Stroke Flashcards
Define a stroke
Stroke is the ‘umbrella’ term used to describe an event where the blood supply to part of the brain is disrupted.
Explain the two types of stroke.
Ischaemia (infarction)- where the blood supply to part of the brain is cut off due to a clot.
Haemorrhage - where the blood supply is disrupted in the brain due to a weakened blood vessel bursting.
What type of stroke is more common?
85% of strokes are ischaemic
10% are due to primary haemorrhage (IntraCerebral Haemorrhage)
5% due to subarachnoid haemorrhage
Ischaemic strokes are 7-8 times more common
In relation to ischaemic strokes, will all patients experience the same symptoms?
No, patient symptoms due to ischemia result as a consequence of the blood vessels in a particular area of the brain that is affected.
Therefore Doctors can use their understanding of arterial anatomy and the brain territories supplied by the cerebral arteries to predict the blood vessels that have been affected and the consequence that this will have on the patient.
When do stroke symptoms occur?
When the oxygen and nutrient supply to the brain is cut off.
State the three arteries that supply each of the cerebral hemispheres.
Anterior cerebral artery - ACA
Middle cerebral artery - MCA
Posterior cerebral artery - PCA
Describe where the anterior cerebral artery supplies.
Supplies the medial portion of the frontal and parietal lobes and anterior portion of the basal ganglia.
Describe where the middle cerebral artery supplies.
Supplies the lateral portions of the frontal and parietal lobes and the lateral portions of the temporal lobes.
It is the dominant source of vascular supply to the hemispheres.
Describe where the posterior cerebral artery supplies.
Supplies the thalamus, brainstem, posterior and medial, temporal and occipital lobes.
Which side of the brain controls movement on each side of the body?
The nerves that originate in the right hemisphere are responsible for the motor control of the left side of the body.
The nerves originating in the left hemisphere are responsible for the motor control of the right side of the body.
State the four different areas of the cerebrum and what are they responsible for?
For each cerebral hemisphere there are different areas which control planned movement (on that correlated side of the body), thinking, feelings, emotions, memory
The fourdifferent areas are:
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Each lobe is responsible for different skills.
What are some of the functions of the frontal lobe?
Speaking
Planning
Problem solving
Starting some movements
Processing emotions
Part of your personality and character
What are some of the functions of the parietal lobe?
Touch
Temperature
Pressure
Pain
Reception and evaluation
Object recognition
What are some of the functions of the temporal lobe?
Evaluating auditory (processing language)
Olfactory input
Important role in memory, thought and judgement
What are some of the functions of the occipital lobe?
Reception and integration of visual input (colour, shape and distance)
Describe what is an transient ischaemic attack.
The acute loss of focal cerebral or ocular function with symptoms (neurological deficit) lasting less than 24 hours’.
When do the symptoms associated with a TIA resolve?
Usually resolve within minutes or a few hours at most
Why should TIAs still be treated as a medical emergency?
Often a warning sign that you are at risk of having a full stroke in the near future .
Describe the risk of having a full stroke after a TIA?
Very high risk within one month and up to a year afterwards
What happens during a primary haemorrhagic stroke?
When a blood vessel bleeds into the deep
cerebral tissue of the brain, this is known as a Intracerebral Haemorrhage
What happens during a subarachnoid haemorrhage?
Occurs when a blood vessel on the surface of the brain ruptures and bleeds into the subarachnoid space
Under what circumstances does a haemorrhagic stroke occur?
Occurs when there is weakened or abnormal blood vessels.
May also be caused when the blood vessels are under pressure due to brain tumours, inflammation or after trauma.
Is stroke a leading cause of death?
It is the second leading cause of death worldwide.
Is it a leading cause of death in the UK?
Fourth leading cause in the UK
How many strokes occur each year in the UK?
There are more than 100,000 strokes in the UK each year
What is the prevalence of strokes in the UK?
Around 1 in 6 men and 1 in 5 women will have a stroke in their lifetime
Does risk of stroke increase with age?
Incidence of stroke increases with age, although people are having strokes at earlier ages than in the past
What is the relationship between ethnicity and stroke in the UK?
Black people are almost twice as likely to have a stroke as white
people.
Over the past 20 years, stroke incidence has decreased by 40% for white people in London but has not decreased for black people
Which ethnicities are more prone to having strokes earlier in their lifetimes and why?
On average, people of black African, black Caribbean and South Asian descent in the UK have strokes earlier in their lives – potentially due to increased risk of hypertension and diabetes.
What are two of the most common consequences of having a stroke? How many people suffer from them?
1/3 of people suffer depression after having a stroke
2/3 of stroke survivors leave hospital with some form of disability
How many stroke survivors are there in the UK?
1.3 million
What is the cost of strokes on society?
£26 million a year
What is the prevalence of TIAs?
50 per 100,000 people experience a TIA for the first time each year
What is the prevalence of the subarachinoid haemorrhages?
6-12 people per 100, 000 of population per year
What are the risk factors of developing an ischaemic stroke?
Family history of a stroke/TIA
Previous stroke or TIA
Hypertension
Diabetes
Smoking
Excess alcohol
Illicit drug use
Inactivity
Migraine
Increased age
Males
Cardiac disease
Dysplipidemia
Ethnicity
Hypercoagulabel status
Carotid artery stenosis
What are the cardiac diseases that are a risk factor for ischaemic strokes?
Atrial fibrillation
valvular disease
Heart failure
Mitral stenosis
Structural abnormalities
Atrial and ventricular enlargement
What are some of the risk factors for haemorrhagic strokes?
Hypertension
Males
Smoking
Excessive alcohol/illicit drug use
Diabetes
Head injury
Use of anticoagulants
State the known causes of Ischaemic strokes
Atherosclerosis
Arterial stenosis
Cardiac or carotid emboli
Hypercoagulabel status
Arterial dissections
Vasoconstriction associated with substance misuse
What are the causes of an intracerebral haemorrhage?
High blood pressure
Vessel abnormalities
Bleeding disorders
Vasculitis
Amyloid angiopathy
Arteriovenous malformations
What are the causes of a subarachinoid haemorrhage?
Arteriovenous malformations
Aneurysm (congenital or due to chronic high BP)
Explain what type of stroke is associated with atrial fibrillation?
Ischaemic stroke, specifically ischaemic strokes caused by the formation of arterial emboli.
Arterial emboli ischaemic strokes are defined by blood clots (thrombus) that accumulate away from the brain. The thrombus or a fragment of the thrombus becomes dislodged and travels to the brain causing a blood clot.
When the thrombus formation originates in the heart and then this or part of it travels to the brain, this is known as a cardioembolic stroke. Atrial fibrillation is a heart condition known to cause cardioembolic strokes.
(formation of thrombus in the heart)
What percentage of people presenting with a stroke are in atrial fibrillation?
25%
Describe how atrial fibrillation leads to increased risk of stroke.
Atrial fibrillation is the most common sustained cardiac arrhythmia resulting in haphazard (generally rapid) atrial contraction.
In a normal heart beat the atria
communicate with the ventricles (via the atrioventricular node) to ensure
subsequent, sequential contraction to eject blood from the heart. However, in AF only a few of the pulses pass through to the ventricles leading to irregular and incomplete (varied force) contraction.
Both Turbulent flow and blood stasis in the heart increases the risk of emboli formation which increase the risk of stroke.
If a stroke is caused by atrial fibrillation what type of stroke can it be caused?
Cardioembolic stroke
Aside from atrial fibrillation which other cardiac complication is associated with strokes?
Atherosclerosis which also leads to thrombi formation.
What are the two pathophysiological causes of an ischaemic stroke?
Arterial thrombi
Arterial emboli
What is the differences between arterial thrombi and arterial emboli?
Arterial thrombi - occurs when a thrombi forms in one of the vessels supplying the brain with oxygen and nutrients, this often occurs due to a ruptured atherosclerotic plaque which initiates the clot formation.
Arterial emboli- This type of stroke occurs when a thrombus or other debris forms/accumulates at a site away from the brain. Part of the thrombus can become dislodged and it can travel up to the brain.
Where is the extra and intra cranial vasculature in the brain?
Extra cranial blood vessels are outside of the skull
Intracranial blood vessels are within the skull or are at the base of the skull
Do clots occur in the extra or intra cranial vasculature and what is the outcome?
Both and in both cases parts of the brain are starved of oxygen and nutrients causing the central core cells to die.
Define infarct.
A small localized area of dead tissue resulting from failure of blood supply
What is the clinical significance of the penumbra in treatment of a stroke?
Penumbra is the area surrounding an ischemic event such as thrombotic or embolic stroke. Immediately following the stroke, blood flow and therefore oxygen transport is reduced locally, leading to hypoxia of the cells near the location of the original insult. This can lead to hypoxic cell death (infarction) and amplify the original damage from the ischemia; however, the penumbra area may remain viable for several hours after an ischemic event due to the collateral arteries that supply the penumbral zone.
Therefore as the penumbra is reversibly injured brain tissue- trying to restore blood flow and hence supply of oxygen throughout the brain, attempts to restore as much of the tissue as possible.
What happens within the ischaemic area during a stroke?
As blood flow in the brain is restricted hypoxia occurs and leads to neuronal damage.
There is a fall in ATP with release of glutamate, which opens calcium channels with release of free radicals.
These alterations lead to inflammatory damage, necrosis and apoptotic cell death
Describe the relationship between the size of the emboli and the blood vessels affected?
Larger emboli will occlude larger blood vessels which are responsible for carrying a supply of blood and hence oxygen and nutrients to a larger proportion of the brain and therefore will have larger consequences on brain function as a larger portion of the brain is being starved of oxygen.
Smaller emboli will occlude smaller blood vessels and therefore have a smaller impact on portion of brain starved of oxygen, resulting in a smaller impact on brain function.
Is it possible with a small emboli to have minimal effects on brain function?
Yes, especially if the emboli blocks a blood vessel but there are other blood vessels also serving that area (collateral circulation) , meaning that some supply is still achieved.
How do patients experience different effects from having a stroke?
The position of the thrombus or eventual position of the embolus will dictate the
types of brain functions that are affected - essentially which blood vessel in the brain are blocked serving which areas of the brain and the functions those areas are responsible for.
What complication is likely to arise following a ischaemic stroke?
Up to 6% of ischaemic stroke patients will sustain a symptomatic haemorrhagic transformation (will also suffer a brain haemorrhage) and more will have asymptomatic bleeding.
What types of stroke are more commonly associated with haemorrhagic transformation?
Following a cardioemolic stroke or those with a larger infarct size (area of dead tissue following failure of blood supply)
How does the pathophysiology of a TIA compare with ischemic stroke?
Same process but resolves quickly meaning that infarction does not occur
How is flow restored in TIA?
Autolysis (self-digestion)
What does the severity of clinical neurological impairment after arterial occlusion depend on?
The degree of obstruction
Area and function of tissue supplied
Time the thrombus obstructs the vessel
The ability of the collateral circulation
Explain the pathophysiology of intracerebral haemorrhage.
Weakened arteries burst and release blood into the surrounding brain tissue.
This increases the pressure in that area of the brain and causes the release of
excitatory amino acids and the infiltration of immune cells.
In addition to the effect of the released blood on the brain tissue, the usual area
served by the damaged vessel has its blood supply compromised leading to
increased damage to brain tissue.
What are some of the complications associated with an intracerebral haemorrhage?
Haemotoma formation
Increase intracranial pressure (ICP),
Hydrocephalus
Compression – can damage the surrounding brain area
Explain the pathophysiology of subarachinoid haemorrhage.
An artery on or near the surface of the brain bursts and releases blood into the
subarachnoid space between the brain and the skull.
SAH results in elevated intracranial pressure and impairs cerebral
autoregulation. These effects can occur in combination with acute
vasoconstriction, microvascular platelet aggregation and loss of microvascular
perfusion, resulting in a reduction in blood flow and cerebral ischaemia
What are some of the complications arising from a subarachinoid haemorrhage?
Haematoma formation
Hydrocephalus
Compression
What do the clinical features arising from a stroke depend on?
Location of disrupted blood flow (which blood vessels in which area of the brain)
Extent of damage
Patient’s underlying health
What does HANDBAG stand for in recognising focal ischaemic stroke symptoms?
Hemisensory deficit- loss of sensation on one side of the body
Ataxia- – failure of muscular coordination or irregularity of muscular action
Nystagmus – rhythmic oscillating motions of the eyes more usually horizontal
Dysarthria – difficulty in articulating words due to difficulty in coordinating
the muscles used in speech
Blindness either monocular or binocular blindness - affecting the sight in one or both eyes
Aphasia – partial or total loss of the ability to communicate verbally or using
written words
Gazing – looking steadily in one direction for a period of time
Aside from HANDBAG what are the other focal symptoms of an ischaemic stroke?
Weakness or paresis
Unilateral facial droop
Blurred vision
Vertigo
Double vision
Dysphagia
Decreased consciousness
Confusion
Severe headache
Where does weakness or paresis occur?
Can affect a single extremity (monoparesis), one half of the body (hemiparesis) or (rarely) all four extremities (quadraparesis)
What are some of the complications associated with aphasia?
People may experience difficulty in reading, writing and speaking, recognising objects or understanding. People may use the wrong word or struggle stringing a sentence together, wrong sounds in a word.
What symptoms are suggestive of an increase in intracranial pressure?
Nausea, vomiting, sudden onset headache and altered level of consciousness
If symptoms of an increase in intracranial pressure did occur what type of stroke are they likely to be experiencing?
Large ischaemic stroke or haemorrhagic stroke
Do seizures commonly occur alongside strokes?
Seizures are more common in haemorrhagic stroke occurring in up to 28% of patients either at the onset or within 24 hours of the event.
From the symptoms alone can you determine a haemorrhagic or ischaemic stroke?
No, not from the symptoms alone
What are some of the symptoms that suggest a disturbance of the physiological homeostasis?
Increase in temperature
Increase in blood pressure
Increase in blood glucose
Hypoxia
Larger the infarction, the greater the extent
What is the purpose of FAST?
Provides a memorable way of identifying the most common signs of a stroke and emphasises the importance of acting quickly by calling 999 and is the tool of choice for pre-hospital clinicians such as GP and paramedics.
What does FAST stand for?
Face weakness: Can the person smile? Has their mouth or eye drooped?
Arm weakness: Can the person raise both arms?
Speech problems: Can the person speak clearly and understand what you say?
Time to call 999: if you see any of these signs.
What are the limitations of FAST?
Doesn’t cover all of the stroke symptoms are therefore a stroke can’t be ruled out if patients not defined as having those symptoms but others that do align with a stroke (visual disturbances).
A patient has a positive FAST or negative FAST but a stroke is strongly suspected what should you do?
Transfer to a a hospital with a specialist acute stroke unit. As there is strong evidence to suggest that a specialist unit to deliver effective acute treatment that
reduces long term brain damage and disability if given within a few hours (better patient outcomes).
What is a CRUCIAL intervention that must be made regarding the administration of a stroke patient’s medication?
Patient must be assumed NIL BY MOUTH
This means that:
No fluid, food or medication should be given orally until this has occurred
When is the swallowing status of a stroke patient determined?
The screening of a patient’s swallow is made within 4 hours of arrival usually by a Speech and Language team. This is known as having a SALT assessment.
Until a safe swallowing method is established what pharmaceutical interventions should be considered?
Feeding by a nasogastric tube within 24 hours
Considered for alternative fluids (intracranial pressure considerations- reduced fluids)
Referred to a dietician for assessment, advice and monitoring
Have a comprehensive specialist assessment of their swallow
Receive hydration, nutrition and medication by alternative means
Be referred to a pharmacist to review the formulation and administration of
medicines.
What are some of the scans used with a suspected stroke and what is the purpose of the scan?
Brain imaging must be done via CT scan
CT scans are the most cost-effective strategy and imaging enables
identification of the presence of a haemorrhage or ischaemic infarct, the extent of the cerebral damage (core and penumbra) and aetiology as this will dictate
the treatment.
Are these scans limited to stroke patients?
No these scans should be completed for anybody presenting with an acute onset of neurological syndrome with persisting
symptoms requires a full diagnosis to differentiate between an acute
cerebrovascular cause and other causes.
When should a CT scan be done for a suspected stroke patient?
Within 1 hour of arrival at hospital as it dictates treatment.
What is the Carotid doppler?
This is a non-invasive test using sound waves to measure the flow of blood
through the carotid arteries which supply blood to the brain. It is used to identify
narrowing of these arteries.
State the additional tests that are completed with a suspected stroke patient and the purpose of them?
Blood glucose
Clotting
ECG
Fasting lipids
Blood culture
Full blood count
Urea and electrolytes
Helps to determine, exclude and diagnose strokes.
What is the purpose of taking a patient’s blood glucose?
Determine whether symptoms are related to a hypoglycaemic episode as they can be similar
What is the purpose of taking a patient’s clotting factors?
Clotting factors such as APTT, PT and INR determine whether there is any underlying bleed risk which may be a causative factor in the presentation or dictate
treatment.
What is the purpose of taking a patient’s ECG?
Detect any cardiac arrythmia which may have been causative of the stroke
What is the purpose of taking a patient’s fasting lipids?
Determine the likelihood of atherosclerotic plaque rupture
What is the purpose of taking a patient’s full blood culture?
Determine an infective causative agent
What is the purpose of taking a patient’s full blood count?
May reveal a cause for the stroke, (i.e. thrombocytosis, polycythaemia, leukaemia, thrombocytopenia).
What is the purpose of taking a patient’s urea and electrolytes?
Baseline study to determine whether there are any other likely causes of the symptoms (i.e. hyponatraemia) or evidence of
concurrent illness (i.e. renal impairment).
What scale is used to determine a patient’s level of consciousness?
Glasgow Coma scale
What is the purpose of the physical examinations in a suspected stroke patient?
To determine the area of the brain affected and the extent of damage
What are some of the physical examinations that should be completed?
Cranial nerve examination
Motor function examination
Sensory function
Cerebellar function
Gait
Deep tendon reflex
Language (expressive and receptive capabilities)
Lumbar puncture
What is the purpose of completing a lumbar puncture in a potential stroke patient?
To rule out meningitis or subarachnoid haemorrhage
When is a CT scan used in suspected TIA patients?
Only when there is clinical suspicion that it may not be a TIA (such as symptoms or history does not align).
-Area of the brain affected is unknown
-Cause of the symptoms is unknown (atypical presentation)
-Detect haemorrhage
-Or if these factors influence treatment (such as if treatment is dependent on the area affected).
When may it be likely that a patient has experienced a haemorrhage?
If they are on anti-coagulation and therefore should be scanned immediately to locate the site of bleeding
What is the purpose of acute treatment of a stroke?
To maintain/improve vascular perfusion of the brain
To prevent further deterioration of neurological symptoms by
preventing the advancement of the penumbra