[Video-electroencephalography: a necessity]. / Vídeo-electroencefalografía: una necesidad.

The video-EEG is a common diagnostic tool nowadays. The technical achievements of the last decade have brought a simplification of the equipment required to obtain good quality recordings, with little more than a computer and a video camera being necessary. However, the medical and technical staff must be well trained to execute and interpret the study. It is very useful in the diagnosis of paroxysmal events, for the classification and characterization of epileptic seizures and to quantify epileptiform discharges. Due to the importance of a correct diagnosis to avoid mistreating many neurological patients, this tool should be accessible to clinicians. In spite of the advances of recent years, 20-30% of patients diagnosed with epilepsy are not really epileptic, a fact that it is excessive and unacceptable.

Alpha and beta changes in cortical oscillatory activity in a go/no go randomly-delayed-response choice reaction time paradigm.

OBJECTIVE: Predictable movements induce oscillatory changes over the contralateral motor cortex that begin before the movement, but their significance has not been fully established. We studied non-phase-locked changes in cortical oscillatory activity in a S1-centred double-stimulus go/no go paradigm with random interstimulus interval. METHODS: About 58 reference-free EEG channels were analyzed by means of Gabor transforms in a group of 10 healthy subjects. A 2000 Hz tone (S1go, 84% probability) indicated the subject to make a brisk wrist extension after a second 2000 Hz tone (S2go). The S1-S2 interval was either 1.5, 3 or 4.5 s. A 1000 Hz tone (S1 no go, 16% probability) indicated the subject not to move (and wait for another S1 tone). RESULTS: A frontal 15 Hz synchronization was observed after S1 in all conditions. No further significant changes were observed in the no go condition. A small pre-S2 alpha and beta desynchronization could be observed only in the 3 and 4.5s-interval go conditions, being larger in the latter. CONCLUSIONS: These results suggest that the predictability of the timing of a movement influences the appearance of the pre-movement oscillatory changes; not only motor planning (the 'go' decision) is necessary, but also an estimation of when to move. SIGNIFICANCE: Our findings provide new insight on the relationship between the decision-making process, movement, and cortical oscillatory activity.

[Monitoring of brain damage in patients with head injuries]. / Monitorización del daño cerebral en pacientes con traumatismo craneoencefálico.

INTRODUCTION: Early detection of impending cerebral ischemia in comatose patients is most important to avoid secondary insults to the injured brain. DEVELOPMENT: Whilst the computer tomography scan provides a static picture primarily concerned with details of structure, the electroencephalogram (EEG) is the objective source par excellence of information about brain function. The EEG represents the only biological activity suitable for continuous non-invasive monitoring of brain function. In this context, the cerebral function monitor (CFM) of Maynard and Prior (1969) provides a compressed array of amplitude variations and has benefited many critical patients. Among the invasive methods, direct monitoring of cerebral white matter oxygenation (tissular pressure of oxygen) is a promising new technique that has attracted considerable interest over the past four years. Recent studies on multimodal hemodynamic monitoring (intracranial pressure, cerebral perfusion pressure, PtiO2), place this latter technique as a primary basis for management decisions in the ICUs. We have studied four young injured patients, to compare early digital EEG recordings with tissular pressure of oxygen data. CONCLUSIONS: In general, there was agreement between EEG findings and tissular pressure of oxygen levels. The EEG helped with urgent data, though barbiturate therapy interfered in two cases.

[Subjective sleep quality and spectral analysis of electroencephalography during nocturnal sleep]. / Calidad subjetiva de sueño y análisis espectral del electroencefalograma de sueño nocturno.

INTRODUCTION: The relation between subjective sleep quality and the stages of polysomnography is unclear. Computerized sleep analysis provides a reliable tool for the study of sleep dynamics. OBJECTIVE: To study the relation between subjective sleep quality and spectral EEG parameters during nocturnal sleep. MATERIAL AND METHODS: Nocturnal sleep were recorded ambulatory in 26 subjects aged from 8 to 63. The following variables were extracted from EEG signal (Fz-Pz) quantified through the Fast Fourier Transformation (FFT): delta maximum, spectral peak, delta sleep time, efficiency and desynchronized sleep. A sleep diary was administered in the morning to assess the subjective sleep quality. Multiple regression and Anova were used for statistical analysis. RESULTS: Efficiency and delta maximum became significant predictors accounting for 54% of subjective sleep variance. The item 'how was your sleep?' was answered in a different way according to the delta maximum. CONCLUSIONS: Sleep depth, measured by spectral analysis, is an important predictor of the subjective sleep quality. The sleep classification in discrete stages ignores this feature.