We are said to be unconscious when we are unaware of sensations such as seeing, hearing, feeling, tasting, smelling . The reticular arousal system in the midbrain and subthalamic region awakens the cerebral cortex t the reception of sensations. If this formation is damaged or if the cortex is diffusely damaged we may lose consciousness. Sudden changes in the movement may cause temporary loss of consciousness by causing torsional strain on the mid-brain.
Space-occupying lesions like tumours and haemorrhages may press upon the mid-brain either directly or indirectly. The reticular arousal system is very sensitive to deficiencies of oxygen and also of glucose and these may therefore bring about unconsciousness. It is most important to realise that there are various levels of unconsciousness and that many patients who are apparently totally unconscious are, to some extent, aware of their…
