Neuro 2 Flashcards
anoxic/hypoxic brain injury
lack of oxygen to brain causing stroke like damage
- anoxic = complete lack of oxygen to the brain
(cells die after ~4 min of oxygen deprivation) - hypoxic = restriction of oxygen to the brain causes gradual cell death Eg: cardiac arrest, hypotension
what does longer down time in anoxic/hypoxic brain injury indicate?
more significant damage and increased risk of permanent damage
anoxic/hypoxic brain injury: where are changes seen?
on CT scan 72 hrs post
event, may need MRI to neuroprognosticate
what is a stroke?
sudden loss of brain function lasting longer than 24 hours caused by:
- interruption of blood flow to the brain (ischemic stroke)
- rupture of blood vessels in the brain (hemorrhagic stroke)
what happens to neurons in a stroke? what are the effects?
- neurons affected by interrupted blood flow can infarct or die
- effects depend on what area of the brain was injured and how much damage occurred
ischemic penumbra
zone of ischemic tissue surrounding an infarcted area (early reperfusion can salvage this area)
what type of stroke is more common?
ischemic (87%)
hemorrhagic (13%)
what are the categories of ischemic strokes?
thrombotic (80%) and embolic (20%)
what are the categories of hemorrhagic stroke?
intracerebral (10%) and subarachnoid (3%)
what is the most commonly involved vessel for neurovascular syndrome?
middle cerebral artery
cerebral blood supply: circle of willis (what is it, where does blood come from, circulation)
- circle of arteries that supply blood to brain
- receives blood from vertebral and carotid arteries
- connects anterior and posterior circulation
- allows for collateral circulation and constant oxygen availability
what is a common aneurysm site and why?
circle of willis d/t high flow in small vessels
what happens if an artery becomes occluded?
circle of willis can still support cerebral blood flow
stroke signs and symptoms
- headache
- blurred vision
- dizziness
- sudden confusion
- difficulty speaking
- facial droop
- unilateral weakness
what is the more common hemorrhagic stroke?
subarachnoid
hemorrhagic stroke
blood seeps out of a ruptured vessel into surrounding tissue
subarachnoid hemorrhage
- worst headache of my life
- cause = trauma, structural malformations
- aneurysm (85%) - weak area of artery, bulges outward and fills with blood
- ArterioVenous Malformation (AVM) (6%) - tangle of very thin-walled veins and arteries
what is used to grade a subarachnoid hemorrhage?
- hunt and hess scale
- determine how to triage and treat; graded by severity of symptoms and gives survival rate
- 5 grades of SAH; grade 5 is worst, survival rate is 10%
subarachnoid hemorrhage: diagnosis
diagnosis: symptoms, non-contrast head CT and cerebral angiogram
*CT done in first 24 hours = 90-100% sensitivity, after this it decreases in sensitivity as blood diluted by flow of CSF
subarachnoid hemorrhage: tx
- close monitoring – vitals, neuro assessment
- craniotomy – evacuation of blood
- surgical repair of aneurysm (clip or coil)
- EVD
BP goals
- Prior to repair – normal
- After repair – higher (sBP 150-180 & MAP >80 to maintain CPP)
what is the most lethal complication in an unsecured aneursym (less common with AVM)?
rebleeding
when does the majority of rebleeding occur?
during the first 6hrs after the first bleed
what can you do to prevent rebleed?
- Monitor for change in neuro exam
- Elevate HOB and maintain neutral alignment
- Decrease stimulus to ↓ BP and demand
- Normal BP goals, set SBP limit
- Anticipate fever due to blood in SA space –> increased ICP –> damaged function of hypothalamus –> neurogenic fever (high temp, anti-pyretic resistant, no sweating)
complications post aneurysm repair
1) increased ICP
- Seizures: irritation by blood in SA space→ seizures → increased demand → increased ICP
- Hydrocephalus → blocking CSF outflow
2) vasospasm
- Reversible narrowing of cerebral arteries
- Etiology largely unknown
- Typically occurs 3-10 days after repair and causes decreased blood flow *presents like a stroke
