Lecture: CVA intro Flashcards
Acute signs and symptoms
F- face drooping
A- arm weakness, can be leg too, usually unilateral
S-slurred speech and confusion, dizziness, bad gait
T- time counts- 911, faster the hospital comes, the better
Loss of blood flow to the brain leads to
↓ O2 and metabolites (glucose), resulting in neuronal dysfunction and cell death
Stores of O2 and glucose are used within minutes triggering the onset of neurologic deficits
Without the blood flow, there is also a toxic build-up of metabolic waste, resulting in additional damage
Secondary damage: Ischemic cascade
Occurs in…
How it leads to tissue death and when does it happen
• Occurs in the aftermath of the acute infarct
• Damaged or dying neurons release excessive amounts of glutamate
• Cells that normally take up this neuro-transmitter are compromised, causing…
-Disturbance of energy metabolism (inability to produce ATP)
- Facilitates entry of Ca2+ into cells
- Activates catabolic enzymes that further degrade the neural structures
An ischemic cascade leads to cell death in how many hours
The ischemic cascade leads to an area of apoptosis & tissue death beyond the infarction, usually within 3-4 hrs
Ischemic stroke 3 mechanisms of injury
- Local hypoxia
- Local hypoglycemia
- Build-up of toxic metabolic waste
Penumbra, what happens in it
collateral arteries anatomizing with branches of the occluded vascular tree for several hours
The ischemic CVA is rarely fatal. . . BUT
Cerebral edema is a potentially fatal sequela!
• ↓ vascular perfusion into the brain à osmolality ↑ during ischemia
-> Influx of fluid into the brain to restore normal osmotic pressure ->EDEMA!
• Begins minutes after occlusion & peaks in 3-4 days
• Can cause ↑↑ ICP resulting in severe 2 ̊ structural damage (i.e.Brainstem herniation)
• Most frequent cause of death, esp. seen in large infarcts involving the MCA & ICA
Thrombotic CVA:
Most common in ___ arteries
Most common in • Internal carotid artery - vertebral artery - Basilar artery - middle cerebral artery
Thrombotic CVA:
Manifests as.. evolves over…
Often occurs during..
Often manifests as a focal neurologic deficit that evolves over several hours or days (symptoms occur over days)
• Often occurs during sleep
Thrombotic CVA:
Caused by…
• Is highly associated with atherosclerotic vessel disease, DM and HTN
Thrombotic CVA:
Poorer prognosis compared to…
• Poorer prognosis compared to embolic CVAs
Most common origins of an emboli
A-fib- blood flow is stagnant in L atrium
MI- damaged myocardium
Fat, bullets, catheter tips, sponge pieces
Onset of Embolic CVA
Onset is sudden with focal deficits occurring within seconds to minutes
• More frequently associated with TIA
• Associated with seizures, precipitating headache, transient confusion
and/or loss of consciousness (LOC)
• Emboli tend to terminally lodge in smaller vessels, producing more
discrete, focal deficits
Systemic cause of Ischemic CVA
- Low systemic perfusion secondary to cardiac failure or significant blood loss
- Widespread hypo-perfusion & ischemia leads to anoxic brain injury
- Neurological deficits are global & bilateral in nature
Areas most prone to an anoxic brain injury from ischemia:
- Hippocampus: memory deficits
- Purkinje fibers of the cerebellum: ataxia
- Basal ganglia: increased muscle tone
Concerns for the Cerebellum
Cerebellar edema may develop, resulting in death from brain stem compression or herniation
Careful monitoring of brain stem signs
• Progressive LOC
• Coma
• Irregular breathing or respiratory arrest
• Irregular pulse or cardiac arrest
• Loss of all brainstem reflexes (blink, gag, pupillary reaction to light)
Management of Ischemic CVA of cerebellum
Posterior fossa decompression, for potentially fatal brainstem compression, can be life saving!
CT scan imagining: prevalence, uses, sensitivity
most commonly used
For large arteries, large veins, venous sinuses
Poor sensitivity for small infarcts and posterior fossa
MRI: why used
used when CT is not clear on
lesion location
Magnetic Resonance Angiography
T-PA medication : used for… contraindicated for… why u dont want to give them to pt. too late..
Given within 3 hours of onset to break up the thrombus to restore normal circulation
• Increases chance of recovery & minimize disability
Contraindicated for hemorrhagic strokes
Danger of giving these agents too late:
• Hemorrhagic infarction may occur
BP tx for Ischemic CVA and pt. position
Treat when PT has HTN. It prevents hypo-perfusion to infarcted area and helps delivers nutrition to the brain, decreases aggregation of platelets.
patient is kept for horizontal 1st few days post CVA, only can do bedside PROM
Other meds for ischemic CVA
Warfarin
ASA
Nimodepine: Ca2+ channel antagonist. has to be given within 12 hours of CVA!
Corticosteroids (Dexametasone): decreases edema
Treatment of choice for TIA and risk
carotid endearterectomy: remove atherosclerotic deposits from carotid artery
Risk: can dislodge a clot causing more sx!
Which is single most significant mod risk factor and why?
Hypertension- Aggravates atherosclerosis and can cause rupture of weakened blood vessel
walls
Local hypoglycemia leads to
Rapid depletion of energy stores and cell death
Core zone is where…
decreased supply of oxygen & glucose leads to rapid depletion of energy stores
(leads to neuron and glial cell death)
Ischemic Penumbra
-The area is still viable, but metabolically lethargic
The health of this tissue may be precarious…
This may explain some of the spontaneous recovery that occurs
Thrombotic ischemia is…
And how common
Most common type of all CVA (40%)
• Occurs in a vessel in cerebral vascular system, already partially occluded by atherosclerosis
Thrombotic CVA:
Frequently preceded by…
Frequently preceded by several TIAs
Which artery is most frequently involved
involved in MCA
When can a MRI not be used
CANNOT BE PERFORMED IF: Pacemaker,
other implantable devices
