Module 10: Neursensory Disorders: Altered Cerebral Function and Increased
Intracranial Pressure (IICP)
Marnie Quick, RN, MSN, CNRN
Altered Cerebral Function
Normal brain physiology as it relates to altered cerebral function.
Consciousness is a dynamic state that can fluctuate between awareness of self
and environment to unawareness.
Etiology of altered cerebral function:
Lesions/injury to the RAS or cerebral cortex
Examples: brain lesions, cardiac (as an MI), respiratory, kidney,
diabetes, fluid and electrolyte imbalance, drugs that suppress the
CNS, and seizures.
Arousal/Cognition (Level of Consciousness) patho/assessment
Reticular formation (specifically the reticular activating system- RAS)
is a meshwork of gray cell bodies within the brainstem up to the
thalamus that controls wakefulness, arousal and alertness. Injury to
the RAS with an intact cerebral cortex results in difficulty with arousal
which in turn makes assessment of the cognitive function difficult.
Cerebral cortex is the outer layer of gray cell bodies of the brain
controls cognition; your thought processes. Widespread injury to the
cerebral cortex with an intact RAS, the individual has sleep-wake
cycles and may respond to stimuli, but not with understanding.
Begin assessment of altered cerebral function by observing the
individual’s behavior. Call their name, if no response then shake
individual- may be asleep.
Next assess verbal response: Note response to person, place, time,
and event questions
Normal- appropriately responds to each area
Abnormal- confusion in any one of the aspects, difficulty
with memory,(immediate recall, recent, or long term
memory) document accurately
If unable to assess verbal, then assess response to commands: Note
ability to follow simple (one-part) or complicated commands
Normal- able to follow commands in absence of paralysis
Abnormal- hard to arouse, slow, falls asleep easily, unable
to perform task
Lastly, if individual is unable to perform commands, then apply central
pain stimuli (sternal rub).