Cerebral Edema Flashcards
What things can make the brain swell?
Edema, Extra CSF and tumors - It doesn’t take much increase in pressure to cause symptoms in patients
What are the two kinds of edema?
- Vasogenic
2. Cytotoxic
What is vasogenic cerebral edema?
It is caused by increased vascular permeability. Fluid shifts into intercellular spaces in brain. It can be localized (tumor, access) or generalized (hypoxia, insult to brain)
What is cytotoxic cerebral edema?
It is caused by cell membrane injury. It is seen in hypoxia or with metabolic damage to cells. It involves increased intracellular fluid.
What happens with vasogenic edema?
Something happens that damages or changes the permeability of the vessels and this causes fluid to leak out (more space between cells)
What happens in cytotoxic edema?
There is no damage to intracellular junctions, but there is something missing up the transport to from the cells (metabolic, etc.) Endothelial cells look swollen.
What can cause unilateral cerebral edema?
Brain tumor
How do you treat cytotoxic cerebral edema?
Can’t. Resistant to any known medical treatment.
How do you treat vasogenic cerebral edema?
- Vasogenic responds to steroids and osmotherapy (mannitol). It is usually not very responsive to diuretics or carbonic anhydrase inhibitors (agents that suppress cerebrospinal fluid production).
1. Steroids
2. Mannitol
How do steroids help vasogenic edema?
Steroids (dexamethasone) reduces water permeability of tight junctions.
How does mannitol help vasogenic edema?
- 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
How else do steroids function?
- They reduce WBC numbers and keep them away from inflammation sites.
- They are transcriptional regulators that turn proteins on and off.
What is Hydrocephalus?
It is the accumulation of excessive CSF within the ventricular system.
What happens if hydrocephalus happens in infancy vs. adulthood?
Infancy - sutures will enlarge and head enlarges
Adult - Ventricles expand, crushing brain and increasing cranial pressure
What are the 5 kinds of hydrocephalus?
- Communicating
- Non-communicating
- Ex vacuo
- Increased CSF production
- Normal pressure
What are two other ways to get a hydrocephalus?
- Blocked ventricle pathway (ex: tumor)
- Blocking CSF exit through arachnoid granulations - can occur after bad meningitis heals and the tissue thickens/blocks pathway
What is a noncommunicating hydrocephalus?
- Block in ventricular system
- Only part of the ventricular system is enlarged
- Causes:
- -Congenital malformation
- -Tumor
- -Abscess
- -Hematoma
What is a communicating hydrocephalus?
- Block in subarachnoid space
- Entire ventricular system is enlarged
- Causes:
- -Resolving meningitis
- -Subarachnoid hemorrhage
- -Dural sinus thrombosis (blood clot)
What is hydrocephalus Ex Vacuo?
- No block in ventricular system
- Ventricular system is dilated due to brain atrophy (with compensatory increase in CSF volume)
- Causes:
- -Alzheimer’s disease
- -Pick disease
- Brain itself shrinks
What is Hydrocephalus due to increased CSF?
- An uncommon type
- Cause: choroid plexus papilloma
What is normal pressure hydrocephalus?
-Elderly patient with
–Gait disturbance (slow, unsteady, wide-based)
–Unrinary incontinence
–Dementia
-Large ventricles, no cortical atrophy
-Maybe a form of communicating hydrocephalus
-Symptoms may be reversible!
Theory: Something happened that initially blocked the flow of CSF through the ventricles - then, as ventricles enlarged the pressure normalized on its own
-Often misdiagnosed as alzheimer’s disease
How do you treat hydrocephalus?
- Reduce fluid volume and pressure
- Get fluid out:
- -Surgery to remove tumor or blockage
- -Shunt to redirect CSF drainage
- Decrease CSF production using drugs:
- -Acetazolamide
- -Furosemide
What does Acetazolamide do?
It’s a carbonic anhydrase inhibitor. CA is a major enzyme at the blood-brain barrier that acts as a buffer in the blood.
What does furosemide do?
It blocks NKCC pump (Na, K, 2Cl pump) and this will produce the driving osmotic force for CSF production.
