Neurophysiological studies in acute neurological diseases associated with impaired consciousness

Defining consciousness is a complex task for both the philosopher and the practicing neuroscientist. Consciousness is a global capacity that includes the conscious performance of elementary and intellectual tasks, the ability to think, plan, make judgments, recall, and the knowledge that all of these belong to our self. Consciousness and the structures behind it are empirically divided into two levels. These are awareness and wakefulness. Wakefulness means that the subject opens his eyes and becomes responsive to external or internal stimuli. Awareness involves the ability to use higher cortical functions, beyond the reception of stimuli, it is the ability to process and use internal and external stimuli. Consciousness is also the ability to think, remember, plan, to be self-aware. Our basic assumption is that damage to the structures necessary for awareness and wakefulness leads to a disturbance of consciousness.

Disorders of consciousness in subarachnoid haemorrhage (SAH) is a less frequently studied entity, presumably because of the difficulty of testing. An important predictor of outcome in SAH is the presence or severity of the impairment of consciousness in the acute stage. EEG is an ideal technique to study large-scale neural networks with high temporal resolution. Compared to other available techniques, it is much cheaper, has better temporal resolution and is easier to use. It has the disadvantage of a lower spatial resolution, but this can be compensated by increasing the number of electrodes (so-called high-density EEG). 64 or more channels are available in a limited number of studies in the field of brain disorders. The aim of our study is to investigate the causes of SAH-related disorders of consciousness using high density EEG and to compare different treatment strategies using EEG markers.