Categories of causes of unconsciousness:
Structural causes;
Metabolic causes.
fractional loss of consciousness - pts ± preserved awareness of most stimuli, but having suffered the loss of a critical population of neurons (e.g., for recognizing language symbol content, differences between colors or faces, or the presence of the left side of space) → unconscious to associated class of stimuli.
A reduced level of consciousness = global ↓ in the level of behavioral responsiveness; due to widespread cortical impairment, injury to a specific set of brainstem and diencephalic pathways that regulate the overall level of cortical function; abnormal activity of RAS; Pathologic alteration between wakefulness and sleep systems;
Terms Used to Describe Disorders of Consciousness: