NEUROSURGICAL CONSIDERATIONS ON THE BRAIN MECHANISMS OF CONSCIOUSNESS.

Abstract

The different aspects of conscious and unconscious states in humans may be studied particularly in patients with head injuries, cerebro-vascular accidents, epilepsy and intracranial tumours. The cause of the sudden loss of consciousness in concussion of the brain is still a matter of discussion, and various opinions are presented. Among the cerebro-vascular diseases the rupture of saccular aneurysms on the anterior part of the circle of Willis is often accompanied by severe disturbances of consciousness. The importance of the posterior mesial parts of the frontal lobes in the maintenance of functions of consciousness is stressed. Structures in the vicinity of the third ventricle and the aqueduct of Sylvius also play an essential role in this respect. The reticular formation of the brain stem may be severely affected by tumour infiltrations without serious impairment of consciousness. A massive reduction of the amount of nervous tissue in regions considered significant for consciousness is thus not sufficient to abolish the conscious state. The time factor ofDott is a necessary component for a complete disruption of function.