stroke diagnosis & classification Flashcards
what is a stroke?
a clinical syndrome characterised by rapidly developing symptoms of a focal neurological deficit lasting >24hrs; thought to be of vascular origin
important factors to consider when determining if someone is having a stroke (3)
risk factors; consistency of symptoms - focal deficit leads to specific symptoms; handedness - speech centres in dominant side of the brain
What are the initial investigations for someone suspected of having a stroke (7)
- CT head;
- bloods - FBC, U&Es, blood sugar, cholesterol levels, ESR, clotting factors, APPL (if young);
- ECG (to look for AF, no p wave)
- CXR;
- CT perfusion/ MRI;
- Carotid doppler/CT angiogram;
- 24hr tape (look for PFO which can lead to a paradoxical embolism)/ echo/ prolonged cardiac monitoring
what is a patent foramen ovale
a congenital defect that results in a hole between the atrial septum occurring, this increases the risk of clots passing from the right atrium to the left and then being pumped up to the brain
what are the two types of stroke
ischaemic, haemorrhagic
what types of ischemic strokes are there (not classification - 8)
- small deep infarcts (lacunar);
- cardio-embolic (post MI);
- large artery infarcts (AF risk factor);
- extracranial occlusion;
- intracranial atherosclerosis;
- arterial dissection (carotid/vertebral usually)
- arteritis (e.g. GCA)
- cryptogenic
what types of haemorrhagic strokes are there (not classification - 5)
primary - amyloid angiopathic, hypertensive; secondary - AVM, aneurysm, coagulopathy
what is amyloid angiopathy
A condition in which amyloid proteins build up in the blood vessel walls, resulting in reduced flexibility and an increased risk of haemorrhagic stroke
why does hypertension increase the risk of stroke
blood vessels are damaged by constant high pressure, leading them to be more susceptible to haemorrhaging; atherosclerosis is also more likely to occur (narrowing of vessels + build up of fatty tissue) leading to higher chances clots and of ischemic stroke
What does a dark part on a CT scan indicate
dead tissue (i.e. that part of the brain has died)
What does a dark part on a CT scan indicate
dead tissue (i.e. that part of the brain has died)
what does a bright white part on a CT scan indicate
blood (i.e. a haemorrhage)
what is a CT perfusion
imaging which shows which areas of the brain are adequately supplied or perfused with blood and provides detailed information on delivery of blood or blood flow to the brain
what are the kinds of MRI scan that can be done (4)
- Diffusion weighted imaging - signal contrast generation based on the differences in Brownian motion of water molecules, used to evaluate molecular function and micro-architecture, most commonly performed if ischemic stroke is suspected and is more sensitive than other scans;
- Apparent diffusion coefficient - a type of DWI but contrast if the opposite to traditional DWI, lesions with reduced diffusion appear dark and those with elevated diffusion appear bright
- T1 weighted MRI
- T2 weighted MRI
How does DWI work (extra, just interesting lol)
the random diffusion of water molecules in brain tissue rapidly becomes restricted in ischemic brain tissue; During ischemia, the sodium - potassium pump shuts down and sodium accumulates intracellularly. Water then shifts from the extracellular to the intracellular space due to the osmotic gradient. As water movement becomes restricted intracellularly, this results in an extremely bright signal on DWI
