Stroke Flashcards
what is the definition of stroke?
the sudden onset of focal or global neurological symptoms caused by ischemia or hemorrhage and lasting more than 24 hours.
what percentage of strokes are ischaemic and haemorrhagic?
85% are ischaemic strokes
15% haemorrhagic strokes
what is a TIA?
is the term used if the symptoms resolve within 24 hours.
Most TIAs resolve within 1-60 min.
what is a hemorragic stroke?
hemorrhage/blood leaks into brain tissue
what is an ischemic stroke?
clot stops blood supply to an area of the brain
what are the different causes of an ischaemic stroke?
Large artery atherosclerosis (e.g. Carotid) 35%
Cardioembolic (e.g. atrial fibrillation) 25%
Small artery occlusion (Lacune) 25%
Undetermined/Cryptogenic 10-15%
Rare causes <5%
Arterial dissection
Venous sinus thrombosis
what are the different causes of a hemorrhagic stroke?
Primary intracerebral hemorrhage 70%
Secondary hemorrhage 30%
Subarachnoid hemorrhage
Arteriovenous malformation
what are modifiable stroke risk factors?
oestrogenic pills or even HRT prothrombotic
Drugs of abuse like cocaine can be damaging to cerebral blood vessels
Smoking
heart disease, atherothrombosis, risk of subarachnoid haemorrhage,
Bad diet because of high cholesterol and increased risk of atheroma
centripetal obesity
what are non-modifyable risk factors?
Previous stroke
Age
Male
Family history
what is the most important modifyable risk factor?
hypertension
The risk of stroke is related to the level of blood pressure
what does chronic hypertension exacerbate?
atheroma and increases involvement of smaller distal arteries
which arteries experience the most pressure?
Small end arteries coming directly off large arteries experience higher pressure and are at risk of lipohyalinosis
what does lipohyalinosis of small arteries cause?
Lacunar ischaemic stroke
Small vessel haemorrahges
Especially in
Brainstem
Basal ganglia
Subcortical areas
what are smokers at increased risk of?
2x increased risk of cerebral infarction
3x increased risk for sub-arachnoid hemorrhage
how does diabetes affect the likelyhood of suffering from a stroke?
Diabetes mellitus increases the incidence of strokes 3x
how do lipids impact the likelyhood of suffering from a stroke?
The relationship between serum lipids and stroke is established.
Risk related to development of atheroma in blood vessel walls.
A high plasma level of low density lipoprotein (LDL) results in excessive amounts of LDL within the arterial wall.
how does atrial fibrillation increase the risk of a stroke?
Prevalence doubles with age : 9% at 80-90 years
5x increased risk embolic stroke
More severe strokes
Higher mortality and morbidity, longer hospital stays, and lower rates of discharge to patients’ own homes
what has no benefit in patients with AF in reducing chance of ischaemic stroke?
antiplatelets (e.g. Aspirin)
what reduces the risk of ischaemic stroke by 2/3?
Anticoagulants (warfarin and DOACS)
what has less of a risk of causing bleeding than warfarin?
DOACS (e.g. Edoxaban and Apixaban)
what are other risk factors for suffering from a stroke?
Other cardiac causes (recent heart attack, myxoma, PFO).
Oral contraceptives (+ HRT) with a high estrogen content. Progesterone-only OK
Hyper-coagulable states:
- malignancy
- genetic
what is the anterior arterial supply to the brain?
2 x Internal carotid arteries
2 x Anterior Cerebral Artery (ACA)
2 x Middle Cerebral Artery (MCA)
what is the posterior arterial supply to the brain?
2 Vertebral arteries →1 basilar
3 pairs of cerebellar arteries
2 Posterior cerebral arteries (PCA)
what parts of the brain does the carotid system supply?
The carotid system supplies most of the hemispheres and cortical deep white matter
what parts of the brain does the vertebrobasilar system supply?
the vertebro-basilar system supplies the brain stem, cerebellum and occipital lobes
which questions should you ask when making diagnosis of a stroke?
What is the neurological deficit?
Where is the lesion?
What is the lesion?
Why has the lesion occurred?
What are the potential complications and prognosis?
what are functions of the frontal lobe?
High level cognitive functions ie. abstraction, concentration, reasoning
Memory
Control of voluntary eye movement
Motor control of speech (dominant hemisphere)
Motor cortex
Urinary continence
Emotion and personality
what aspect of speech is within the frontal lobe, and what happens if this area is affected?
motor control of speech
Broca’s aphasia or expressive aphasia is when people find it very difficult to find and say the right words, although they probably know exactly what they want to say.
what are functions of the parietal lobe?
Sensory cortex
Sensation (identify modalities of touch, pressure, position)
Awareness of parts of the body
Spatial orientation and visuospatial information (non dominant hemisphere)
Ability to perform learned motor tasks (dominant)
what are functions of the temporal lobe?
Primary auditory receptive area
Comprehension of speech (dominant) – Wernicke’s
Visual, auditory and olfactory perception
Important role in learning, memory and emotional affect
what aspect of speech is within the temporal lobe, and what happens if this area is affected?
Wernicke’s aphasia – usually left hemisphere. Deficit in language comprehension. Can speak fluently but has semantic errors and may sound nonsensical/jargon
what is the homonculus?
The sensory homunculus is a topographic representation of the sensory distribution of the body found in the cerebral cortex. This topograph usually has body parts illustrated along the surface of the postcentral and precentral gyrus of the parietal lobe.
what would infarct of the anterior cerebral artery cause weakness of, (supplies part of the precentral gyrus)?
leg>arm weakness
what would infarct of the middle cerebral artery cause weakness of, (supplies part of the precentral gyrus)?
face and arm> leg weakness
what will a small stroke in deep white matter/corticospinal tract result in?
A small stroke here
(or there)
will result in a major deficit as the fibres are packed close together
what function is controlled by the cerebellum?
Balance and coordination
what makes up the brainstem?
Midbrain, pons and medulla
which cranial nerves arise from the brainstem?
10 of 12 cranial nerves arise in brainstem (ipsilateral signs)
what would a stroke in brainstem result in?
Contralateral hemiparesis due to crossing of cortical tracts in lower medulla
Some major functions: eye movement, breathing, swallowing, heart beat, consciousness
what are functions of occipital lobe?
Primary visual cortex
Visual perception
Involuntary smooth eye movement
what are clinical presentations of stroke?
Motor (clumsy or weak limb)
Sensory (loss of feeling)
Speech: Dysarthria/Dysphasia
Neglect / visuospatial problems
Vision: loss in one eye (amaurosis fugax) or hemianopia
Gaze palsy
Ataxia/ vertigo / incoordination / nystagmus
do symptoms of stroke have a rapid onset?
yes
what do symptoms depend on?
which part of the brain is affected
how can strokes be classified?
according to Oxford Community Stroke Project Classification (OCSP)
what are the four different clinical classifications of stroke?
Total Anterior Circulation Stroke (TACS)
Partial Anterior Circulation Stroke (PACS)
Lacunar Stroke (LACS)
Posterior Circulation Stroke (POCS)
describe OCSP classification of LACS?
small vessel
anterior
+/- weakness (>2/3 face arm leg)
+/- numbness (>2/3 face arm leg)
- hemianopia/dysphagia/neglect
- cerebellar signs
describe OCSP classification of PACS?
large / partial vessel
anterior
+/- weakness (>2/3 face arm leg)
+/- numbness (>2/3 face arm leg)
1 of hemianopia/dysphagia/neglect
- cerebellar signs
describe OCSP classification of TACS?
large / total vessel
anterior
+/- weakness (>2/3 face arm leg)
+/- numbness (>2/3 face arm leg)
2 of hemianopia/dysphagia/neglect (must have hemianopia)
- cerebellar signs
describe OCSP classification of POCS?
either large or small vessel
posterior
+/- weakness (>2/3 face arm leg)
+/- numbness (>2/3 face arm leg)
+/-hemianopia/dysphagia/neglect (must have hemianopia)
+ cerebellar signs
what would a patient present with following a stroke affecting right hemisphere?
Left hemiplegia, homonymous hemianopia
Neglect syndromes (agnosias)
Visual agnosia
Sensory agnosia
Anosagnosia (denial of hemiplegia)
Prosopagnosia (failure to recognise faces)
describe the criteria for a TACS?
Main artery to one hemisphere
“Full house” of effects 3 of 3:
Complete hemiparesis/numbness
Loss of vision on one side (hemianopia)
Loss of awareness on one side (inattention) non-dominant
or
Dysphasia dominant
TACS is often due to blocked Carotid or Middle cerebral artery
describe criteria for a PACS?
Branch of main artery
In-between LACS and TACS
2 of 3 TACS criteria
or
One higher cortical deficit:
Inattention
Or dysphasia
or
Monoparesis
describe the criteria for a LACS?
Small “perforating” artery
Movement and sensation pathways
Weakness/numbness of:
Face + arm + leg
Or Face + arm
Or Arm + leg
May have dysarthria
Ataxic hemiparesis
No affect on higher function
Will not have dysphasia, inattention or hemianopia
describe the criteria for a POCS?
Any posterior artery
Combination of symptoms including:
Loss of balance/coordination
Vertigo
Double vision
Dysarthria
Visual loss (hemianopia)
describe the criteria for a basilar artery occlusion?
Ischaemia in pons
Predominantly motor/oculomotor signs/symptoms
Bilateral but asymmetrical
Alteration in level of consciousness common
– may progress over 12-24hours
May present as reduced responsiveness
?cause requiring critical care
what is the mortality and reccurance rate of TACS at 12 months?
mortality - 60%
recurrance rate - 6%
what is the mortality and reccurance rate of PACS at 12 months?
16%
17%
what is the mortality and reccurance rate of LACS at 12 months?
11%
9%
what is the mortality and reccurance rate of POCS at 12 months?
19%
20%
what conditions can mimic symptoms of a stroke?
Seizures
Syncope (hypotension)
Sugar (hypo or hyper)
Sepsis (+previous stroke)
Severe migraine
Space occupying lesions
Si-chological (Functional)
And
Vestibular disorders
Demyelination
Transient global amnesia
Mononeuropathy
what are positive symptoms for a stroke?
excess CNS neurone electrical discharges
visual (eg, flashing lights, zigzags, shapes, lines, objects)
somatosensory (eg, pain, paraesthesia)
motor (eg, jerking limb movements)
what are negative symptoms of a stroke?
Loss or reduction of CNS neurone function
Loss of vision
Loss of sensation
Loss of limb power
what do >20% of patients with suspected TIA have?
migraine aura - most common mimic
what is a migraine aura?
Migraine aura symptoms include temporary visual or other disturbances that usually strike before other migraine symptoms — such as intense head pain, nausea, and sensitivity to light and sound. Migraine aura usually occurs within an hour before head pain begins and generally lasts less than 60 minutes.
what symptoms occur alongside a migraine aura?
Visual disturbances
scintillating scotomata
geometric (especially zigzag) patterns
positive symptoms (like a kaleidoscope, running water etc)
Can include sensory, motor or speech disturbance
Headache onset can be >1hour after the end of the aura or no headache
who does functional/anxiety disorder most commonly affect?
Younger
More common in women
No conventional risk factors
what is hoovers sign?
Hoover’s sign1 is a manoeuvre aimed to separate organic from non-organic paresis of the leg. The sign relies on the principle of synergistic contraction. Involuntary extension of the “paralysed” leg occurs when flexing the contralateral leg against resistance
what are the signs and symptoms of acute vestibular syndrome?
Common, onset can be acute
Can be very disabling
‘True vertigo’ vs unsteadiness vs dizziness
Nystagmus – unidirectional, increases in intensity when patient looks in direction of fast phase
Vomiting
Even an expert taking a careful history may remain uncertain
MRI can be helpful
what investigations are done for a stroke in all patients?
Routine blood tests (FBC, glucose, lipids, ESR…)
CT or MRI head scan (infarct vs. hemorrhage)
ECG + Holter (?AF, LVH)
Carotid doppler ultrasound (?stenosis)
what investigations are done for stroke in some patients?
Echocardiogram (valves, ASD, VSD, PFO)
Cerebral angiogram/venogram (vasculitis?)
Hyper-coaguable blood screen
what should acute ischaemic stroke therapies do?
Restore blood supply.
Prevent extension of ischemic damage.
Protect vulnerable brain tissue.
what are different stroke treatments offered?
aspirin
thrombolysis
thrombectomy
what are compoenents of a stroke unit
Clinical staff
Stroke nurses
Physiotherapists
Speech and Language therapists
Occupational therapists
Dietician
Psychologist
Orthoptist
what is the strict criteria dor use of TPA?
< 4.5 hours from symptom onset.
Disabling neurological deficit.
Symptoms present > 60 minutes.
Consent obtained.
what is exclusion criteria for IV TPA?
Anything that increases the possibility of hemorrhage:
blood on CT scan
recent surgery
recent episodes of bleeding
coagulation problems
BP >185 systolic or >110 diastolic
Glucose <2.8 or > 22mmol/L
what is effective treatment in symptomatic internal carotid artery stenosis?
Carotid endarterectomy
what is secondary preventatives for stroke?
Anti-hypertensives >25%
Anti-platelets 25%
Lipid lowering agents 25%
Warfarin for AF 66%
Carotid endarterectomy NNT of 3
(Absolute reduction of 30%)
