Basics of a stroke Flashcards
What are the key features of a stroke?
Rapid onset
Focal loss of cerebral function
May have a global loss of function in the form of a coma or SAH
Lasts longer than 24 hours
Presumed vascular origin
What are the two different types of stroke?
1) Ischemic - thrombis or embolism
2) Hemorrhagic - intercerebral (between brain tissue) or subarachnoid (between pia and arachnoid mater)
What is an intercerebral haemorrhage?
Bleed from a blood vessel
Variables prognosis
Occasionally from an AVM
What does a intercerebral haemorrhage look like on an MRI?
Immediate appearance
Looks white - as blood and iron are dense
May spread over time
How does infarction occur?
Thrombus forms at sites of hardened patches of artery
Usually affects the small blood vessels
What does an infarction stroke look like on an MRI?
Grey area, develops six to 12 hours after the ischemic event starts
Brain tissue goes liquid like in density as ischemic damage occurs.
What are the risk factors for an embolism?
Atrial fibrilation
Cardiac failure
Valvular disease
Diabetes
Lipids
Where are embolism most likley to form?
Why does the prognosis for a stroke vary compared to a thrmobus?
Embolism - carotid artery or heart
Normally larger, blocks larger blood vessels results in more downstream tissue damage/death
What is meant by the ischaemic penumbra in a stroke?
Thrmobus blocks are artery
Regions that die quickly is the necrotic area
Surrounding area that is at risk but is not yet dead is the inschaemic penumbra, this region is also supplied by arteries known as collateral flow
Treatment should focus on resorting and preventing gurther damage to these arteries
How fast does damage from stroke occur?
1.9 million neurons a minute
What is a TIA?
A transient ischaemic attack
Acute loss of focal cerebral function
Or
Acute monocular visual loss (retinal artery blocked)
Lasts less than 24hrs
Indicates an increased risk of stroke, referred for help immediately
How does a thrombus/embolism get removed in a TIA?
Endogenous throbolytic mechanisms
Degrade or dissolve the thrombis, hence lack of oxygen is temporary.
What is the rosier scale in stroke recognition?
ROSIER - recognition of stroke in the emergency room
Generates a score from -2 to 5, higher score means a stroke is more likely.
Based on seizures and syncope (-1 each) then the BEFAST.
Aims to help distinguish between stroke and conditions that share symptoms with stroke
What proportion of ‘stroke’ patients in A and E are stroke patients?
50% of patients that present with stroke like symtpoms actually have stroke
What are some common non-stoke diagnosis with similar symptoms?
Seizure
Syncope
Sepsis
Migraine
Orthostatic hypotension
Labrynthitis
In differential diagnosis what symptoms are more likley to happen in a stroke?
Acute onset ***
Arm weakness
Leg weakness
Facial Weakness
Speech disturbance