In fact, arousal levels can vary normally from sleep to high anxiety levels in the course of a normal day s activity. These arousal levels are controlled by brain structures deep within the cerebral hemispheres and brain stem which send action potentials to the cerebral cortex where consciousness is centered. Such activity arouses one from sleep and controls the consciousness levels characteristic of daily activity. Injury to any part of the RAS can result in coma, the severity of which is determined by brain area involved. Some coma states resemble sleep without the characteristic REM eye movements characteristic of sleep cycling.
Some situations can involve motor impairments with sensory abilities intact.
With these clients, awareness of surroundings is good but they are unable to react to any stimulation. Consequently, care should be exercised as to conversational topics in casual conversation around comatose clients. Read text pages 1024-1029 before proceeding. Supratentorial coma results from damage to the white matter tracts leading from the tentorium of the midbrain to the cortex, Diffuse Axonal Injury, and can yield decorticate posturing. Depending upon the extent of white matter disruption, the prognosis would vary accordingly.