Epileptiform EEG activity of the centromedian thalamic nuclei in children with intractable generalized seizures of the Lennox-Gastaut syndrome.

Centromedian thalamic nuclei (CM) epileptiform EEG activities were recorded in children with intractable generalized seizures of Lennox-Gastaut syndrome (LGS) through implanted recording-stimulating electrodes used for seizure control. Ictal CM epileptiform activities were consistently correlated to widespread surface cortical EEG activities and symptoms in all patients and all types of generalized seizures; i.e., fast spike discharges at CM correlated at onset of tonic and tonic-clonic generalized seizures; slow (1-2 Hz) spike-wave complex discharges at CM correlated for atypical absence seizures; slow polyspike-wave complex discharges correlated for myoclonic seizures; and spike bursts and suppression patterns correlated for combined tonic-atonic-myoclonic seizures. Ictal EEG activities occurred simultaneously at right and left CM and surface at onset of all seizure types, with the exception of myoclonic seizures where CM complete discharges and individual spike-wave complexes significantly lead those of the surface. Brief tonic-atonic spasms clinically undistinguishable from "real" epileptic seizures showed no EEG counterparts at CM and surface. Interictal CM spike-wave complete discharges and individual spike-wave complexes showed variable amplitude-temporal patterns. Amplitude emphasis on CM and frontopolar regions was observed in most of complete discharges, however, and phase shifts between CM and frontopolar regions were observed in individual spike-wave complexes.

Wakefulness-sleep modulation of EEG-EMG epileptiform activities: a quantitative study on a child with intractable epilepsia partialis continua.

Continuous all night recordings of epileptiform EEG activities from right frontal scalp and thalamic Centromedian regions and EMG activities from left deltoid muscular region were performed on a child with intractable epilepsia partialis continua, with depth stimulating-recording electrodes used for neuroaugmentive seizure control. In addition, "normal" and "mature" sleep indicators in the same child were simultaneously recorded according to the International Procedures. During wakefulness (W), type B seizures consisted of isolated, high amplitude, negative-positive EEG sharp waves recorded from the right Centromedian region (RCM sharp) correlated with isolated bursts of high amplitude EMG potentials recorded from the left deltoid muscle (LEMG jerks). Type C seizures consisted of clusters of repetitive RCM sharp and LEMG jerks, where individual EEG-EMG activities showed poor correlations. Number and amplitude of type B RCM sharp and LEMG jerks significantly decreased when patient directly shifted from W to slow wave sleep I and II (SWSI and II). Number and amplitude of RCM sharp increased while those of LEMG jerks decreased directly from SWS I and II to slow wave sleep III (SWS III); all forms of EEG-EMG epileptiform type B activities significantly decreased directly or indirectly from W and SWS to paradoxical sleep (PS). Scalp EEG spikes from right frontal and central regions showed almost parallel changes to those of RCM sharp, except during SWS II, when amplitude increased in the former and decreased in the later. Occurrence of type C seizures only decreased during PS and duration decreased directly from SWS I to II and indirectly from SWS I to SWS II and PS; and from W to SWS II and III and PS.

Effect of different factors on EEG spectral parameters.

We had previously observed that in groups of children with low socioeconomic and cultural level the EEG spectral parameters did not correlate with age due to the great variance in the distribution of such EEG parameters. In this paper we have made several statistical analyses in order to look for other factors that may explain the great variance observed. EEG during rest was recorded in 14 monopolar leads from 119 children. After FFT the following measures were calculated: absolute power, relative power, dominant frequency, coherence and left power/right power ratio for the delta, theta, alpha and beta bands in each derivation. For each measure, in each derivation, ANOVA analyses were performed taking age as covariable and sex, presence or absence of antecedents of risk factors and of learning disorders (LD) as independent variables. Age had its main effect on absolute power in the different bands and in the dominant frequency in the alpha band. Sex affected absolute and relative power in the alpha band. Risk factors per se had no effect. Presence of LD showed its main effect on absolute power. Many interactions between risk and LD and sex and LD were observed. Other analyses, such as MANCOVA, corroborated these results: significant differences between girls and boys, significant differences between children with and without LD and no differences between children with and without antecedents of risk factors.

EEG maturation on children with different economic and psychosocial characteristics.

It has been shown that EEG maturation can be described in terms of regression equations on age of broad band EEG frequency parameters. In the present paper six groups of children with different economic and psychosocial characteristics of three countries were studied. Regression equations on age of the EEG relative power (expressed in percentages of the total EEG activity) in the delta, theta, alpha and beta bands in 8 bipolar derivations were computed in each group of children and the slopes compared with those previously published by John et al. (1980). Those children who grew up with adequate nutritional, sanitary and cultural environmental conditions showed the same slopes as U.S. and Swedish children selected with strict criteria of normality. Children nourished in poor socioeconomic and sanitary environments and who frequently had pathological personal antecedents with risk factors associated with brain damage showed either a slow maturation of the EEG characterized by smaller slopes of theta relative power or a great variance of EEG parameters and no relation of these parameters to age.