Generalized periodic EEG activity in two cases of neurosyphilis.

Neurosyphilis is a recognized cause of epileptic seizures and cognitive impairment, but is not usually associated with the finding of generalized periodic activity in the EEG. We report two similar cases characterized by progressive cognitive impairment followed by partial complex seizures, in whom the EEG showed generalized periodic activity. Both cerebrospinal fluid and the response to penicillin therapy confirmed the diagnoses of neurosyphilis in the two cases. The finding of EEG generalized periodic activity in patients with cognitive or behavioral disorders is usually associated with Creutzfeldt-Jakob disease, although there are other conditions, some of them potentially reversible, which may also present this EEG abnormality. Neurosyphilis has tended not to be included among them, and our present findings support the importance of first ruling out neurosyphilis in those patients with cognitive or behavioral disorders associated with generalized periodic epileptiform discharges.

Acute neurophysiological effects of the hypnotic zolpidem in healthy volunteers.

INTRODUCTION: The imidazopyridine zolpidem is a hypnotic drug with relative selectivity for the benzodiazepine (BZP) type 1 receptor subtypes displaying a different biochemical structure to that of BZPs. Little is known of its electrophysiological effects. PURPOSE: The aim of the present study was to investigate the acute neurophysiological effects of clinical oral doses of zolpidem. METHODS: This was a double blind, independent group design study. Thirty-six young, healthy volunteers were randomly allocated to one of three groups--zolpidem (5 mg and 10 mg) and placebo. In addition to ERPs, behavioural measures were used to examine sedative effects of the drug. RESULTS: ERPs were affected in a similar way to that described after sedative/hypnotic drug ingestion: increased N2 and P3 latencies and decreased N2 and P3 amplitudes. However, contrary to what is expected of a hypnotic drug, there was no change with N1 while P2 amplitude increased after the highest dose. CONCLUSIONS: Because zolpidem showed different effects in different components, it seems to first enhance or preserve initial orienting (no change in N1), after an increase of P2 and then drastically diminish resource allocation (affecting N2 and P3 latencies and amplitudes). The study with ERPs, therefore, allows a more direct "moment to moment" investigation of finer mechanisms of changes in cerebral processes underlying the acute ingestion of the drug in question. The effects on N2 and P3 amplitudes and latencies were similar to those of other sedative/hypnotic drugs. However, zolpidem led to an unexpected increase in P2 amplitude; this effect may be related to its selective receptor binding profile and warrants further research.

[EEG recording after sleep deprivation in a series of patients with juvenile myoclonic epilepsy].

Seizures in Juvenile Myoclonic Epilepsy (JME) are dependent on the sleep-wake cycle and precipitant factors, among which sleep deprivation (SD) is one of the most important. Still an under diagnosed syndrome, misinterpretation of the EEGs contributes to diagnostic delay. Despite this, a quantitative EEG investigation of SD effects has not been performed. We investigated the effect of SD on EEGs in 41 patients, aged 16-50 yr. (mean 25.4), who had not yet had syndromic diagnosis after a mean delay of 8.2 yr. Two EEG recordings separated by a 48-hour interval were taken at 7 a.m. preceded by a period of 6 hours of sleep (routine EEG) and after SD (sleep-deprived EEG). The same protocol was followed and included a rest wakefulness recording, photic stimulation, hyperventilation and a post-hyperventilation period. The EEGs were analyzed as to the effect of SD on the number, duration, morphology, localization and predominance of abnormalities in the different stages. A discharge index (DI) was calculated. Out of the 41 patients, 4 presented both normal EEG recordings. In 37 (90.2%) there were epileptiform discharges (ED). The number of patients with ED ascended from 26 (70.3%) in the routine EEG to 32 (86.5%) in the sleep-deprived exam. The presence of generalized spike-wave and multispike-wave increased from 20 (54.1%) and 13 (35.1%) in the first EEG to 29 (78.4%) and 19 (51.4%) in the second, respectively (p<0.05 and p<0.01). As to localization, the number of generalized, bilateral and synchronous ED increased from 21 (56.8%) to 30 (81.1%) (p<0.01). The DI also increased; while 8 patients (21.6%) presented greater rate in the routine EEG, 25 (67.6%) did so in the sleep-deprived EEG mainly during somnolence and sleep (p<0.01). Moreover, the paroxysms were also longer in the sleep-deprived EEG. Sleep-deprived EEG is a powerful tool in JME and can contribute significantly to the syndromic characterization of this syndrome.

A comparison between averaged spikes and individual visually-analyzed spikes in rolandic epileptiform discharges.

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.

Generalized periodic EEG activity in two cases of neurosyphilis

Neurossífilis é uma causa conhecida de crises convulsivas e de comprometimento cognitivo, mas não é associada geralmente a atividade periódica generalizada no eletroencefalograma (EEG). Relatamos dois casos similares caracterizados por declínio cognitivo progressivo seguido de crises parciais complexas, em que o EEG mostra a atividade periódica generalizada. O líquido cefalorraquidiano e uma boa resposta à terapia com penicilina confirmaram os diagnósticos de neurossífilis nos dois casos. Achados de atividade periódica generalizada no EEG de pacientes com distúrbios cognitivos ou de comportamento são associados geralmente com a doença de Creutzfeldt-Jakob, embora haja outras circunstâncias, algumas delas potencialmente reversíveis, que podem também apresentar esta anormalidade no EEG. A neurossífilis tende a não ser incluída entre eles, e nossos achados sustentam a importância de afastar o diagnóstico de neurossífilis naqueles pacientes com declínio cognitivo ou comportamental associados com as descargas periódicas generalizadas no EEG.

EEG recording after sleep deprivation in a series of patients with juvenile myoclonic epilepsy

Na epilepsia mioclônica juvenil (EMJ), uma síndrome epiléptica ainda subdiagnosticada, as crises são dependentes do ciclo vigília-sono e de fatores precipitantes, entre os quais a privação de sono (PS) é um dos mais importantes. A interpretação inadequada dos EEGs contribui para atraso no diagnóstico. Ainda não foi realizada investigação quantitativa sobre os efeitos da PS. Avaliamos o efeito da PS nos EEGs de 41 pacientes entre 16 e 50 anos (média 25,4) com EMJ em dois registros eletrencefalográficos, separados por intervalo de 48 horas. Os exames foram realizados às 7 horas da manhã, precedidos por um período de 6 horas de sono (EEG de rotina) e após PS (EEG com PS). Seguimos o mesmo protocolo que incluiu o registro em vigília em repouso, fotostimulação, hiperventilação e pós hiperventilação. O efeito da PS foi analisado sobre o número, duração, morfologia, localização e predominância das anormalidades nos diferentes estágios. Calculamos o índice de descargas por minuto. Dos 41 pacientes, 4 tiveram ambos os registros normais. Em 37 (90,2%) houve algumas descargas epileptiformes (DE). O número de pacientes com DE ascendeu de 26 (70,3%) no EEG de rotina para 32 (86,5%) no exame em PS. A presença de descargas de espícula-onda generalizadas e multispícula-onda aumentou de 20 (54,1%) e 13 (35,1%) no primeiro EEG para 29 (78,4%) e 19 (51,4%) no segundo, respectivamente (p<0,05 e p<0,01). Quanto à localização, o número de descargas ascendeu de 21 (56,8%) para 30 (81,1%) (p<0,01). O índice de descargas (ID) também aumentou; enquanto 8 pacientes (21,6%) apresentaram ID maior no EEG de rotina, 25 (67,6%) o tiveram no EEG em PS, principalmente durante sonolência e sono (p<0,01). Ainda mais, os paroxismos também foram mais longos no EEG em PS. EEG em PS é um instrumento poderoso para o diagnóstico de EMJ podendo contribuir significantemente na caracterização desta síndrome.

A comparison between averaged spikes and individual visually-analyzed spikes in rolandic epileptiform discharges

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 percent of them; in the remaining 9 averaged discharges, up to 20 percent 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 percent of its individual discharges, whereas up to 45 percent 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

Recomendaçöes técnicas para o registro do eletrencefalograma (EEG) na suspeita da morte encefálica / Technical recomendations for the electroencephalogram (EEG) recording in suspected brain death

Neste trabalho, desenvolvido por uma comissao nomeada pela Sociedade Brasileira de Neurofisiologia Clínica, sao apresentadas as recomendaçoes referentes ao registro do eletrencefalograma (EEG) nos casos de suspeita de morte encefálica, enfatizando que, apesar do necessário respeito aos parâmetros técnicos, o método nao visa substituir o exame neurológico, mas complementá-lo.

Recomendaçöes para o registro/interpretaçäo do mapeamento topográfico do eletrencefalograma e potenciais evocados: parte II: correlaçöes clínicas / Guidelines for recording/analyzing quantitative EEG and evoked potentials: part II: clinical aspects

O EEG digital (DEEG) e o quantitativo (QEEG) representam métodos recém desenvolvidos na prática clínica que, além da utilidade didática e em pesquisa, também mostram importância clínica. As aplicaçoes clínicas sao enumeradas a seguir: 1. O DEEG representa um substituto estabelecido para o EEG convencional, pois acrescenta claros avanços técnicos. 2. Algumas técnicas do QEEG sao consideradas estabelecidas para uso clínico como adjunto ao DEEG: 2a) detecçao automática de possíveis descargas epileptiformes ou crises epilépticas em registros prolongados, facilitando o trabalho subsequente do especialista; 2b) monitoraçao contínua do EEG na sala cirúrgica ou na UTI, visando reduzir complicaçoes. 3. Certas técnicas de QEEG sao consideradas possíveis opçoes práticas como uma adiçao ao DEG: 3a) análise topográfica e temporal de voltagens e dipolos de espículas na avaliaçao pré-cirúrgica de alguns tipos de epilepsia; 3b) análise de frequências em certos casos com doença cérebro-vascular, em quadros demenciais e em encefalopatias, principalmente quando outros testes, como os exames de imagem e o EEG convencional se mostrarem inconclusivos. 4. O QEEG permanece apenas como instrumento de pesquisa em doenças como síndrome pós-concussional, distúrbios do aprendizado, déficit de atençao, esquizofrenia, depressao, alcoolismo e dependência a drogas. O QEEG deve ser usado sempre em conjunto com o DEEG. Devido aos sérios riscos de erros de interpretaçao, é inaceitável o uso clínico do QEEG e de técnicas correlatas por médicos sem a adequada especializaçao em interpretaçao do EEG convencional e também nessas novas técnicas.