Class 14 - Alterations in Neuro - Intracranial Pressure

Question 1

Normal A&P - General Principles

Answer 1

• Brain function is site specific
• The brain has lymphatic channels
• The brain is encased in bone and has little rooms to swell or move
• Neurons are sensitive to glucose deprivation
• Large molecules cannot diffuse easily into the brain from the blood. This is bad for when we want antibiotics/cancer drugs to enter the brain
• Cerebral blood vessels are frequently affected by atherosclerosis. Circle of Willis: interconnections at base of brain. Relatively few interconnections elsewhere

Question 2

Increased Intracranial Pressure

Answer 2

• Dependent on the relationship between the brain tissue, cerebrospinal fluid and blood.
• Normal pressure is 5-15 mmHg
• Monro-Kellie Hypothesis. An increase in volume fro one component must be offset by a decrease in others. May decrease blood flow

Increased pressure occurs when

• Compensatory mechanisms are no longer effective
• Increased intracranial pressure = cerebral perfusion
• Further injury can occur once we can no longer compensate
• Blood flow to the brain could stop
• End result of increased intracranial pressure is brain tissue displacing
• Herniation: brain will be squished down the verebrum magnum

Manifestations
- Altered level of consciousness (LOC) **Earliest indicator 
- Pupillary alterations
- Changes in vital signs
- Water imbalances (ADH)
- Seizures
- Headaches
- Vomiting
Impaired brain stem and cranial nerve function

Question 3

Level of Consciousness

Answer 3

Most critical index of nervous system function

• Arousal
• Awareness

Assessed by using the Glasgow Coma Scale

• Highest score is 15
• Lowest score is 3 - coma

Terms used in describing altered LOC

• Confusion
• Disorientation
• Lethargy
• Obtundation (dull or less sharp)
• Stupor
• Coma

Question 4

Pupillary Abnormalities

Answer 4

Initially changes on the same side of the brain as injury
- Ipsilateral
Alteration in size (pinpoint, larger, dilated)
Alteration in response (sluggish, fixed)

Question 5

Changes in Vital Signs due to ICP

Answer 5

• Temperature. Pressure is put on hypothalamus
• Respirations. Pons and medulla
• Heart rate. Medulla
• Blood rate. Medulla

Cushings Triad

• Indicative of impending herniation
• Bradycardia*
• Irregular respirations*
• Widening pulse pressure (systolic - diastolic), gets bigger*
• Later findings
• Don’t wait for cushings triad