expressão clínica ou mesmo subclínica. No entanto, existem padrões não específicos ou idade-relacionados que precisam ser distintos para melhor discrime com doenças como a de Alzheimer ou cerebrovascular. O ritmo alfa no envelhecimento é propenso ao alentecimento, principalmente após os oitentas anos, e também à redução da amplitude, além de fragmentação, descontinuidade e difusão para as áreas anteriores. Alguns autores sugerem tendência à redução da reatividade visual. A banda mais rápida do ritmo beta tende a aumentar. O alentecimento principalmente através das ondas teta também tende a aumentar com o envelhecimento (episódios progressivamente mais freqüentes e de maior amplitude), mais nas regiões temporais, principalmente à esquerda. Alentecimento generalizado é consistentemente relacionado à deterioração intelectual senil, mas não o focal. Muitos desses achados podem estar relacionados a situações subclínicas vinculadas à hipertensão arterial, diabetes e arteriosclerose. Novas técnicas de neuroimagem e de EEG quantitativo podem colaborar no julgamento clínico dos padrões EEG variantes envelhecimento, assim como na compreensão da sua fisiopatogenia real

Tratamiento farmacológico del insomnio primario crónico: Análisis visual y espectral de los efectos del zolpidem sobre el electroencefalograma del sueño / Pharmacologic treatment of chronic primary insomnia: Visual and spectral analysis of the zolpidem effects on sleep EEG

Se realizó un estudio doble-ciego y aleatorizado para determinar los efectos del zolpidem o un placebo sobre el sueño en dos grupos de pacientes con un diagnóstico de insomnio primario crónico. Además, se determinaron los efectos del zolpidem sobre la estructura del sueño utilizando el análisis espectral. El zolpidem fue administrado a la dosis diaria de 10 mg durante 15 noches. En comparación con el placebo, el zolpidem redujo la latencia para el inicio del sueño y el tiempo de vigilia luego del comienzo del sueño, mientras que el tiempo total del sueño y su eficiencia se incrementaron. El análisis visual del sueño con ondas lentas (etapas 3 y 4) no mostró cambios significativos de los valores correspondientes a esta variable. El análisis espectral del electroencefalograma nocturno permitió observar que la densidad del espectro de potencia del sueño no-REM estuvo aumentada en forma significativa en la banda de frecuencia de 0.3-10 Hz en el grupo zolpidem durante las primeras dos horas del registro. Otras bandas de frecuencia en el rango delta mostraron pequeños cambios que no fueron significativos

The effect of delta sleep-inducing peptide on the EEG and power spectra in rat.

The effects of delta sleep-inducing peptide (DSIP) on the EEG and power spectra of adult male Wistar rats (b.w. 180-220 g) were studied by power spectra analyses of EEG wave forms recorded continuously for 12 h after DSIP administration. The animals were given DSIP i.p. (1 mg/kg). Saline-injected rats served as the corresponding control. Recorded bursts of high amplitude EEG in the 1-9 Hz range (delta and theta) were found to be more frequent in DSIP-treated animals, while power spectra and (delta) wave activity were enhanced in comparison with the control and a statistically significant increase was registered in all experimental points after DSIP (2 h P < 0.05; 4 h P < 0.05; 5 h P < 0.05; 6 h P < 0.05; 7 h P < 0.01; 11 h P < 0.05). In addition, DSIP significantly elevated both the EEG output in the (delta) range and sleep activity. These results suggest that DSIP should be considered as a potential agent for the treatment of sleep disturbances in human medicine.

Significado fisiológico dor parâmetros de freqüência e amplitude do EEG humano e valor informativo comparativo das análises espectral e de periódo / Physiological meaning of frequency and amplitude parameters in human ECG and comparative informative value of spectral and the period analysis

Em trechos prolonados do EEG, verificamos, através de análise fatorial, que a freqüência e a amplitude da análise de período (em 4 faixas padrão) fornecem parâmetros com diferentes significados fisiológicos. Em determinadas tarefas psicofisiológicas e clínicas (relacionadas ao estudo da atividade mental), estes parâmetros aparentam ser mais adequados e informativos do que os mais usados características espectrais dessas mesmas faixas.

Atypical EEG pattern in children with absence seizures

Estudamos quatro crianças com o diagnóstico de crises de ausência (epilepsia generalizada primária) e com atividade delta generalizada no EEG, durante crises provocadas pela hiperpnéia. A ausência de descargas generalizadas por conplexos ponta-onda a 3 Hz, durante as crises de nossos pacientes, é achado incomum. Todas as crianças tiveram completo controle de suas crises com o valproato, assim como o desaparecimento das alteraçöes no EEG. Concluimos que a atividade delta generalizada observada no EEG de crianças durante a hiperpnéa nem sempre deve ser vista como achado normal, podendo ser um evento crítico da crise generalizada ausência

Especializaçäo funcional hemisférica na afasia motora: achados neurofisiológicos ao mapeamento eletrencefalográfico computadorizado sob estimulaçä sonora musical e verbal: estudo de dois casos / Hemispheric functional specialization in motor aphasia: neurophysiologic findings with electroencephalographic brain mapping during musical and oral sonours stimulation: study of 2 cases

Este estudo diz respeito à atividade elétrica cerebral durante estimulaçäo auditiva em dois pacientes afásicos, um com afasia clássica (lesäo no hemisfério esquerdo) e outro com afasia cruzada (lesäo no hemisfério direito). Ambos foram submetidos ao teste de estimulaçäo auditiva dicótica (consoante-vogal-consoante) e de audiçäo musical (canto gregoriano) durante mapeamento eletrencefalográfico cerebral. Encontramos, em ambos, grande proporçäo da frequência delta e potência no hemisfério näo lesado, durante a estimulaçäo dicótica e musical. Alé disso, foi observado aumento na frequência de atividade alfa somente no hemisfério näo lesado, restrito à regiäo do lobo temporal. Esses achados sugerem um interessante campo de pesquisa acerca da medida de correlatos neurofisiológicos de estimulaçäo auditiva e de atividade elétrica cerebral na afasia

Electroencephalogram base rhythm in AIDS patients

We studied the EEG of 73 patients diagnosed with HIV infection, with or without secondary complications. Sixty-eight belonged to CDC (Center for Disease Control) group IV and 38 presented signs or symptoms of encephalic neurological impairment. Rhythms constituting base activity were alpha (65.75%), beta (13.70%), theta (12.33%), and delta (8.22%). The alpha rhythm presented two modes: slow (8 to 9 Hz) in 25/48 or 52.08% of the cases and not-slow (> 9 to 13 Hz) in 23/48 or 47.92% of the cases. The alpha slow-mode has been observed in about 10 to 15% of the normal population, with the 8 Hz frequency being found in only 1% of the normal adult population, which suggests that in some manner HIV is implicated in the slowing-down of the EEG base rhythm in AIDS patients. The patients from CDC group IV with encephalic neurological involvement presented a base rhythm significantly lower than those with non-encephalic involvement or the absence of neurological impairment.

Brain mapping in suicidal and non-suicidal depressives

Reports and experience reveal the fact that 15% of major depressive patients will commit suicide. Do those suicidal depressives constitute a special sub-group of depressives? Can we predict by some markers those with high suicidal risk? CT findings, neuropsychological testing and EEC showed abnormalities in a sub-group of depressives. Previous findings have reported a low 5 HIAA of the CSF of suicidal or violent patients. Through BEAM studies, previous authors have attempted to separate paranoid and non-paranoid depressives and depersonalized and non-depersonalized depressives. This study is an attempt to differentiate between high risk suicidal and non-suicidal depressives through BEAM. Our study showed encouraging results in that, with more cases, more modifications and more statistical analysis regarding amplitude, power and distribution, we can develop a possible neurophysiological marker for high risk suicidal depressives thus giving better prophylaxis and caution. Our findings showed that 64% of suicidal depressives show the right parieto-occipital dysfunction seen in the non-suicidal depressives with temporal extension