Cerebral Edema and Hydrocephalus (Pretty Much finished) Flashcards
List the two types of cerebral edema, and describe the causes of each. Describe the normal pathway of circulation of CSF. Define hydrocephalus and list its causes and consequences. Define the terms noncommunicating hydrocephalus, communicating hydrocephalus, and hydrocephalus ex vacuo. List the causes of increased intracranial pressure, and describe the three main types of herniation that can result from it. Identify pharmacological agents that can be used to decrease intracrania
List the two types of cerebral edema, and describe the causes of each.
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
Describe the normal pathway of circulation of CSF
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.
Define hydrocephalus and list its causes and consequences.
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
noncommunicating hydrocephalus
Block in ventricular system Only part of the ventricular system is enlarged Causes: Congenital malformation Neoplasms Inflammatory processes (abscess) Hemorrhage
communicating hydrocephalus
Block in subarachnoid space Entire ventricular system is enlarged Causes: Resolving meningitis Subarachnoid hemorrhage Dural sinus thrombosis
hydrocephalus ex vacuo
No block in ventricular system Ventricular system is dilated due to brain atrophy (with compensatory increase in CSF volume) Causes: Alzheimer disease Pick disease
List the causes of increased intracranial pressure,
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
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.
- Cerebral Edema
- Steroids (dexamethasone): reduce water permeability of tight junctions
- Mannitol
- Osmotic diuretic
- Increase concentration of solute in blood and will suck fluid out of the brain. Water goes through aquaporins.
- 1-2g/kg
- Small sugar that doesn’t cross BBB
- Osmotic force pulls water across membranes
- Hydrocephalus
- 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
- 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.
- Furosemide: blocks NKCC pump so it decreases CSF by about 50%
Utilize information about which pharmacological inhibitors suppress cerebrospinal fluid (CSF) formation to define critical physiological processes involved in the formation of CSF.
a
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.
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.
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
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
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
Treatment of Cerebral Edema (vasogenic)
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
Hydrocephalus Due to Increased CSF
An uncommon type of hydrocephalus
Cause: choroid plexus papilloma
