Stroke 1 Flashcards
Brain is __% of the body weight
Brain uses __% of cardiac output
Brain uses __% of total body oxygen
2% of body weight
Uses 15% of CO
Uses 20% of total body oxygen
What arteries supply the anterior and posterior portions of the brain?
Anterior 3/5th supplied by internal carotid.
Posterior 2/5 (cerebellum, brainstem) supplied by the vertebral arteries that join to form the basilar arteries.
Why are neurons primarily aerobic?
They need O2 and glucose.
They don’t store glucose- they require continuous supply of glucose and O2.
Few minutes of ischemia= irreversible injury.
Subdural vs epidural hematoma
Subdural: Bleeding into the space between the dura mater and brain itself
Epidural: Bleeding into the space between the dura mater and skull.
What happens in the brain if oxygen and glucose levels are low?
Oxidative stress.
Ischemia causes mitochondrial disfunction.
Excess glutamate causes cell death
Excess intracellular calcium causes cell death.
ROS causes mitochondrial disfunction.
Transient Ischemic Attack
A brief period of inadequate cerebral perfusion. Sudden focal loss of neurologic function.
*Rapid onset and resolution. Less than 5 mins of duration. Usually followed by full recovery within 24 hours.
Transient loss of blood flow, but no permanent damage
Difference between TIA and mini stroke
TIA: Transient loss of blood flow, but no permanent damage
Mini stroke: small strokes with permanent defects
*TIA possible causes
*Intermittent vessel obstruction- clots/thromboses, plaques
temporary vasospasm due to drugs, stress, smoking, or migraines.
*___% of patients who have TIA will have a full blown stroke if left untreated within 1 year
35%
TIA symptoms
- Paresis in arm, legs, or face.
- *Diplopia
- *Transient vision loss, amaurosis fugax
Vertigo, loss of speech, loss of understanding, loss of balance
TIA distinguishing symptoms of non-TIA events
*Speed of onset. Fast, not slow! lightheaded Tightness in the chest Stomach upset History of similar epodes where TIA was ruled out
TIA workup
Main:
Carotid auscultation, carotid ultrasound, echocardiogram.
Additional: CTA, MRA, lab work, ECG
Stroke defintion
Disturbance of blood supply causing loss of brain function. More severe than TIA by definition.
Permanent disturbance/damage to neurons.
Stroke is #__ cause of death in US
5. #6 world wide
High risk population for stroke
Older adults
African americans, american indians, alaska natives
Low level of education
Southeastern US
Stroke risk factors
*****HTN
*Diabetes
Obesity
Heart disease
Atherosclerosis
High cholesterol
Smoking
Previous stroke or TIA
2 types of stroke
Ischemic, Hemorrhagic
Ischemic stroke is what percentage of all strokes and what is the mortality
80-85% of all strokes
40% mortality
Hemorrhagic stroke is what percentage of all strokes and what is the mortality
15-20% of all strokes
Mortality is 80%
What is the most common cerebral artery affected by CVA? What percentage of strokes?
Middle Cerebral artery
50-75% of strokes
8.5% of strokes are due to posterior cerebral artery
Ischemic stroke is primarily due to blood vessel occlusion. What 4 things causes this?
Thrombotic (35%)
Embolic (30%)
Lacunar (20%)
Dissection (5% due to carotid and vertebral)
Ischemic stroke is due to which two things?
Primary: Blood vessel occlusion.
Secondary: Systemic hypofusion. Pump failure and hypovolemia. (hypovolemia can lead to shock)
Most at risk areas for ischemic stroke
Watershed areas. These are most distal areas supplied by arteries. Minimal overlap of blood supply. Location is between major arteries- border zones.
Embolic stroke due to which main two things?
Artery/vein thrombosis
Plaque fragments from carotid arteries
What causes a hemorrhagic stroke?
Intracranial artery rupture. due to hypoxic or hydraulic damage.
Common causes of hemorrhagic stroke
HTN.!!!!!!!!!!!!!!!
Symptoms of hemorrhagic stroke
Sudden onset, severe HA.
2 main locations of hemorrhagic stroke
Extra axial- outside brain tissue.
Intra axial- inside brain tissue.
3 locations for extra axial hemorrhagic stroke
- Epidural due to middle meningeal artery (80%)
- Subdural due to acceleration/deceleration injury.
- Subarachnoid due to saccular aneurysm rupture or trauma.
Intracranial cerebral hemorrhage due to
Rupture and hemorrhage into the brain- hypoxic or hydraulic injury.
Associations: HTN
Example of arteriovenous malformation
Wyburn-ason Syndrome.
Stroke in adults less than 65 years old is __% of all strokes
25%
More serious risk factors for stroke in young adults
Trauma and migraines
Clotting disorders, vascular abnormalities, cardiac embolism.
X ray
- What does it image?
- Pros?
- Cons?
High energy EMR to image bone.
- Fractures of bony defects
- Sacro-iliac junction
- Chest
Pros: Fast and cheap
Cons: poorer resolution compared to CT. Radiation exposure.
Angiography
-Cons
X ray + contrast combo
Pinpoints exact location of blockage/bleeding in brain
Cons: Increased thrombosis risk, invasive, radiation exposure.
CT
- Images what and how?
- Injection of what
Uses many X rays + computer to view bones/orbit, intracranial bleeds, infractions.
Requires injection of iodine dye.
When do you need an urgent head CT?
Identifies hemorrhagic vs ischemic stroke very quickly.
MRI
-Images what and how?
Magnetic field + computer to view soft tissue details, intracranial bleeds, and infarctions.
No radiation!
PET scan
-images what?
Detects functional rather than structural abnormalities.
Used for epilepsy or tumor biopsy.
How can you use MRi to diagnose or detect strokes?
Identifies and further localizes the site of the stroke and find the source.
pro: Very safe, no radiation. OK on pregnancy.
Con: $$$, poor bone detail.
Stroke suspects in ER what do you do?
Emergent/STAT CT scan to see if it is ischemic or hemorrhagic.
THEN tailor treatment pending results from CT.
Ischemic Stroke Tx
Tissue plasminogen activator: intravenous. Dissolves clot. May cause hemorrhaging so it is contraindicated in hemorrhagic strokes.
This must be administered within 3 hours of stroke onset and it must be ischemic.
Further tx: Monitor and control risk factors.
Tissue plasminogen activator
intravenous. Dissolves clot. May cause hemorrhaging so it is contraindicated in hemorrhagic strokes.
This must be administered within 3 hours of stroke onset and it must be ischemic.
Hemorrhagic stroke Tx
Monitor closely
Surgery
*Control blood pressure
Discontinue anticoagulant therapy.
Main risk factor for stroke
HTN
Stroke rule of 3rds
1/3 recover with no or minimal disability.
1/3 Recover with residual disability
1/3 die
Stroke prognosis scale
0-3 months
3-6 months
6-12 months
12+ months
0-3: largest change of recovery
3-6: Some recovery possible
6-12: Unlikely recovery
12+ months: permanent
