Valoración del cociente Theta/Beta en el electroencefalograma cuantificado de los trastornos por déficit de atención e hiperactividad / Measurement of the theta / beta ratio with the quantified electroencephalogram in attention-deficit hyperactivity disorders

El cociente Theta-Beta (T/B) del electroencefalograma cuantificado (EEGQ) de los pacientes con trastorno por déficit de atención e hiperactividad (TDAH) constituye una variable del EEG característica del trastorno primario con una precisión global del 89%. El objetivo de este estudio es medir el cociente T/B de una población de con TDAH y los efectos del tratamiento farmacológico con psicoestimulantes y no psicoestimulantes sobre el cociente T/B. La muestra estaba formada por 85 sujetos de entre 6 y los 18 años (68 niños y 17 niñas) con el diagnóstico de TDAH de subtipo inatento y combinado, según los criterios del DSM-V. Se les realizó un EEGQ con medición del cociente T/B antes y después de 6 meses de tratamiento con fármacos psicoestimulantes y no psicoestimulantes. Se compararon ambos grupos mediante la prueba de rangos con signo de Wilcoxon para muestras relacionadas. En el 86% de los casos el cociente T/B fue elevado respecto de los valores normales para la edad. La reducción en el cociente T/B fue significativa en el grupo tratado con psicoestimulantes aunque la reducción con los no psicoestimulantes no fue significativa. En conclusión, se confirma la elevación del cociente T/B en los pacientes con TDAH. Los fármacos psicoestimulantes disminuyen de forma significativa el cociente T/B elevado en los pacientes con TDAH tras 6 meses de tratamiento.

Theta-Beta (T / B) ratio of the quantified electroencephalogram (EEGQ) in patients with attention deficit hyperactivity disorder (ADHD) constitutes a characteristic EEG variable of the primary disorder with an overall accuracy of 89%. The objective of this study was to measure the T/B ratio in a sample of patients with ADHD and the effects of the treatment with psychostimulants and non-psychostimulants on the T/B ratio. The sample consisted of 85 children between 6 and 18 years (68 males and 17 females) with the diagnosis of the inattentive and combined subtype of ADHD, according to the criteria of the DSM-V. An EEGQ was performed with measurement of the T/B ratio before and after 6 months of treatment with psychostimulant and non-psychostimulant drugs. Both groups were compared using the Wilcoxon signed range test for related samples. The results showed that 86% of the cases had a T/B ratio above the normal values for the age of them. The reduction in the T/B ratio was statistically significant in the group of patients treated with psychostimulants. The reduction of non-psychostimulants was not significant. In conclusion, we confirmed the high T/B ratio in patients with ADHD. Psychostimulant drugs decrease the elevated T/B ratio in patients with ADHD after 6 months of treatment.

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.

Influence of Medication on the Oscillatory and Dynamic Characteristics of Subthalamic Local Field Potentials in Patients with Parkinson's Disease / 生物医学工程学杂志

The dysfunction of subthalamic nucleus is the main cause of Parkinson's disease. Local field potentials in human subthalamic nucleus contain rich physiological information. The present study aimed to quantify the oscillatory and dynamic characteristics of local field potentials of subthalamic nucleus, and their modulation by the medication therapy for Parkinson's disease. The subthalamic nucleus local field potentials were recorded from patients with Parkinson's disease at the states of on and off medication. The oscillatory features were characterised with the power spectral analysis. Furthermore, the dynamic features were characterised with time-frequency analysis and the coefficient of variation measure of the time-variant power at each frequency. There was a dominant peak at low beta-band with medication off. The medication significantly suppressed the low beta component and increased the theta component. The amplitude fluctuation of neural oscillations was measured by the coefficient of variation. The coefficient of variation in 4-7 Hz and 60-66 Hz was increased by medication. These effects proved that medication had significant modulation to subthalamic nucleus neural oscillatory synchronization and dynamic features. The subthalamic nucleus neural activities tend towards stable state under medication. The findings would provide quantitative biomarkers for studying the mechanisms of Parkinson's disease and clinical treatments of medication or deep brain stimulation.

Alteration of neural oscillations in hippocampal CA3 area in the fast avoidance response rat before and after electric shock avoidance training / 生理学报

The purpose of the present study is to explore the relationship of spatial learning ability and specific electrical activities of neural oscillations in the rat. The fast and general avoidance response groups were selected on the basis of the animals' responses to the electric shock in Y type maze, and their local field potentials (LFPs) of hippocampal CA3 area were recorded by wireless telemetry before and after shock avoidance training, respectively. The components of neural oscillations related to spatial identifying and learning ability were analyzed. The results showed that, compared with the general avoidance response group, the fast avoidance response group did not show any differences of LFPs in hippocampal CA3 area before electric shock avoidance trial, but showed significantly increased percentages of 0-10 Hz and 30-40 Hz rhythm in right hippocampal CA3 area after the shock avoidance training (P < 0.01 or P < 0.05). Fast Fourier transform showed that percentage increase of 0-10 Hz band occurred mainly in θ (3-7 Hz) frequency, and 30-40 Hz frequency change was equivalent to the γ1 band. Furthermore, compared with those before training, only the percentages of β, β2 (20-30 Hz) and γ1 rhythm increased (P < 0.01 or P < 0.05) in fast avoidance response rats after training, while the θ rhythm percentage remained unchanged. In contrast, θ rhythm percentage and the large amplitude (intensity: +2.5 - -2.5 db) θ waves in right CA3 area of general avoidance response rats were significantly reduced after training (P < 0.01). These results suggest that the increased percentages of β2 and γ1 rhythm and high-level (unchanged) percentage of θ rhythm in the right hippocampus CA3 area might be related to strong spatial cognition ability of fast avoidance response rats.

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. .

Alzheimer's disease qEEG: spectral analysis versus coherence. which is the best measurement? / EEGq na doença de Alzheimer: análise espectral versus coerência. O que é melhor?

There is evidence in electroencephalography that alpha, theta and delta band oscillations reflect cognitive and memory performances and that quantitative techniques can improve the electroencephalogram (EEG) sensitivity. This paper presents the results of comparative analysis of qEEG variables as reliable markers for Alzheimer's disease (AD). We compared the sensitivity and specificity between spectral analysis (spectA) and coherence (Coh) within the same group of AD patients. SpectA and Coh were calculated from EEGs of 40 patients with mild to moderate AD and 40 healthy elderly controls. The peak of spectA was smaller in the AD group than in controls. AD group showed predominance of slow spectA in theta and delta bands and a significant reduction of inter-hemispheric Coh for occipital alpha 2 and beta 1 and for frontal delta sub-band. ROC curve supported that alpha band spectA was more sensitive than coherence to differentiate controls from AD.

Há evidências de que as oscilações das bandas teta, alfa e delta no eletroencefalograma podem refletir diferenças na cognição e memória; a sensibilidade deste método diagnóstico pode ser melhorada por técnicas de quantificação. Comparamos a sensibilidade e especificidade entre a análise espectral (spectA) e coerência (Coh) dentro do mesmo grupo de pacientes com doença de Alzheimer (DA) e contra um grupo controle. SpectA e Coh foram calculadas a partir de EEGs de 40 pacientes com DA leve a moderada e 40 idosos saudáveis. O pico do espectro foi menor no grupo DA que nos controles. O grupo DA também apresentou um espectro mais lento nas bandas teta e delta e menor coerência inter-hemisférica para as sub-bandas alfa 2 e beta 1 posterior e delta frontal. A curva ROC suporta que a análise espectral da banda alfa foi mais sensível que a coerência para diferenciar controles de DA.

Modelo de hipnosis muy profunda colectiva y simultánea para el estudio de funciones cognitivas / Very deep, collective and simultaneous hypnosis model for the study of cognitive functions

Se realizó un estudio analítico experimental durante el 2009, que incluyó a estudiantes de segundo año de licenciatura en enfermería de la Universidad de Ciencias Médicas de Granma, seleccionados mediante el método aleatorio simple, para lo cual se creó un modelo de hipnosis muy profunda, grupal y simultánea, a fin de controlar los fenómenos hipnóticos por etapas y estudiar la memoria. Se utilizaron el test de las 10 palabras como indicador y la prueba de los signos para la validación estadística de los hallazgos. Los resultados de la memorización y su evocación en hipnosis muy profunda durante la vigilia habitual fueron mejores que los de la memorización en vigilia recordada y viceversa. La aplicación del paradigma fisiológico para el diagnóstico del estado de conciencia fue útil para definir la etapa muy profunda, durante la cual no hubo sincronización del ritmo alfa por apertura de los ojos en ese estado de conciencia. Los ritmos alfa y beta devinieron típicos del estado hipnótico.

An experimental-analytic study which included second year students from the Bachellor in Nursery career from the Medical University in Gramma was carried out during 2009. They were selected by means of the simple random method, for which a model of very deep, grupal and simultaneous hypnosis was created, in order to control the hypnotic phenomena in stages and to study memory. The 10 words test as indicator and the signs test for the statistical validation of the findings were used. The results of the memorization and their evocation in deep hypnosis during the habitual wakefulness were better than those of the memorization in recalled wakefulness and vice versa. The application of the physiologic paradigm for the diagnosis of the consciousness state was useful to define the very deep stage, during which there was not synchronization of the alpha rhythm due to the opening of the eyes in that consciousness state. The alpha and beta rhythms became typical of the hypnotic state.

Changes in cortical relative power in patients submitted to a tendon transfer: a pre and post surgery study

The aim of this study is analyze possible modifications in the cerebral cortex, through quantitative electroencephalography (qEEG) in patients submitted to a tendon transfer procedure (posterior tibialis) by the Srinivasan's technique. Four subjects (2 men and 2 women), 49.25 age average (SD±21.4) were studied. All subjects have been through surgical procedure due to leprosy and had, at least, two years of drop foot condition. The qEEG measured the electrocortical activity (relative power) between 8 and 25 Hz frequencies pre and post surgery. A paired t test analyzed all data (p<0,05). The results show significant alterations in the alpha relative power, electrodes F7 (p=0.01) and F8 (p=0.021). Altogether, based on findings of the current literature, we can conclude that the tendon transfer procedure suggests electrocortical alterations sensitive to specific qEEG bands.

O objetivo deste estudo é analisar possíveis modificações no córtex cerebral, através da electrencefalografia quantitativa (EEGq), em pacientes submetidos a um procedimento de transferência de tendão (tibial posterior) pela técnica de Srinivasan. Quatro sujeitos (2 homens e 2 mulheres), com média de idade de 49,25 anos (±21,4 DP) foram estudados. Todos os sujeitos realizaram o procedimento cirúrgico devido a hanseníase e tinham, pelo menos, dois anos de pé caído. O EEGq mediu a atividade electrocortical (potencia relativa) entre freqüências de 8 e 25 Hz, no pré e pós-operatório. Um teste t pareado analisou todos os dados (p<0,05). Os resultados mostram alterações significativas na potência relativa em alfa, nos elétrodos F7 (p=0,01) e F8 (p=0,021). Baseados em recentes achados na literatura, podemos concluir que o procedimento de transferência de tendão sugere alterações eletrocorticais sensíveis às freqüên-cias específicas do EEGq.

Beta and alpha electroencephalographic activity changes after acute exercise

Exercise has been widely related to changes in cortical activation and enhanced brain functioning. Quantitative electroencephalography (qEEG) is frequently used to investigate normal and pathological conditions in the brain cortex. Therefore, the aim of the present study was to observe absolute power alterations in beta and alpha frequency bands after a maximal effort exercise. Ten healthy young volunteers were submitted to an eight-minute resting EEG (eyes closed) followed by a maximal exercise test using a mechanical cycle ergometer. Immediately after the exercise, another identical eight-minute EEG was recorded. Log transformation and paired student's t-test compared the pre and post exercise values (p<0.05). Results indicated a significant absolute power increase in beta after exercise at frontal (Fp1, F3 and F4) and central (C4) areas, which might be related to increased cortical activation.

A atividade física vem sendo relacionada com ativação cortical e melhor funcionamento do cérebro. A eletrencefalografia quantitativa (EEGq) é freqüentemente usada para investigar condições normais e patológicas do córtex cerebral. Sendo assim, o objetivo do presente estudo foi observar alterações na potência absoluta nas bandas de freqüência alfa e beta após um exercício de esforço máximo. Dez voluntários jovens e saudáveis foram submetidos a oito minutos de EEG antes e após um teste de esforço máximo em cicloergômetro. As transformações para o log e o teste t de Student foram utilizados para comparar as respostas eletrencefalográficas entre os momentos pré e pós exercício. Foi observado aumento significativo na potência absoluta de beta após o exercício nos eletrodos frontais (Fp1, F3, F4) e centrais (C4). Este resultado pode estar associado a alterações fisiológicas e ao aumento da ativação cortical.

Coerência espectral do eletrencefalograma em pacientes submetidos a transposição tendinosa: estudo pré e pós-operatório / EEG spectral coherence at patients submitted to tendon transfer surgery: study pre and post surgery

A transferência tendinosa do músculo tibial posterior é intervenção cirúrgica bastante utilizada na ortopedia para correção do pé caído por seqüela de hanseníase. Poucos modelos propuseram investigações mais significativas sobre os fenômenos plásticos cerebrais nas transferências tendinosas. O presente estudo teve como objetivo analisar a coerência espectral (CE) na Eletroencefalografia (EEG) em pacientes submetidos a transferência do tendão do tibial posterior pela técnica de Srinivasan através da EEG quantitativa (EEGq). A amostra foi composta de quatro sujeitos com pé caído devido a seqüela de hanseníase. Os parâmetros de CE do EEG foram quantificados no momento pré e pós-operatório. Os resultados mostraram que houve efeito principal para o fator momento, significativo, no par de eletrodos C3-CZ, com aumento da coerência. Entretanto, os achados da ANOVA não revelaram interação significativa entre bandas versus momento. A recuperação funcional promovida por tal cirurgia parece gerar alterações corticais.

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)

Post-cardiorespiratory arrest beta-alpha coma: an unusual electroencephalographic phenomenon.

The presence of frontally-dominant alpha pattern in the EEG is common in patients with coma due to trauma, toxic-metabolic causes and following cardiorespiratory arrest. Diffuse beta activity following resuscitation after a cardiac arrest is not well recognized. We report a case of coma in a 3-year-old girl who had a cardiac arrest from which she was revived. Initial EEG showed diffuse beta activity, which later evolved to predominantly alpha activity. The possible mechanisms involved in the generation of such rhythms are discussed. Transition of EEG activity from faster to slower frequencies is suggested as an adverse prognostic factor in post-cardiorespiratory arrest coma.

Normal electroencephalogram and benign variants

Normal and variant EEG patterns often simulate abnormalities and their misinterpretation can lead to harmful misdiagnoses of epilepsy. Consequently, expertise in these phenomena is fundamental for patient safety. Mastery of normal features must include the Alpha rhythm, Mu rhythm, beta activity, slow activity, posterior slow waves of youth, Lambda waves, hyperventilation and photic responses, drowsy patterns, vertex waves, sleep spindles, K-complexes and positive occipital sharp transients of sleep. Features clearly outside of and unequivocally distinct from the abundantly wide range of normal are possibly abnormal. However, there are several distinctive benign variant patterns that resemble epileptiform abnormalities or seizure discharges, but which are not associated with epilepsy. Clinical diagnosis must exclude these insignificant patterns, which include small sharp spikes, 14 and 6 Hz positive bursts, 6 Hz "phantom" spike-and-wave, wicket waves, rhythmic temporal theta bursts of drowsiness, subclinical rhythmic electrographic discharges of adults, midline theta and frontal arousal rhythm. Proper normal and variant pattern recognition is precise and criteria-based rather than subjective. Because amplitude and sharpness per se are insufficient discriminators, analysis also considers frequency, distribution, morphology, polarity, state-dependence, reactivity and symmetry. This illustrated review summarizes multi-factorial criteria that identify some normal and benign variant phenomena

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

EEG alpha desynchronization from rest to silent reading in school children

Objetivo: estudiar la asimetría cerebral en el electroencefalograma (EEG) durante la realización de una tarea de lectura silente. Métodos: se estudió un grupo de escolares durante una tarea de lectura silente buscando lateralización cerebral para el procesamiento verbal, hipotetizando que hay una desincronización asimétrica en la banda alfa provocada por la actividad cognoscitiva. Se estudiaron 25 escolares masculinos de 9-10 años con nivel de lectura adecuado a su edad, provenientes de escuelas públicas y privadas de la Ciudad de México. Se les realizó un estudio de EEG de 16 canales, los registros fueron realizados en reposo con los ojos cerrados y posteriormente durante la lectura en silencio de un texto con material acorde a su edad. El EEG fue analizado por medio de la transformada rápida de Fourier. Se calculó la potencia relativa por espectro de frecuencia dividido en las bandas: delta, theta, alfa, beta-1, beta-2, beta-3. Se compararon los datos de reposo y lectura en las bandas alfa y beta. Resultados: se observaron diferencias significativas en la distribución regional de la potencia relativa durante la lectura asociadas a un reducción generalizada de la actividad alfa, principalmente en el hemisferio izquierdo, así como un incremento frontal de los ritmos beta-2 y beta-3 durante la lectura. Conclusiones: la lectura silente puede producir una desincronización lateralizada del EEG con una reducción de la actividad alfa de predominio en el hemisferio izquierdo; así como, un aumento de los ritmos beta frontales, estas zonas son de conocida participación en el procesamiento del lenguaje.

Effects of Intravenous Anesthetics on EEG Spectral Analysis during Cesarean Section / 대한마취과학회지

BACKGROUND: Anesthesia induces the spectral changes in EEG. Attempts to relate these spectral changes to adequacy of anesthesia have been hindered due to the complex waveforms of EEG. The objective of this investigation is to monitor the awareness of patients during cesarean section by means of EEG spectral analysis. METHODS: 20 patients for cesarean section aged from 24 to 39 and ASA class I or II, were maintained with O2(50%)-N2O(50%)-enflurane(0.8%). And they were administered with midazolam(0.07 mg/kg) in group I(n=6), fentanyl(1 microgram/kg) in group II(n=7), and fentanyl(2 microgram/kg) in group III(n=7) after birth. The density of each spectral band in EEG (delta 1-3.25 Hz, theta 3.5-7.75 Hz, alpha 8-12.15 Hz and beta 13-31.75Hz) was analyzed to derive total density, delta ratio and median power frequency. RESULTS: The spectral data demonstrated that the alpha rhythm was dominant in pre-induction period and beta rhythm was abundant both in the immediate post-induction period and after birth for all three groups. Delta ratio and median power frequency decreased after injection of midazolam and fentanyl in all three groups. None of patients could recall the memory about experience during cesarean section. CONCLUSIONS: These findings indicate that EEG spectral analysis is potentially useful to determine the changes of cerebroelectrical activity but difficult to monitor the awareness of patients during cesarean section.

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

Electroencephalographic findings in normal children with poor academic achievement

Se investiga las actividades EEG normales, fronterizas y anormales en 132 niños "normales" que atendieron regularmente al 2§ y 4§ año de una escuela primaria federal en la Ciudad de México; con el objeto de determinar hasta que punto del EEG convencional pudo proporcionar datos subclínicos en los niños con pobre rendimiento escolar (PRE) y aquellos con una historia clínica patológica (AP) y en los controles (C). Se realizó un análisis comparativo de los signos EEG principales entre 2 grupos principales (PRE y C) y 4 subgrupos (PRE + AP, PRE + NoAP, C + AP, C + NoAP). 1.- Los signos anormales fueron significativamente mas frecuentes en el PRE que en el C; y el Pre + AP que en C + AP. 2.-Los signos normales atípicos consistentes en una actividad alfa de gran amplitud y asimetría inconstante, y los signos normales focales paroxisticos y no paroxisticos se encontraron solamente en los grupos PRE y PRE + AP. 3.- La "ondas de sueño" fronterizas se encontraron solamente en los grupos PRE + APy PRE + NoAP; mientras que los potenciales polifásicos solamente se encontraron en los grupos PRE + APyC + AP. 4.- La respuesta excesiva a la hipertiventilación fue significativamente más frecuente en el grupo C que en el PRE y en el C + No AP que en el PRE + AP