Neurovascular disorders (done) Flashcards
What is a stroke?
Acute onset of neurological deficits (lasting more than 24hrs due to a disturbance in blood supply
How many ppl suffer from strokes each year?
Approx 15 million
What are the 2 categories of risk factors for a stroke?
- Non-modifiable
- Modifiable
What are the modifiable risk factors of a stroke?
& how much can some inc chances by?
- Hypertension (high BP)
- Diabetes
- Hyperlipidemia (high cholesterol)
- Smoking = 50% inc
- Obesity = 3x inc
- Carotid artery disease
What are the non-modifiable risk factors of a stroke?
(Give specifics for some pls)
- Age (avg 68-73)
- Atrial fibrillation
- Gender
- Ethnicity
- Family history
How can gender affect the chances of having a stroke?
Women are less likely until menopause
The strokes that occur during menopause tend to be worse
Why is it so important to understand strokes?
It is the 3rd largest cause of death
15 million ppl suffer a stroke each year:
1/3 will die, 1/3 recover & 1/3 have lasting effects
What are the 2 main divisions of strokes?
How common is each type?
Ischemic (85%)
Haemorrhagic (15%) = least common type
What is a Haemorrhagic stroke?
Bleeding in the brain from ruptured blood vessel –> there are 2 types
(Some more context = Deprives brain cells of O2 & nutrients - damaged cells can’t func = lasting damage)
What are the 2 types of Haemorrhagic stroke?
How common are each of them?
- Intracerebral - 10%
- Subarachnoid - 5%
What is an intracerebral stroke (haemorrhage)?
A type of Haemorrhagic stroke (the more common type)
Bleeding occurs within brain tissue itself
What is a a subarachnoid stroke (haemorrhage)?
A type of haemorrhagic stroke (less common type)
Bleeding occurs between brain & subarachnoid space
These are rarer than intracerebral but are more devastating
What are the 2 types of ischemic stroke?
How common is each type?
- Thrombotic - 55%
- Embolic - 30%
What is an ischemic stroke?
The blood supply to the brain is blocked or stopped
Can be caused by blood clots or artery narrowing
What is an thrombotic stroke?
The more common type of an ischemic stroke (55%)
Caused by a blood clot (thrombus) formed in the arteries supplying blood to the brain
Blockage cuts off blood flow = stroke
What is an embolic stroke?
The less common type of an ischemic stroke (30%)
Caused by a blood clot (embolus) formed ELSEWHERE in the body & travels to block an artery supplying blood to the brain
What is the difference between a lacunar occlusion & a large vessel occlusion
Lacunar occlusion
- Blockage of small arteries deep in the brain tissue
- Can be caused only by thrombotic stroke
Large vessel occlusion
- Blockage in major artery of the brain
- Can b caused by either thrombotic or embolic stroke
What are the 4 areas that symptoms of a stroke can arise from?
- Haemorrhage
- Anterior circulation
- Posterior circulation
- Non-specific symptoms
What are the symptoms of a haemorrhage?
- Thunderclap headache
- Seizures
- Nausea
- Unilateral weakness
What type of stroke is anterior circulation most common in?
An ischemic stroke (70%)
What are the symptoms of anterior circulation issues in a stroke?
- Hemiplegia (paralysis)/paresis (weakness) of one side of body
- Hemisensory loss (loss of sensation)
- Dysphasia (difficulty producing/understanding words)
- Aphasia (same as above)
- Hemianopia (partial loss of vision)
(Most commonly seen in ischemic stroke)
What are the symptoms of posterior circulation in a stroke?
- Unilateral limb weakness (weakness one side of body)
- Ataxia (lack of voluntary coordination of muscles movement)
- Dysarthria (difficulty forming & pronouncing words)
- Hemianopia - isolated (vision loss)
What are the non-specific symptoms of a stroke?
- Confusion, drowsiness, dizziness
- Nausea, double vision
- Incontinence
What symptom can indicate to us in isolation that a posterior circulation stroke is occurring?
Hemianopia (loss of vision in both eyes)
What happens in the brain in a lacunar infarction?
Small, strategic strokes happen in penetrating arteries that feed sub-cortical structures
What % of lacunar infarctions are silent?
As many as 80% are clinically silent
What is motor hemiplegia syndrome?
What type of infarction is it?
Infacrtion in the internal capsule, basal ganglia &/or pons
A lacunar infarction
Why can lacunar infarctions be just as devastating, even though they’re only small strokes?
Many occur in the basal ganglia & internal capsule (motor hemiplegia syndrome)
These are major movement areas –> so can cause huge issues
What can cause stroke symptoms to vary?
- The blood vessel involved
- The size of the lesion
- The region of the brain affected (anterior or posterior circulation)
What is the most common stroke?
What does it result in?
Middle cerebral artery infarction
Results in contralateral hemiplegia & hemiosensory loss
How are strokes identified?
A neurological examination is followed by urgent referral for neuroimaging
Neuroimaging generally done by CT (computed tomography) –> this can detect haemorrhage
What is the issue with using CT scan to detect strokes?
It is not as effective at detecting acute ischemic stroke (can see it slightly as the sulci become less defined
Good for hemorrhagic strokes tho
What % of ppl who have a brain haemorrhage die?
45%
What is vasospasm & what is the chance of getting this from a haemorrhage?
Blood vessels (once haemorrhaged) start to spasm & constrict
This can result in an ischemic stroke
How is a brain haemorrhage treated?
(Must be treated as brain haemorrhage won’t treat itself
Treatment involves:
- Pain management
- Surgery to repair the bleed using clipping or coiling
- This may include lowing BP
What happens when a blood vessel is clipped?
Small metal clip placed at the base to block blood flow & clip the vessel
How is coiling used to treat a haemorrhage?
Inject an opaque dye into blood vessels to see the problem area
They fill the aneurism with wires & this stops blood flowing out more
This is done as blood vessel is hard to reach
What is the first treatment used when someone has an ischemic stroke?
Thrombolysis using TPA (tissue plasminogen activator)
Brand normally used = Altepase
How soon does thrombolysis using TPA need to be given after an ishcemic stroke?
Given within 3-4.5 hours
(Has been shown to work after 6 hours tho)
What is the other option to treat ischemic stroke after Thrombolysis?
If TPA hasn’t worked:
A Thrombectomy –> a retriever device removes the clot
How long after the stroke must a thrombectomy be performed?
Within 6 hours of the stroke
(If TPA hasn’t worked)
What are the 4 areas involved in the concept of the penumbra?
- Core
- Penumbra
- Benign oligemia
- Normal tissue
During a stroke how much blood flow is the following regions getting?
- Core = <12mL/100g/min
- Penumbra = 12-22mL/100g/min
- Benign oligemia = >22mL/100g/min
- Normal tissue = 50-54mL/100g/min
What is the importance of the penumbra?
The penumbra is the area surrounding the core region of the stroke
Cells in the core are already dead (lack of blood flow = lack of O2 = loss of func)
Penumbra has reduced but not absent blood flow –> cells have not yet died
If a stroke is treated quickly what happens to the penumbra?
The blood flow can return to the cells & they can be saved & regain function
IF not treated quickly these cells may die along with the core
What are the 4 stages in the time course of events in a stroke?
When do these events occur?
- Excitotoxicity = minutes (decreases at hours)
- Peri-infarct depolarisations = same as above
- Inflammation = Hours - days
- Apoptosis = hours - days (inc more at days)
What is excitotoxicity in a stroke?
During stroke, excessive release of glutamate = excitotoxicity
This is what kills a lot of the cells
What are peri-infarct depolarisations in a stroke?
PIDs are waves of neuronal & glial depolarisation that propagate thru the penumbra & sometimes into healthy brain tissue
What effect to peri-infarct depolarisations (PIDs) have on the brain in a stroke?
They worsen the damage int he penumbra - speeding past the core cells
What is inflammation like after a stroke?
Not as high of an impact as the other symptoms but still affects cells
Can go on for days after
How does inflammation after a stroke work?
It is the body’s immune system attempting to repair –> sends cells such as WBCs to the ares
HOWEVER –> prolonged inflammatory response = harmful
Cytokines can be released in this process & if too many released = damage healthy tissue around stroke site
When does apoptosis occur during a stroke & what effect does it have?
After all the other types of damage, cell death occurs last
Programmed cell death, particularly in the penumbra
What happens in a cell when there is a stroke?
(This is a long process & may need to refer to diagram)
- Blood flow blocked = cell deprived of O2 & glucose (energy failure)
- Depolarisation = influx of Na+ & Ca2+ into cell & K+ out
- Stressed cell releases excessive glutamate & builds up outside cell –> spreads to other cells & causes depolarisation
- Cell swells
- Ca2+ influx activates enzymes that damage cellular structures –> creates free radicals, these are unstable & cause more damage
- Causes membrane to weaken & DNA damage means this can’t repair
- Damaged cell starts inflammatory response –> this activates microglia & causes leukocyte infiltration
- Cell death = cell death pathways activated (either apoptosis or necrosis)
What is inflammation like in the brain after a stroke?
- Neuronal damage = cells are depolarising = glutamate toxicity = cytokines activated
- These cytokines activate microglia (immune cells of the brain) –> microglia release their own cytokines (positive feedback loop)
- BBB is damaged –> means leukocytes that can’t normally enter now can (they also contribute more damage)
What is vascular cognitive impairment (VCI)?
An umbrella term for many cognitive disorders thought to share vascular origin
The same vascular risk factors that predispose someone to a stroke also inc the risk of what?
Developing dementia
What neurodegenerative disease is sometimes classified as a vascular cognitive impairment?
& why?
Alzheimer’s
As many as 50% of brains w classic AZ pathology show evidence of cerebrovascular disease
What are the main pathologies seen in cerebrovascular disease (VCI)?
- Cerebral amyloid angiopathy
- White matter change
- Large vessel occlusion
- Atrophy (loss of volume)
- Lobar & deep haemorrhage
- Infarcts
- Enlarged perivascular spaces
- Microbleeds
What are cerebral amyloid angiopathys?
Beta amyloid plaques –> these accumulate in the brain
Condition where these accumulate around blood vessels in VCI diseases –> leads to blood flow problems
What are the changes seen in white matter in VCI diseases?
- Small lesions
- Loss of volume
- Disruption of myelin
What are lobar & deep haemorrhages in VCI?
- Lobare occur in lobes of brain
- Deep occur in the deep structures of the brain
What are infarcts in VCI?
Refer to areas of dead tissue in the brain caused by lack of blood flow
If not recovered quickly - cells here will die
What are enlarged perivascular spaces in VCI?
Perivascular spaces = Fluid filled cavities that surround small blood vessels in brain
Enlarged = fluid fills up outside blood vessels
