Cerebral Edema and Hydrocephalus (Pretty Much finished) Flashcards Preview

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Flashcards in Cerebral Edema and Hydrocephalus (Pretty Much finished) Deck (19)
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1
Q

List the two types of cerebral edema, and describe the causes of each.

A

Vasogenic
Cause: increased vascular permeability
Fluid shifts into intercellular spaces in brain
Localized or generalized

Cytotoxic
Cause: cell membrane injury
Increased intracellular fluid
Typically seen in hypoxia or with metabolic damage

2
Q

Describe the normal pathway of circulation of CSF

A

made in choroid plexus, flows through ventricles, spinal foramina, bathes brain, exits through ?
She spoke fairly fast, I didn’t catch it all. So this might not be completely accurate.

3
Q

Define hydrocephalus and list its causes and consequences.

A
Hydrocephalus: accumulation of excessive CSF within the ventricular system
If occurs during infancy, head enlarges
If after infancy, ventricles expand,  increased ICP
Five kinds: 
Communicating
Non-communicating
Ex vacuo
Increased CSF production
Normal pressure
4
Q

noncommunicating hydrocephalus

A
Block in ventricular system
Only part of the ventricular system is enlarged
Causes:
Congenital malformation
Neoplasms
Inflammatory processes (abscess)
Hemorrhage
5
Q

communicating hydrocephalus

A
Block in subarachnoid space
Entire ventricular system is enlarged
Causes:
Resolving meningitis
Subarachnoid hemorrhage
Dural sinus thrombosis
6
Q

hydrocephalus ex vacuo

A
No block in ventricular system
Ventricular system is dilated due to brain atrophy (with compensatory increase in CSF volume)
Causes:
Alzheimer disease
Pick disease
7
Q

List the causes of increased intracranial pressure,

A

Most often caused by mass effect (edema, tumor, hemorrhage)
Symptoms: headache, papilledema
If severe, may lead to herniation

Causes:
Unilateral space-occupying lesions
Tumor
Abscess
Hematoma
Diffuse lesions
Edema
Encephalitis
Subarachnoid hemorrhage
8
Q

Identify pharmacological agents that can be used to decrease intracranial pressure with emphasis on their mechanism of action at the cellular level and whole organism level.

A
  1. Cerebral Edema
  2. Steroids (dexamethasone): reduce water permeability of tight junctions
  3. Mannitol
  4. Osmotic diuretic
  5. Increase concentration of solute in blood and will suck fluid out of the brain. Water goes through aquaporins.
  6. 1-2g/kg
  7. Small sugar that doesn’t cross BBB
  8. Osmotic force pulls water across membranes
  9. Hydrocephalus
  10. Goal: reduce fluid volume and pressure. Get fluid out with surgery to remove tumor or blockage or shunt to redirect CSF drainage and decrease CSF production
  11. Acetazolamide (carbonic anhydrase inhibitor): blocks carbonic anhydrase which produces bicarb that goes into CSF and pulls water through. It also is important for getting Na and Cl in for the NKCC pump to use. CA is most important enzyme in CSF production.
  12. Furosemide: blocks NKCC pump so it decreases CSF by about 50%
9
Q

Utilize information about which pharmacological inhibitors suppress cerebrospinal fluid (CSF) formation to define critical physiological processes involved in the formation of CSF.

A

a

10
Q

Be capable of describing the mechanism of water transport through a cell when there is an osmotic gradient from one side of the cell to the other. The solution involves the concept of osmotic forces and the presence of water channels.

A

water goes from areas of low solute concentration to high solute concentrations if there are aquaporins to allows the passage of water through the membranes.

11
Q

if a carbonic anhydrase inhibitor suppresses CSF formation, does this provide insight into the role of carbonic anhydrase in CSF formation?
Go through this process for acetazolamide

A

a

12
Q

if a carbonic anhydrase inhibitor suppresses CSF formation, does this provide insight into the role of carbonic anhydrase in CSF formation?
Go through this process for furosemide

A

a

13
Q

Mannitol

A

Osmotic diuretic
1-2 g/kg, typically lasts 4-6 hours
Small sugar that doesn’t cross BBB
So number of particles in blood > number of particles in cells or CSF
Osmotic force pulls water across membranes

14
Q

Treatment of Cerebral Edema (vasogenic)

A

Vasogenic responds to both steroids and osmotherapy; typically not very responsive to diuretics or carbonic anhydrase inhibitors (agents that suppress cerebrospinal fluid production)

Steroids (dexamethasone): reduce water permeability of tight junctions

Mannitol:
Osmotic diuretic
1-2 g/kg, typically lasts 4-6 hours
Small sugar that doesn’t cross BBB
So number of particles in blood > number of particles in cells or CSF
Osmotic force pulls water across membranes

15
Q

Hydrocephalus Due to Increased CSF

A

An uncommon type of hydrocephalus

Cause: choroid plexus papilloma

16
Q

Normal Pressure Hydrocephalus

A

Elderly patient with:
Gait disturbance (slow, unsteady, wide-based)
Urinary incontinence
Dementia
Large ventricles, no cortical atrophy
Maybe a form of communicating hydrocephalus
Symptoms may be reversible!

17
Q

Treatment of Hydrocephalus

A
Goal: reduce fluid volume and pressure
Get fluid out
Surgery to remove tumor or blockage
Shunt to redirect CSF drainage
Decrease CSF production
Acetazolamide (carbonic anhydrase inhibitor)
Furosemide (Na, K 2 Cl pump inhibitor)
18
Q

Herniation

A
One part of brain gets pushed into another compartment
Symptoms/signs:
-Headache
-Papilledema
-Focal signs
-Vomiting
-Decreased level of consciousness
Often fatal
19
Q

increased intracranial pressure: describe the three main types of herniation that can result from it.

A

Subfalcine (Cingulate) Herniation

  • Expansion of one hemisphere displaces cingulate gyrus under the falx.
  • Can cause compression of branches of anterior cerebral artery
  • …leading to weakness of limbs, aphasia, etc.
Transtentorial (Uncinate) Herniation
Temporal lobe compressed against tentorium, affecting:
-Third cranial nerve 
        ~fixed, dilated pupil 
        ~impaired ocular movements
-Posterior cerebral artery 
       ~ischemia in primary visual cortex
-Brainstem
        ~Duret hemorrhages
         ~Impaired consciousness
-Contralateral cerebral peduncle
          ~Hemiparesis

Uncal Herniation:
?

Tonsillar Herniation

  • Displacement of the cerebellar tonsils through the foramen magnum
  • Compresses medulla, compromising vital respiratory and cardiac centers
  • Life-threatening!