Cerebrovascular Disease Flashcards
What causes a subdural haemorrhage
Tearing of the bridging veins
Very delicate so happens easily
Common in the elderly when they fall
What is the function of the oligodendrocytes
Produce the myelin sheath in the CNS
What happens to nerve cells when they are damaged
Rapid necrosis with acute functional failure -seen in stroke
Slow atrophy with gradual increasing dysfunction - seen in dementia
When would you see a red neuron
After neuronal cell death in the context of ischaemia
Cytoplasm will be red on histology
Nuclei shrink and become angulated
In which conditions are the oligodendrocytes damaged
Demyelinating disorders - MS
Sensitive to oxidative damage as well
What are the functions of astrocytes
Ionic, metabolic and nutritional homeostasis
Maintain the BBB and regulate blood flow
Repair and scar formation
What is gliosis
Indicator of CNS injury - response from the astrocytes
Increase in the number and size of astrocytes
Can become a glial scar - dense area of processes
How do ependymal cells respond to injury
Limited response
Infectious agents can produce changes in them
What is the function of the microglia
They mop up debris in the brain - phagocytosis
Aggregate around areas of damage and necrosis
Recruited by inflammatory mediators
What can cause injury to the nervous system
Hypoxia Trauma Toxins - endogenous or exogenous Metabolic abnormalities Nutritional deficiency Infections Genetic abnormalities Ageing
What can cause brain hypoxia
Cerebral ischaemia Infarct, Haemorrhages Trauma Cardiac arrest Cerebral palsy
Why is the brain so sensitive to hypoxia
It consumes 20% of the body’s oxygen at rest
So needs consistent oxygenation to function
Will use up ATP stores within minutes without aerobic respiration
What is excitotoxicity
Mediator of neuronal injury
Glutamate accumulates as the reuptake is interrupted
Post-synaptic channels are excited which leads to rapid accumulation in Ca+
This can lead to death of the neuron
What types of oedema can affect the brain
Cytotoxic oedema - water and NaCl move into the cytoplasm of cells
Ionic oedema - osmosis which occurs in excess water intake and hyponatraemia
Vasogenic - occurs in trauma, inflammation and tumours
How much of the cardiac output does the brain receive
15%
Also consumes 20% of the oxygen
How does the brain maintain constant blood flow
Autoregulatory mechanisms can control the dilation and constriction of cerebral vessels to maintain an appropriate pressure
When is the autoregulation of blood pressure in the brain no longer efficient
The regulatory methods will be exhausted at either very high pressures (>160) or very low (<60)
This will lead to issues with flow and oxygenation
What is cerebrovascular disease
Any abnormality of brain caused by a pathological process of blood vessels
Common cause of death and adult disability
What causes global hypoxic ischaemic damage
Generalised reduction in blood flow or oxygenation
Cardiac arrest
Severe hypotension - e.g. after trauma with hypovolemic shock
What causes focal ischaemic damage
Vascular obstruction
Thrombus or emboli
What are the watershed areas of the brain
The zones between 2 arterial territories
They are particularly sensitive to ischaemic injury
What is the definition of a stroke
Sudden disturbance of cerebral function of vascular origin that causes death or lasts over 24 hours
What is the most common type of stroke
Ischaemic
Most commonly due to a thrombus
Embolic strokes also happen but aren’t as common
What are the different types of haemorrhagic stroke
Intracerebral - most common
Subarachnoid
Bleeding into an infarct - haemorrhagic transformation
Which brain artery is most commonly affected by thrombosis
Middle cerebral artery and its territory
Where do the emboli that cause strokes commonly come from
From atheroma in internal carotid and aortic arch
Heart - AF
What are the risk factors for ischaemic stroke
Atheroma Hypertension Obesity and high serum lipids Diabetes mellitus Heart and vessel disease Disease of the neck arteries AF Patent foramen ovale Arterial dissection Drugs Smoking
What factors determine the extent of damage in a cerebral infarction
The territory supplied by the affected artery
Timescale of the occlusion
Extent of the collateral circulatory relief
Systemic perfusion pressure
How long after a stroke does gliosis occur
Around 1 week
Microglia will be the dominant cell type on microscopy
At what point does brain damage become visible after infarction
12-24hrs after
On microscopy you will see red neurons and oedema
To the naked eye the brain is pale and slightly swollen - more visible after 48hrs
What are the symptoms of infarct in the carotid arteries
Contra‐lateral weakness or sensory loss
If dominant hemisphere, may be aphasia or apraxia
What are the symptoms of infarct in the middle cerebral arteries
Weakness will be predominantly in the contralateral face and arm
What are the symptoms of infarct in the anterior cerebral artery
Weakness and sensory loss in the contralateral leg
What are the symptoms of infarct in the vertebral or basilar arteries
Vertigo
Ataxia
Dysarthria
Dysphasia
What effect does hypertension have on the brain
Accelerated atherosclerosis
Microaneurysms
Higher risk of stroke (lacunar particularly)
Risk of rupturing aneurysm and general haemorrhage
Can get hypertensive encephalopathy
What happens in hypertensive encephalopathy
Global cerebral oedema
Tentorial and tonsillar herniation
Petechiae
Arteriolar necrosis
What can cause an intracranial haemorrhage
Can be spontaneous Trauma Hypertension Aneurysms Coagulation disorders Anticoagulants Vascular malformations Amyloid deposits Diabetes Vasculitis Drugs and alcohol
Where do intracerebral haemorrhages most commonly occur
Basal ganglia is the most common
Also thalamus, cerebral white matter and cerebellum
What surrounds a haemorrhage in the brain
Significant oedema
This in itself will contribute to brain damage
What is amyloid angiopathy
You get deposits of amyloid proteins which stick together
Affects the blood vessels - aren’t as flexible and cant respond to changes in BP
This makes them more likely to rupture
What are the risks with vascular malformations
Can lead to haemorrhage - AVM or cavernous angiomas are most likely to
Can also lead to headaches, seizures and focal neurological deficits
Do all vascular malformations cause stroke
Nope
Some can be small incidental findings
Describe arteriovenous malformations
It is an abnormal tortuous vessel where there is shunting from an artery to a vein
These will undergo smooth muscle hypertrophy
They are not very compliant and so rupture easily
Can also form aneurysms
What causes a subarachnoid haemorrhage
Most commonly due to spontaneous rupture of a berry aneurysm in the circle of Willis
Can be due to trauma
What are the risk factors for a subarachnoid haemorrhage
Smoking
Hypertension
Kidney disease - PCKD is associated with berry aneurysms
Women often more commonly affected
What are the symptoms of a subarachnoid haemorrhage
Severe headache - thunderclap Worst headache they've ever had Vomiting Loss of consciousness Usually no history or precipitating factor
What is the mortality and morbidity like for subarachnoid haemorrhage
50% will die after a few days
Survivors are at risk of hydrocephalus
What are the 4 main classes of stroke
Total anterior circulation infarct (TACI)
Partial anterior circulation infarct (PACI)
Lacunar infarct (LACI)
Posterior circulation infarct (POCI)
Which class of stroke is considered the most severe
Total anterior circulation infarct (TACI)
This is because it has the greatest amount of brain damage
What are the key signs of TACI
4 main features:
Hemiplegia involving at least 2 of face, arm and leg
Hemisensory loss/deficit
Homonymous hemianopia
Cortical signs - dysphasia, neglect of one side, cognitive issue etc.
What are the key signs of PACI
Any 2 out of 4 features of TACI (hemiplegia, hemisensory issue hemianopia, cortical signs)
OR
Isolated cortical dysfunction such as dysphasia
OR
Pure motor/sensory signs less severe than in lacunar
What are lacunar infarcts
Small infarcts in the deeper parts of the brain or in the brainstem
Can affect the basal ganglia, thalamus or white matter or brainstem
Caused by the occlusion of a single, deep penetrating artery
How does a lacunar infarct present
Can be a pure motor stroke - hemiplegia affecting 2 from face, arms or legs
Can also be purely sensory or sensorimotor
May present with ataxic hemiparesis
Or may go unrecognised if not in a clinically relevant area
Has no cortical signs
Higher cerebral function/cognition preserved
What are some risk factors for lacunar stroke
Hypertension
Diabetes
Smoking
How does posterior circulation syndrome/infarcts present
Symptoms and signs fit the vertebrobasilar system (vertigo, ataxia, dysarthria) or brainstem
Cranial nerve palsies Bilateral motor and/or sensory deficits Conjugate eye movement disorders Isolated homonymous hemianopia - PCA supplies the occipital lobe Cortical blindness Cerebellar deficits Can lead to locked in syndrome
Infarcts/events in the left hemisphere (usually dominant) causes what issues?
Often affects language and communication
Dysphasia, agnosia and dysarthria
More involved in sensory functions
Implications in rehab
Infarcts/events in the right hemisphere (usually non-dominant) causes what issues?
Affect spatial awareness - neglect or sensory inattention
Usually more involved in motor functions
Can however cause personality change
What type of thrombus is a carotid plaque (usually)
Tend to be white thrombi - platelet rich
Therefore need to be treated with antiplatelets
What type of clot is a cardiac embolism (usually)
They tend to be red clots - protein rich
Should be treated with anticoagulants
How can you check for carotid artery disease
Carotid US - looks for narrowing of the arteries
CT/MRI angiogram can give you a clearer picture
What are the classifications of small vessel disease
Type 1 - arteriosclerotic (associated with typical CV risk factors)
Type 2 - Sporadic and hereditary cerebral amyloid angiopathy
Type 3 - other genetic disease
Type 4 - inflammatory and immunologically mediated
Type 5 - venous collagenosis
Type 6 - other
Where do most cardiac emboli come from
Due to atrial fibrillation
5x higher risk of stroke if you have AF
When might you consider patent foramen ovale as a cause of stroke
In a young person with no other cardiac risk factors
Congenital defect in the heart - close surgically when young to lower stroke risk
How can an arterial dissection lead to stroke
Tear in the arterial wall sets of the clotting cascade which can then embolise
What can cause an arterial dissection
Hypertension
trauma
Sudden movement
What are the causes of primary intracerebral haemorrhage
Hypertension
Amyloid angiopathy
What are the causes of secondary intracerebral haemorrhage
AVM
Aneurysms
Tumours
How do haematomas expand in the brain
Will continue to bleed for a while after onset
Oedema that occurs around a bleed will set of an inflammatory cascade that can lead to secondary bleeds
Therefore it gets bigger over time
What are the main parts of stroke prevention
Anti-thrombotic therapy - either anti-platelets or anticoagulants Blood pressure control Cholesterol control Diabetes control DONT smoke
Which score can be used to assess the risk of stroke
CHA2DS2VASc
What score can be used to assess the risk of bleeding/haemorrhage
HAS-BLED
What is one of the biggest risk factors for haemorrhage
Anticoagulation treatment
However the treatment is usually so beneficial that the risk is accepted
What is a carotid endarterectomy
Surgical procedure where the artery is opened and the plaques physically cleared out
They also hoover up any other clots in the area
Reduces stroke risk
How do you manage dysphagia after a stroke
Initial swallow screen
If abnormal get them assessed by speech and language therapy
May need textured diet, fluid diet or NG tube
What are the major complications of dysphagia after a stroke
Choking and aspiration risk
Risk of dehydration and malnutrition
How do you diagnose a SAH
Urgent CT head scan
Should see blood - appears bright white on non-contrast CT
If this is negative but they have signs that don’t improve you do a LP 12 hours later and test for bilirubin (breakdown of the blood that has leaked into the CSF)
Can’t do immediate LP as fresh blood could be due to LP trauma and give a false positive
Are all intracranial haemorrhages considered strokes
No
Extradural, subdural and subarachnoid are not strokes
Only intracerebral are true strokes - damage to brain itself not due to compression
When someone regains function after a stroke it is because the damage is reversing, true or false
False
It is other parts of the brain that take over with training/rehab - neuroplasticity
Damage is irreversible
Stroke is a purely clinical diagnosis - true or false
True
Imaging is mainly used to rule out other causes
List causes of haemorrhagic stroke
Hypertension (most common)
Vasculitis
Vessel wall abnormality - aneurysm, AVM, amyloid angiopathy
Anticoagulants or bleeding issues can make it worse - not main cause but contributes
Bleeding from tumours - not quite a stroke
Surgery is commonly used in stroke treatment - true or false
False
It will do nothing to reverse the damage so it is only used if there is a risk to life such as coning/hydrocephalus
It is used for extracerebral haemorrhage as it relieves compression which is the cause of the damage
What are the hyperacute stroke treatments
Thrombolysis - used within 4.5 hours
Thrombectomy - used up to 6 hours
Hyperacute treatment is only used in which type of stroke
Ischaemic
Have a small window for prevention of further ischaemic damage by unblocking the vessel
Aim is to reduce disability and mortality
Describe thrombolysis
A stroke treatment where a clot dissolving drug (alteplase) is given IV
Only work if within 4.5 hours of onset
Describe thrombectomy
A catheter is inserted into the vessel and the clot is physically removed
Only used for large vessel proximal occlusion as catheter can reach here (can’t get to tiny lacunar ones)
Only done in certain centres as you need a lot of equipment and expertise
List common stroke mimics
Migraine Post-seizure Hypoglycaemia Acute presentation of SOL Demyelination Bell's palsy
Why does arteriosclerosis increase the risk of haemorrhagic stroke
It makes the vessels stiff so they are not as resistant to spikes in blood pressure - can cause rupture which would cause the stroke
What is the difference between atherosclerosis and arteriosclerosis
Atherosclerosis is plaque formation in vessels- caused by classic risk factors
Arteriosclerosis is a thickening of the artery wall - caused by ageing (sped up by hypertension)
How do you differentiate between ischaemic and haemorrhagic stroke
Only way is via imaging
How does a lobar brain haemorrhage appear on imaging
It is superficial/peripheral and large
The collateral blood supply of the brain created by the circle of WIllis can prevent a stroke - true or false
Bit of both!
Cannot prevent a stroke if a major supply vessel is suddenly blocked
However, it can prevent minor strokes or damage due to gradual loss of vessels (e.g. atherosclerosis as brain has time to adapt)
What structure provides the brain with a collateral blood supply
The circle of Willis
What are the perforating arteries of the brain
Smaller vessels which arise from the main trunk of the major vessels and perfuse the deep section of the brain
If a stroke has occurred in multiple vascular territories, what is the likely cause
Emboli - most commonly from AF as this throws off a lot of clots from the heart
Which arteries are affected in a small vessel occlusion stroke
The perforating arteries
Strokes blocking one of these vessels will be smaller as they supply smaller areas
Explain the situation where a small vessel occlusion can be extremely damaging
Can still be severe as can affect the internal capsule - where everything comes together so a lot of structures affected at once
Which type of clot typically causes a large vessel occlusion
Embolus
To cause stroke it must be sudden and thrombi take time to build up
Which type of clot typically causes a small vessel occlusion
Thrombus
What is the difference between expressive and receptive dysphasia
Expressive/motor - non-fluent, jargon speech, can understand but not talk
Receptive/sensory - can speak fluently but not understand
May have a mix
What is agnosia
Failure to recognise an object despite having an intact sensory system
I.e. cannot recognise a well known object by touch alone
What is dysarthria
Slurring of speech
Does not need to have a neurological cause
Which artery is affected in a TACI
The middle cerebral artery
Supplies both motor and sensory areas so get deficits in both
What is the Oxford classification used for in stroke medicine
Developed to guide management of stroke
Clinical classification only
Applies to both ischaemic and haemorrhagic
Which lobe of the brain is supplied by the anterior cerebral artery
Frontal lobe
Cortical signs are characteristic of which types of stroke
TACI and PACI
TACI and PACI are usually embolic strokes - true or false
True!
Which type of stroke might present with a headache
Posterior circulation stroke
Unusual presentation for stroke except this type
Which type of stroke is usually the least damaging
Lacunar
Less brain damage - more chance for recovery due to neuroplasticity
Posterior circulation strokes are always embolic - true or false
False
can be embolic or thrombotic
List the 5 sections of the TOAST classification for ischaemic stroke
1 - cardioembolic (mainly AF)
2- large vessel atheroembolic (from atherosclerosis in large vessel)
3 - small vessel - usually thrombotic disease
4 - infarct due to other identified cause (dissection, hypoperfusion, vasospasm, unusual emboli, venous etc)
5 - unknown cause (only chosen after all investigation)
Pain over an artery is suggestive of what
Artery dissection
Dysphasia is always neurological - true or false
True
Due to the cortex being damaged
It is dysarthria that has a variety of causes
Describe a watershed infarct
Vessel isn’t actually occluded but relative hypoperfusion causes infarcts in the border zones of the vessel’s supply area
E.g. BP drops and is no longer enough to perfuse a narrowed vessel
Describe a venous stroke
Caused by blockage of the venous sinus by a thrombus
Like a DVT in the brain - swells up due to backflow
This leads to infarct but also some leakage of blood products into brain
What is a paradoxical embolic stroke
When a venous clot emoblises but instead of going to the lung it gets to the brain due to a septal defect (ASD)
Presents as any other ischaemic stroke and treatment is the same except you would also involve anticoagulation (standard DVT treatment)
How can illegal drugs cause a stroke
Drugs like cocaine can induce vasospasm and cause a stroke
More common cause in younger people
What is the most common cause of paroxysmal AF
HTN
Always look for it in patients with a HTN history
What is the only difference between a TIA and ischaemic stroke
Only thing is a TIA is transient neurological symptoms without brain damage whereas the stroke isn’t transient and causes damage
How long does a true TIA last
Only a few minutes
If they last hours it is actually a small stroke but due to neuroplasticity the symptoms improve
The risk of stroke is very high following a TIA - true or false
TRUE
You should therefore investigate the person post-TIA and try and reduce their future stroke risk with treatment
This is why they have rapid access TIA clinics now
If someone presents with a stroke, which investigations should you do
General bloods (to get baseline) and specifics (lipids and glucose) ECG - look for AF Carotid doppler Ambulatory monitoring - R test, telemetry etc. To look for AF Echo - if person has atrial dilatation this may indicate AF (done if ambulatory monitoring not picked it up)
What is an R test
R test is a halter monitoring - usually done over 4 days and then data downloaded to look for AF
Used in stroke patients to determine if paroxysmal AF is a cause
What typically causes an arterial clot
Usually due to arterial wall disease like atherosclerotic plaques
How do you treat arterial clots
- Treated with antiplatelets as clots are platelet rich
What other disease processes are typically caused by arterial clots
Ischaemic arterial disease like stroke, MI, ischaemic legs etc
What typically causes an venous clot
- Usually due to imbalance in Virchow (haemostasis, hypercoagulability, endothelial injury)
How do you treat venous clots
- Treated with anticoagulants as formed by coagulation factors
What other disease processes are typically caused by venous clots
Usually causes DVT +/- PE
What is the biggest risk associated with a carotid endarterectomy
Biggest risk is another stroke - the surgery can lead to embolus formation
Which patients are offered a carotid endartectomy
Benefit is seen in patients with a significant carotid stenosis - only done in symptomatic arteries and those with over 70% stenosis
Offered within 2 weeks of the first stroke or TIA
Generally used for the minor strokes or TIA as they have the most to benefit from - can prevent brain damage
Larger strokes will already have a significant disability so benefit does not outweigh the risk
Patient must also be able to discuss and understand the risk
List options for secondary stroke prevention
Antiplatelets Anticoagulants Statins Anti-hypertensives Diabetic management Lifestyle management MDT approach including management of complications
Antiplatelets are used as secondary prevention in which type of stroke
Used for ischaemic only, and only small vessel thrombotic events and atheroembolic large vessel infarcts
Which antiplatelets are used for secondary stroke prevention
Aspirin - may start with a high dose for the 2 week high risk period then drop to 75mg
Clopidogrel
Dipyridamole
Dual therapy can be used - aspirin + clopidogrel 75mg each
Used for small stroke or TIA and those with carotid disease
Anticoagulants are used as secondary prevention in which type of stroke
Used for strokes caused by AF (cardioembolic), paradoxical embolic infarcts and venous infarcts
This is because the clots in these cases are coagulation factor rich
Which anticoagulants are used for secondary stroke prevention
Give warfarin or DOACs (as good as each other)
Patient’s tend to prefer taking DOAC as INR is much more reliable, with warfarin the INR is unreliable and has many more interactions
Why cant heparin be used for secondary stroke prevention
It has a much higher risk of haemorrhagic transformation
Which type of stroke is most common in those on anticoagulant
Still ischaemic!
1/3 will still have another ischaemic stroke despite anti coagulation
If on warfarin and have another ischaemic stroke they can be given thrombolysis - true or false
True - following a rapid INR
Not an option for those on DOACs
What is the biggest risk factor for stroke
Hypertension
How do you prescribe statins for secondary stroke prevention
Start with aggressive treatment as immediate period is highest risk so start on high dose
Statins are used as secondary prevention for which type of stroke
Used for ischaemic stroke with atherosclerotic disease
Early BP control is more important in which type of stroke
Haemorrhagic
Can reduce bleeding and therefore damage
Why would you not want to bring BP down to early in an ischaemic stroke
A slightly raised BP will cause opening of collateral supply which can actually be helpful so don’t want to bring it down too early, unless it is dangerously high (180/110)
How are CT scans used in stroke management
CT is carried out for every ongoing stroke
It is best for picking up acute haemorrhage as this is hard to see on MRI
Therefore used to identify which type of stroke is happening - rule in or out haemorrhage to decide treatment
What is the downside to using CT is stroke
Can miss small infarcts
Cannot differentiate between infarcts and haemorrhage after a few weeks
How does an infarct show up on a CT scan
Takes about 4-5 hours for infarct to show up on CT- done immediately to rule out haemorrhage for treatment
May however see hyper acute signs - may see the clot itself
How are MRI scans used in stroke management
MRI is good for identifying old haemorrhages
Good for checking the type of stroke in TIA
Also better for small vessel disease
List some of the complications of a SAH
Spasm of arteries leading to ischaemia
Hydrocephalus and raised ICP
How can you locate the causative aneurysm after a SAH
In small volume SAH the blood surrounds the cause - e.g. The aneurysm
Would then do a contrast CT to confirm the aneurysm and its location
What are the differentials for someone presenting with headache and confusion
Intracranial haemorrhage Mass (tumour, abscess, hydrocephalus) Infection (meningitis, encephalitis) Venous sinus thrombosis Cerebral infarct (mostly confusion) Migraine (mainly headache)
