stroke Flashcards
stroke
“acute focal neurological deficit resulting from cerebrovascular disease and lasting more than 24hrs or causing earlier death”
Death of brain tissue from hypoxia
- No local cerebral blood flow
3 types of stroke
- Ischaemic stroke (like MI)
- Haemorrhagic stroke (bleed into brain tissue)
- pressure = damage
- TEMPORARY ischaemia
TIA
transient ischaemic attack)
- Rapid loss of function, but regains all neurological components which were lost (within 24hrs)
- Issues in blood vessels
- suggestive of a ‘proper’ stroke in future
accronym to spot a stroke
FAST
Facial drooping
Arm weakness
Speech difficulty
Time
TIA
incidence and effect
Incidence 25% that of stroke
Localised loss of brain function
- Ischaemic event – not haemorrhage
FULL recovery within 24hrs
- Most recover in 30mins
Thought to happen as platelet emboli (from vessels in neck) block blood to brain but are rapidly removed, so blood flow restored before permanent damage incurred
Higher risk of ‘proper’ stroke over 5 years
- 12% in 1yr
- 29% in 5yrs
- 2.4% risk of myocardial infarction
risks for stroke (6)
- HYPERTENSION
- SMOKING
- Alcohol
- ISCHAEMIC HEART DISEASE
- Atrial Fibrillation
- Diabetes Mellitus
diastolic for risk of stroke
if DIASTOLIC >110mm Hg then a x15 risk compared to diastolic <80mm Hg
- Even borderline hypertension has risk
atrial fibrilation linked to stroke
Association with emboli from abnormally contracting atria passing through ventricle into cerebral circulation
% death due to stroke
12%
Infarction 85%
Haemorrhage 10%
Subarachnoid Haemorrhage 5%
Venous thrombosis <1%
commonest cause of adult disability
stroke
incidence and risk of stroke
- Lifetime risk of 1 in 6
- Incidence 2 in 1000 pop/year
- Male > female
- Increasing incidence with age
- 0.5/1000 pop age 50
- 15/1000 pop age 80
causes of ischaemic stroke
- uncertain
- Most of time due to narrowing of vessels and plaques forming – alike MI
causes of haemorrhagic stroke
- Intracranial Bleed
- Aneurysm rupture – weak point which eventually fail
causes of embolic stroke
- Embolism from left side of heart
- Atrial fibrillation
- Heart valve disease
- Recent MI
- Atheroma of cerebral vessels -> changes
- Carotid bifurcation
- Internal carotid artery
- Vertebral artery
how to identift a haemorhhagic stroke on imaging
CT – brain extends to bone around the outside
Radio-opaque mass – blood
- Passed out from blood vessel
- Accumulate in brain
Digital subtraction angiogram
- Small buds (berry aneurysms)
- Weak points for rupture
Can be familial - ask
how to identify an infarction strok on imaging
Harder to see
CT scan – hard to see lesions early after onset
MRI – can see inflammatory taking place around the bleed
3 less common causes of stroke
- Venous thrombosis
- OCP use
- Polycythaemia – high haemoglobin level
- Thrombophilia
- ‘borderzone’ infarction
- Severe hypotension
- Cardiac arrest
- Vasculitis
- Narrow blood vessels into brain, so limitation of oxygen delivery into brain -> strok
e
5 preventative strategies of stroke management
- Reduce risk factors
- Smoking
- Diabetes control
- Control hypertension
- Antiplatelet action
- Anticoagulants
SURGICAL
- Carotid Endarterectomy
- Preventative neurosurgery
- Aneurysm clips, AV malformation correction
antiplatelet drugs for stroke prevention
Aspirin
Dipyridamole
Clopidogrel
secondary prevention only
anticoagulant drug for stroke prevention
embolic risk – AF, LV thrombus occasionally
- warfarin,
- apixaban
surgical prevention for strokes
carotid endarterectomy
preventative neurosurgey
cartoid endartectomy
- Severe stenosis
- Previous TIAs
- <85 years of age
- But 7.5% mortality from surgery
esp when carotid artery involved
-
Large amount of atherosclerosis around carotid furcation
- Either excise (collateral blood supply brain relied on) or remove plaque
important 1st stage in stroke intevestigation
Need to differentiate
- INFARCT
- BLEED
- Subarachnoid Haemorrhage
EARLY information needed to assess treatment options
- Most effective treatment if started early on – minimise tissue loss
imaging options for stroke (3)
CT scan
MRI scan
Digital subtraction angiography (DSA)
CT scan
- rapid, easy access
- good for haemorrhagic
- poor for ischaemic stroke (most common)
MRI Scan
with MR angiography
- Good for both types of stroke
- Difficult to obtain quickly
- Not as easily available in majority of hospitals esp out of hours
- Better at visualising early changes of damage
MRA (MR angiography) is the best investigation for visualising the brain circulation
digital subtraction angiography DSA
- Blood flow in brain
- If MRA not available
MR angiography
- Can see both BV and their location in 3D
subtraction angiography
- Brain tissue removed
- Only see changes in BV
assessing risk factors in stroke investigation
- Carotid ultrasound
- Evidence of carotid sclerosis in carotid artery
- Cardiac ultrasound
- LV thrombus
- ECG changes/abnormalities
- Arrhythmias
- Atrial fibrillation
- Blood pressure
- Diabetes screen
- Thrombophilia screen (young patients)
- higher tendency to form clots
effects of stroke
3 main
- loss of functional brain tissue
- gradual or rapid loss of function
- inflammation in tissue surrounding the infarct/bleed
- not able to determine extent for a few days
Like CVD depend on the size of loss and location of loss
loss of functional tissue due to stroke
Like CVD depend on the size of loss and location of loss
- immediate nerve cell death
- Nerve cell ischaemia in penumbra around infarction
- Will die if not protected – dependent on treatment instituted
- Acute stroke units have evolved (like acute coronary care)
- Specialist treatment familiar with the condition then better outcome more likely
- Acute stroke units have evolved (like acute coronary care)
- Will die if not protected – dependent on treatment instituted
how can a stroke ‘evolve’
Gradual or rapid loss of function
- Stroke may ‘evolve’ over minutes or hours
Inflammation in tissue surrounding the infarct/bleed not able to determine extent for few days
- Recovery of some function with time
3 main complication categories from stroke
- motor function loss
- sensory loss
- cognitive impairment
motor function loss
due to stroke
- Cranial nerve or somatic (opposite side!)
- Autonomic in brainstem lesions
- Dysphonia
- Swallowing
- Aspiration of food & saliva
Pneumonia and death
sensory loss due to stroke
- Cranial nerve or somatic (opposite side!)
- Body perception
- Neglect
- Do not feel it is part of their body
- Phantom limbs
- Neglect
- Body perception
May take while to present all
cognitive impairment in stroke
- Appreciation – special sensation
- Processing
- understanding of information
- Speech and language
- Dysphasia, dyslexia, dysgraphia & dyscalculia
- Memory impairment
- Emotional lability and depression
- Distressing
may take a while to present all
2 phases of stroke management
acute phase
chronic phase
2 aims of acute phase stroke management
- Limit damage
- Manage penumbra effectively
- Reduce future risk
2 aims of chronic phase stroke management
- Rehabilitation
- Reduce future risk
acute phase stroke treatment
- Reduce damage
- Normoglycaemia - hyper/hypo harmful
- Remove haematoma
- Subarachnoid haemorrhage only, or ongoing issues of intra-cranial bleeds
- Prevent future risk
acute phase stroke management techniques to reduce damage
Penumbra region – survivable ischaemia
- Calcium channel blockers (Nimodipine)
Improve blood flow/oxygenation
- Thrombolysis possible within 3hrs (alteplase)
- When ischaemic stroke – requires MRI rapidly after admission
- Maintain perfusion pressure to brain tissue
importance of normoglycaemia in acute phase stroke management
Brain solely dependent on glucose for its energy stores
- If not available pt will have exaggerated damage
Hyper/hypo = harmful
acute phase stroke management - preventing future strokes
Aspirin 300mg daily
Anticoagulation if indicated (delay 2 weeks)
- Atrial Fibrillation
- Left ventricular thrombus
chronic phase stroke treatment
- Nursing and Rehabilitation
- Immobility support
- Prevention of bed sores
- Physiotherapy to prevent contractures
- Immobility support
- Speech and language therapy
- Communications
- Swallowing and eating
- Occupational therapy
dental aspects of stroke (6)
- Impaired mobility & dexterity
- Attendance
- Oral Hygiene
- Communication difficulties
- Dysphonia, dysarthria processing words and language
- cognitive difficulties
- Risk of Cardiac Emergencies
- MI
- Further stroke
- Loss of protective reflexes
- Aspiration
- Managing saliva
- anticholinergic drugs help - block parasym innervation of salivary glands
- Loss of sensory information
- Difficulty in adaption to new oral environment
e. g. new dentures
- Difficulty in adaption to new oral environment
- ‘Stroke pain’
- CNS generated pain perception – reported by pt but not due to any peripheral stimulation
