[Functional connectivity derived from an electroencephalogram during non-REM sleep in autism spectrum disorders]. / Conectividad funcional derivada del electroencefalograma durante el sueño no REM en los trastornos del espectro autista.

AIM: To know the differences in the patterns of functional connectivity, the topological characteristics of the network and the relationship between these latter and the interictal epileptiform anomalies in children with primary and secondary autism spectrum disorder (ASD). PATIENTS AND METHODS: A retrospective study was conducted with 27 children aged between 3 and 13 years diagnosed with ASD. Subjects were submitted to an electroencephalogram in a functional state of spontaneous sleep. Functional connectivity and the properties of the network were analysed using data obtained from the electroencephalogram during the N2 stage of non-REM sleep. The frequency of discharge of the interictal epileptiform activity (FDIEA) was determined and was correlated with the topological properties of the network. RESULTS: Synchronisation was diminished in patients with secondary ASD for the alpha frequency and increased for the theta and delta frequency compared with patients with primary ASD. Local alpha efficiency was higher in patients who presented interictal epileptiform activity. Additionally, in patients with secondary ASD there was a statistically significant positive and negative correlation between FDIEA and the topological properties of the network. CONCLUSIONS: Patients with secondary ASD display patterns of functional connectivity that are weaker for the alpha frequency and stronger for theta and delta than patients with primary ASD. In patients with secondary ASD, the interictal epileptiform activity is related to local and global connectivity of the network for the alpha and beta bands during non-REM sleep.

TITLE: Conectividad funcional derivada del electroencefalograma durante el sueño no REM en los trastornos del espectro autista.Objetivo. Conocer las diferencias en los patrones de conectividad funcional, las caracteristicas topologicas de la red y la relacion de estas con las anomalias epileptiformes interictales en niños con trastorno del espectro autista (TEA) primario y secundario. Pacientes y metodos. Se realizo un estudio retrospectivo con 27 niños de 3-13 años diagnosticados con TEA, a los que se les realizo un electroencefalograma en estado funcional de sueño espontaneo. Se analizo la conectividad funcional y las propiedades de la red a partir de los datos obtenidos del electroencefalograma durante la etapa N2 del sueño no REM. Se determino la frecuencia de descarga de la actividad epileptiforme interictal (FDAEI) y se correlaciono con las propiedades topologicas de la red. Resultados. Los pacientes con TEA secundario tenian una disminucion de la sincronizacion para la frecuencia alfa y un incremento para la frecuencia theta y delta en comparacion con los pacientes con TEA primario. La eficiencia local alfa fue mayor en los pacientes que presentaban actividad epileptiforme interictal. Ademas, en los pacientes con TEA secundario, existia una correlacion positiva y negativa estadisticamente significativa entre la FDAEI y las propiedades topologicas de red. Conclusiones. Los pacientes con TEA secundario muestran patrones de conectividad funcional mas debiles para la frecuencia alfa y mas fuerte para la theta y delta que los pacientes con TEA primario. En pacientes con TEA secundario, la actividad epileptiforme interictal se relaciona con la conectividad local y global de la red para las bandas de frecuencia alfa y beta durante el sueño no REM.

[Effects of lobectomy on the auditory mid-latency response in temporal lobe epileptic patients]. / Efectos de la lobectomía sobre el potencial evocado auditivo de latencia media en pacientes con epilepsia del lóbulo temporal.

AIM: Auditory mid-latency response (MLR) has been studied in temporal lobe epileptic patients in order to evaluate the relationship between the different components of this evoked response and their probable generators in the most rostral part of auditory pathway. PATIENTS AND METHODS: MLR was studied in eight patients with temporal lobe epilepsy before lobectomy, and 1, 6 and 12 months after the surgical treatment, and eight healthy subjects matched for age and gender. Recording electrodes were placed in Cz, T3 and T4 according to the international 10-20 system. Comparisons were carried out in terms of peak to peak amplitude, latency and interpeak intervals of the main components (Mann-Whitney U test, Wilcoxon test). RESULTS: Epileptic patients showed statistically significant prolonged latency of all components, and increased Pa-Pb interpeak interval duration respect to control group. No significant variations were found in the amplitude of the studied components. There were no differences between left and right lobotomized patients. However, a marked tendency to the shortening of latency was observed in the left group after the surgical treatment. CONCLUSIONS: The differences between the pre-surgical records of patients and controls reflect an impaired activity in the generating areas for MLR components. There appears to be a trend to a different behaviour after right or left lobectomy, probably related to the extension of the removed tissue.

[Mid-latency auditory evoked potential]. / Potencial evocado auditivo de media latencia.

AIMS: Given the diversity of criteria regarding the use of the midlatency auditory evoked potential (MLAEP) for diagnostic purposes, we carry out a review of the subject and highlight areas such as the generators of fundamental components, the conditions in which responses are obtained, factors that can modify results and the clinical uses that have been reported. DEVELOPMENT: There seems to be a strong tendency towards considering areas of the primary and secondary auditory cortex as generators of the response, with the subcortical structures playing a moderating role. Factors such as age, the method of stimulation used and the monitoring conditions can all exert an influence on the characteristics of this evoked response and modify its capacity for detection and repetition. Clinical uses of this potential range from the detection of the hearing threshold, monitoring the depth of anaesthesia, the functional evaluation of cochlear implants, and the diagnosis of neurological disorders, among others. CONCLUSIONS: MLAEP is a technique that is widely used in the study of the most rostral segments of the auditory pathway and this information complements that provided by short latency responses and increases the diagnostic sensitivity of auditory evoked potentials.

[Giant evoked potentials]. / Potenciales evocados gigantes.

INTRODUCTION: There are many, diverse nosological entities with the common factor of the genesis of cortical evoked potentials of great amplitude, commonly known as giant evoked potentials. In most cases they are conditions with the common clinical condition of myoclonic of cortical origin, such as progressive myoclonic epilepsy, generalized idiopathic epilepsy, myoclonias of toxic, infectious or postanoxic origin. Giant potentials have been shown both in studies of focal hemisphere lesions and in some cases of patients with corticobasal degeneration. OBJECTIVE: The aim of this paper was to show, by presenting interesting cases, some of the conditions mentioned and to review some concepts concerning the mechanisms which may be involved in the production of these electrophysiological responses. PATIENTS AND METHODS: We studied 6 patients aged between 2 and 22 years, in whom multimodal evoked potentials, electroencephalograms and imaging studies had been done. RESULTS: Giant somatosensory potentials were shown in the patients with obvious myoclonia. Visual potentials of great amplitude were common to the other patients presented, with or without myoclonia. CONCLUSION: Giant evoked potentials respond to a state of cortical hyperexcitability which may have various causes.

[Actual status of multiple sclerosis in Cuba. National cooperative group for the clinical trial "Recombinant interferon alpha-2b in multiple sclerosis"]. / Estado actual de la esclerosis múltiple en Cuba. Grupo Cooperativo Nacional para el Ensayo Clínico 'Interferón alfa-2b recombinante en la esclerosis múltiple'.

INTRODUCTION: Multiple sclerosis (MS) has been considered to be an uncommon disorder in Cuba. In recent years many Cuban investigators have worked hard studying MS in Cuba. DEVELOPMENT: We review the history, epidemiology, clinical characteristics, complementary investigations and clinical trials of recent studies published in national and international journals on the most important investigations done on MS in Cuba. There is an outstanding placebo-controlled, double blind, multicentric randomised clinical trial using recombinant alpha 2b-IFN in the relapsing-remitting clinical form in which the results obtained in the first 30 patients who completed 2 years treatment show a statistically significant reduction in the frequency of relapses and the number of patients free of relapses in patients who received alpha-IFN as compared with those given placebo treatment. CONCLUSIONS: There has been an increase in the number of studies made on MS in Cuba in the past two years. Numerous clinical, neuroepidemiological, neurophysiological, biochemical, immunological, imaging and neuropsychological investigations and clinical trials indicate a marked increase in understanding of MS. The results of all these studies indicated the need for the creation of a National Reference Centre for Patients with Multiple Sclerosis, due to the complexity of this type of patients and the need to offer improved medical attention from a specialist team and to integrate the investigations in Cuba and internationally so as to reach the level of more developed countries.

[Effects of monaural and binaural stimulation on middle latency auditory evoked responses]. / Efectos de la estimulación monoaural y binaural sobre la respuesta evocada auditiva de latencia media.

INTRODUCTION: Middle latency evoked potentials include a series of evoked responses which encompass/include myogenic potentials (which translate the existence of sonomotor reflexes), and others which are clearly of neurogenic origin. The latter are the most useful from the clinical point of view. OBJECTIVE: To evaluate the effects of monoaural (MA) and binaural (BA) stimulation on middle latency auditory evoked potentials. PATIENTS AND METHODS: We studied 15 healthy people, aged between 18 and 52 years, in whom Cz recording electrodes had been fitted to both short-circuited external ears with Fpz as earth. The stimuli used were alternate clicks of condensation and rarefication of 90 dBHL, first BA and them MA. The auditory evoked response from the brain stem was also recorded. RESULTS: We found more stability of most of the components evaluated during biauricular stimulation. All subjects had Pa waves and 93% had Pb waves. Statistically significant differences were only found for the amplitude of Po and Pa (BA against RE) (Wilcoxon test, p < 0.05). CONCLUSION: The use of BA stimulation to obtain middle latency evoked potentials is more useful for study of the more rostral parts of the auditory path, since its components are more stable.