levels of consciousness
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Related to levels of consciousness: States of consciousness
Consciousness depends upon close interaction between the intact cerebral hemispheres and the central gray matter of the upper brainstem. Although the hemispheres contribute most of the specific components of consciousness (memory, intellect, and learned responses to stimuli), there must be arousal or activation of the cerebral cells before they can function. For this reason, it is suggested that a detailed description of the patient's response to specific auditory, visual, and tactile stimuli will be more meaningful to those concerned with neurologic assessment than would the use of such terms as alert, drowsy, stuporous, semiconscious, or other equally subjective labels. Standardized systems, such as the glasgow coma scale, aid in objective and less ambiguous evaluation of levels of consciousness.
Examples of the kinds of stimuli that may be used to determine a patient's responsiveness as a measure of consciousness include calling him by name, producing a sharp noise, giving simple commands, gentle shaking, pinching the biceps, and application of a blood pressure cuff. Responses to stimuli should be reported in specific terms relative to how the patient responded, whether the response was appropriate, and what occurred immediately after the response.
levels of consciousness
Alert wakefulness: The patient perceives the environment clearly and responds quickly and appropriately to visual, auditory, and other sensory stimuli.
Drowsiness: The patient does not perceive the environment fully and responds to stimuli appropriately but slowly or with delay. He or she may be roused by verbal stimuli but may ignore some of them. The patient is capable of verbal response unless aphasia, aphonia, or anarthria is present. Lethargy and obtundation also describe the drowsy state.
Stupor: The patient is aroused by intense stimuli only. Loud noise may elicit a nonspecific reaction. Motor response and reflex reactions are usually preserved unless the patient is paralyzed.
Coma: The patient does not perceive the environment and intense stimuli produce a rudimentary response if any. The presence of reflex reactions depends on the location of the lesion(s) in the nervous system.