Edema, ICP, Herniation

Question 1

cytotoxic edema

Answer 1

• intracellular edema
• increase in cell volume from a hypoxic/ischemic event = inhibits active transport pumps = influx of Na and water = cell swelling

Question 2

extracellular edema

Answer 2

• accumulated CSF (from obstruction or stenosis)

- can happen from infection/inflammation = scar tissue at arachnoid villi = no reabsorption of CSF (like in meningitis)

Question 3

most common cause of congenital hydrocephalus?

Answer 3

• stenosis of aqueduct of Sylvius

Question 4

protein concentration in CSF v. plasma

Answer 4

• protein low in CSF compared to plasma
• when there is acute inflammation: proteins move into CSF - bring in water w/ them - extracellular CSF edema - increase in ICP = headaches and possible herniation

Question 5

mechanism/cycle of ICP

Answer 5

• CSF increases enough to compress veins = decrease in cerebral blood flow = cells become hypoxic = increased permeability of BBB = proteins move into CSF = bring water in w/ them = increase in ICP = further edema
• cycle perpetuates until pressure goes up high enough, causes infarct and you die
• if your CO2 goes up = vasodilation = blood flow back to normal = autoregulation

Question 6

what can you do to save a pt w/ inc. ICP and you can’t drill burr holes?

Answer 6

• hyperventilate pt = vasodilation
• then give hypertonic mannitol = sucks fluid from interstitium = decreases edema and increases caliber of blood vessels; causes BP to go up = more volume but that will lead to more edema
• So you give a powerful diuretic after the mannitol so the extra fluid goes into urine instead of back to the brain

Question 7

Cushing’s reflex

Answer 7

• increase in BP w/ decrease in HR

Question 8

most common herniaton?

Answer 8

• subfalcarine

- displacement of brain beneath falx cerebri b/c of increased ICP

Question 9

uncal herniation

Answer 9

• aka transtentorial herniation
• uncus compressed against tentorium cerebelli
• CNIII compression = affected eye down and out and pupillary dilation

Question 10

tonsilar herniation

Answer 10

• tonsil herniates through foramen magnum

- compression on brainstem = life threatening b/c of cardio and resp control centers getting compressed