Treatments and prevention of stroke Flashcards
Diagnosing strokes
the kind of treatment the person gets very much depends on the type of stroke that has occurred
- critical that the type of stroke is identified BEFORE treatment of any kind
ISCHAEMIC vs HAEMORRHAGIC
I = clot blocks off blood vessel in brain H = ruptured blood vessels leading to bleeding into the brain
CT scans what is it? Ischaemic? - when can you see changes? mins - hours 12-18hrs 48hrs
computerised tomography
A special type of X-ray that take lots of images from different angles and levels
- the normal brain looks symmetrical
- brain a few mins after an ischaemic stroke or even an hour after would look the same as normal
–> because, changes in the brain during and after a stroke take time to detect
(Sometimes you can’t see any brain changes on CT until about 1/2 day after the I stroke has occurred)
- want to make sure it’s not haemorrhagic
ISCHAEMIC:
12-18hrs = start to see some changes on the CT scan(might be able to see clot)
48hrs = see swelling and bulging due to inflammation, and ventricles reduce in size –> treatment crucial early on
HAEMORRHAGIC
- CT scans v good for diagnosing haemorrhagic stroke because blood leaking out of your cerebral circulation and into your brain shows up really well on CT scans (bright white regions)
MRI
more sensitive for detecting ischaemic stroke, but less available and take longer
- can detect changes in the brain about half an hour after the stroke occurs
- MRI images show how much blood flow is running through the brain
zones of injury in an ischaemic stroke
- ischaemic core
- penumbra
- ischaemic core: zone closest to the artery that has been blocked off
characteristics: blood flow less than 20%, loss of 02 and glucose, neuronal cell death = necrosis, cells die within minutes - penumbra (2nd zone): this area surrounds the core and the tissue in this region is moderately ischaemic
- -> penumbra is the area where medication is most likely to be effective. One of the goals of treatment is to break up that clot and to get blood back into that ischaemic area
- treatment tries to focus on this area as there is still some blood supply here meaning cells are more likely to survive (once cells are dead = can’t help)
- cells will die within hours without treatment
timing is v important = quick as poss
(progression of injury
Treatment of ischaemic stoke
- thrombolytic
- limitations
thrombolysis is likely to only be used on 10% of patients who have strokes (Hankey and Warlow)
break down the blood clot that is currently causing the blockage
aspirin/ anticoagulants
- tissue plasminogen activator (TPA)
= the only approved treatment for I stroke
HOW? - activates a compound called plasminogen already floating around in the blood
plasminogen –TPA–> plasmin
(plasmin = the compound that breaks down the clot
- most effective when administered within 3-4hours of the stroke occurring (therapeutic time window)
- as time goes on it becomes less and less effective
(aspirin given immediately to prevent other clots forming)
Limitations:
- limited therapeutic time window
- risk of haemorrhage
- consider other health issues/ medications
Ischaemic
- surgical treatment
a) MERCI retriever
b) suction removal
usually only considered if the patient isn’t responding to the thrombolytic treatment
a) MERCI retriever
= 1st ever surgical treatment to remove clot after acute ischaemic stroke
(mechanical embolus removal in cerebral ischaemia)
HOW
-surgeon will insert wire into blocked artery
-wire is pushed up into the artery just past the clot
-wire is inside a sheath and when sheath is removed the wire begins to coil up, and the wire is slowly retracted, so it catches the clot and both the clot and wire are then removed = blood flow restored
b) suction removal
- surgeon inserts a tube up into the artery, from here a little wire is put through the tube and positioned so its right behind the clot
- wire pushed back and forth to break the clot into smaller pieces, and then the tube starts to suck up the pieces
Treatment of haemorrhagic stroke
- managing symptoms
need to locate the bleed in the brain and determine which blood vessel is affected
- to do this, need a more advanced CT scan
- patient may be given antihypertensives to reduce blood pressure
- build up of blood in the brain can increase the pressure and this pressure may lead to further problems eg. seizures (reduce pressure by elevating head)
- pressure can also push on brain stem (responsible for breathing and heart rate) which can be fatal
GOAL = manage symptoms
(Can drill into skull to retrieve pressure = last resort)
Treatment of haemorrhagic stroke
Surgical treatment
a) aneurysm clipping
b) coil embolisation
a) aneurysm clipping - clip gets put onto the base of the aneurysm = blocks blood from moving through and blood flow resumes on usual artery pathway
b) coil embolization - insert tube into artery until it hits the opening of the aneurysm. Then, the flexible wire gets threaded through the tube and it starts to coil up inside the aneurysm.
- more and more wire gets pushed up aneurysm and it coils until no blood can get through to the aneurysm and normal route is resumed
= in the aneurysm the blood begins to clot up and stop any bleeding
Summary of treatments?
Ischaemic
- aspirin (preventative)
- thrombolysis
- MERCI retriever
- suction removal
Haemorrhagic
- managing symtoms
- aneurysm clipping
- coil embolisation
Prevention
- reduce risk of stroke by tackling risk factors
Initially: diet and exercise (lower blood pressure + cholesterol levels, prevent diabetes and help lose weight) - drinking reduction, smoking reduction, reduce stress
- lifestyle changes not quick enough = prescribed medication
Risk factors of stroke: non- modifiable
= things that you can’t control such as:
1) family history
- strokes seem to run in families, so your risk goes up if one of your immediate relatives has had a stroke
2) age
- as you get older, risk increases
- young blood vessels are usually nice and healthy = strong artery walls
- older = walls become:
weaker with age = more likely to rupture and therefore likely to cause haemorrhagic stroke
stiffer = due to build up of fatty compounds, which puts you at higher risk of developing hypertension (high blood pressure)
-greatest risk = 65+
3) gender
- contradictory research regarding gender (due to risk factors)
-pre menopause women have higher levels of progesterone = less likely to have stroke
- post menopause women have around same risk as men
BUT, women live longer = higher chance of having stroke
4) Ethnicity
- some ethnic minorities have hypertensions more than others
Modifiable risk factors
-hypertension - 2 ways it can cause stroke? (I + H)
-hypertension, cardiac diseases, diabetes, high cholesterol, lifestyle factors eg. cigarette smoking, obesity, lack of exercise, alcohol
– Hypertension
1) normal blood pressure = all red blood cells travel through cerebral vessels at normal speed (not too fast, so they don’t damage vessels)
- high blood pressure = red blood cells move faster and so bump into walls = problem fo small er vessels so they compensate for extra pressure with thicker walls = smaller diameter, so not as much blood can travel through
(receiving this limited blood or no blood = brain tissue will die and stroke will occur = ischaemic)
2) 2nd way it can increase risk of stroke is when blood rushes past a junction they will continuously bump into the edge = causes vessel to balloon out
= tendency to rupture and bleed into brain = haemorrhagic stroke
Modifiable risk factor
Cholesterol - 2 ways it can cause stroke
– high cholesterol
-caused by diabetes, smoking and high cholesterol
(at high concentrations glucose damages blood vessel walls by making them hard and stiff), toxins in smoking also damage blood vessels
- cholesterol can sit in damaged areas in blood vessel wall and build up there = antherosclerosis
can cause 2 things:
1) big cholesterol formation can crack open, cause a clot to form on top and block off entire blood vessel
2) piece of cholesterol collection can break off and float downstream to block off smaller vessel
= both result in depriving brain tissue of blood downstream = stroke
AR?
= absolute risk, the number of events (good or bad) in a control group or treatment group divided by the number of people in that group
(ART = absolute risk in treatment group, ARC = absolute risk in control group)
