Stroke & TIA Flashcards
What is a stroke?
-Rapid development of symptoms/signs
-Focal loss of cerebral function
-Global loss with coma or SAH
-Lasts > 24 hours
-Presumed vascular origin
What are the 2 types of stroke?
-Ischaemic
-Haemorrhagic
What is an ischaemic stroke?
-Blockage reduces blood supply to area of brain tissue - results in tissue hypoperfusion
–> so is an atherosclerotic disease - caused by thick rough fatty deposits (called plaque) forming on inner wall of artery = blocks artery/narrows passage = little blood can pass through
OR -> blood clot gets stuck in artery - restricting blood flow
-Causes infarction of cerebral tissue
-Think of this as a blockage in the brain!
What is a haemorrhagic stroke?
-Occur secondary to rupture of blood vessel or abnormal vascular structure within brain
–> so blood from burst artery is forced into tissue of brain (= intracerebral haemorrhage)
OR -> forced into narrow space - subarachnoid space filled w/ CSF (= subarachnoid haemorrhage)
-Think of this as a bleed in the brain!
Give the prevalence of each type of stroke.
-Ischaemic = 85% - most common
-Haemorrhagic = 15% - least common
What is an intra-cerebral haemorrhage?
-Bleed from a blood vessel
-Variable prognosis
-Occasionally from an AVM (arteriovenous malformation) or tumour
What does an intra-cerebral haemorrhage look like on CT scan (haemorrhagic stroke)?
-Haemorrhage = white –> as iron & blood = dense
-Shown of right (on left = real life image)
How does an infarction occur (death of tissue resulting from a failure of blood supply, commonly due to obstruction of a blood vessel by a blood clot or narrowing of the blood-vessel channel)?
-Blood clot (thrombus) forms at site of hardened patch of artery in brain
-Usually affects small blood vs in brain
-Main RFs = hypertension, diabetes, smoking, lipids
What does a thrombosis in situ look like on CT scan (ischaemic stroke)?
-Thrombus = dark (grey) -> as the brain tissue liquifies when it becomes ischaemic - so less dense
So how do you differentiate between ischaemic & haemorrhagic strokes - as a 1st step?
CT scan - as they appear different
-Ischaemic = thrombus = dark grey - low density
-Haemorrhagic = intra-cerebral haemorrhage = white - high density
What are the 2 different types of infarct - of ischaemic strokes?
-Thrombotic stroke
-Embolic stroke
–> same end result = cerebral infarction downstream of blockage - different origin of thrombus
What is a thrombotic - ischaemic stroke?
-Atherosclerotic cerebral artery - thrombus forms on this artery - plaque rupture, then thrombus forms at site of blockage - then get stroke downstream
What is an embolic - ischaemic stroke?
-Thrombus embolises = travels through circulation from another site - doesn’t form at site of atherosclerosis
–> this is important - as you then know thrombus has come from somewhere else - so have problem somewhere else downstream in circulation
THROMBUS FORMS OUTSIDE BRAIN & THEN TRAVELS (EMBOLISES) TO THE BRAIN!
Where do embolic strokes normally originate - the thrombus?
*Carotid
*Heart - AF, irregular HR, severe LV systolic dysfunction, heart failure -> so can all cause clots in heart to embolise - then next downstream route is brain: from LV -> aortic valve -> aorta -> brain
-Could instead -> miss carotid & brachiocephalic trunk - instead down aorta but may hit mesenteric artery or iliac or tibial arteries
-» but statically as brain is 1st port of call from aortic arch - will hit here
Main risk factors of embolic strokes?
-Atrial Fibrillation
-Cardiac Failure
-Valvular Disease
-Diabetes
-Lipids
What is ischaemic penumbra - part of ischaemic stroke?
-When have ischaemic stroke -> have a blood clot blocking artery - reducing/stopping vertical blood flow - but may still have collateral blood flow
-So -> the vertical area of brain tissue will infarct rapidly - i.e., die/apoptosis/become necrotic –> 1.9 million neurones die per min
-However -> is still the collateral area of brain tissue supplied by this collateral blood supply - so this is a potential area to salvage some neurone/brain tissue -> if can reduce risk of this region (CALLED THE ISCHAEMIC PENUMBRA) from dying = lower total no. cells die = lowers neurological impairment = lowers overall subsequent disability from stroke
Give the stoke FAST mnemonic.
What does the ROSIER scale do/what is it?
= Validated scoring system to identify patients with ACUTE stroke from myriad other non-stroke conditions
-Used to rapidly determine a stroke from other potential differential diagnoses
-Score given = -2 to +5
-Higher score = more likely patient is/has had stroke
What is the Bamford Classification of strokes?
= divides people with stroke into 4 categories - according to signs & symptoms
-Use to understand underlying pathology
–> this in turn gives info on treatments likely to be useful & prognosis
-Easiest way to use = look for presence of 4 main features:
1. hemiparesis
2. higher cortical dysfunction (including language problems)
3. hemianopia
4. brainstem signs
–> then can classify stroke type as either:
-LACS
-PACS
-TACS
-POCS
What is re-perfusion therapy (for ischaemic strokes only)?
= any treatment that tries to reperfuse regions of the brain that have been blocked off - i.e., get rid of clots to restore blood flow to a previously ischaemic organ/tissue
How - 2 ways
1. Dissolve clot with drug - IV thrombolysis
2. Mechanical thrombectomy - physically go into blocked artery & extract clot - with some device
–> both show to be beneficial in reducing neurological impairment if given soon enough
(Image shows how we know this is effective)
