Neurology - Stroke Flashcards
What is a stroke?
- An acute focal neurological deficit resulting from cerebrovascular disease and lasting more than 24 hours or causing earlier death
What happens during a stroke? (3)
- Death of brain tissue from hypoxia
- No local cerebral blood flow: - infarction of tissue - haemorrhage into the brain tissue
- Temporary ischaemia = TIA (transient ischaemic attack)
There are 2 types of stroke. What are these?
- Ischaemic and haemorrhagic stroke
What is a transient ischaemic attack?
- This happens when there is a rapid loss of function but then a rapid recovery of function so that then thee patient within 24 hours has recovered all of the neurological issues which were lost
- TIA’s represent issues in the blood vessels and are suggestive that the patient has a higher risk of a proper stroke at some point in the future
What is the acronym to help people to remeber what to look for when considering a stroke?
FAST
What does FAST stand for?
- Facial drooping
- Arm weakness
- Speech difficulty
- Time
How is a TIA thought to occur?
- It is thought that these happen because of platelet emboli from the vessels in the neck
- These platelets block the blood flow to the brain tissue causing ischaemia but are then rapidly removed by the circulation and the blood flow is restored before any permanent damage has occurred
- Localised loss of brain function - ischaemic event not haemorrhage
How long does it take for full recovery from a TIA?
- FULL recovery within 24 hours
- Most recover in 30 mins
TIA’s indicate a higher risk of a ‘proper’ stroke over 5 years. What is the % chance of having a stroke 1 year after a TIA?
12%
TIA’s indicate a higher risk of a ‘proper’ stroke over 5 years. What is the % chance of having a stroke 5 year after a TIA?
29%
What is the % risk of an MI if a person has had a TIA?
2.4%
What factors increase the risk of a stroke? (6)
- Hypertension
- Smoking
- Alcohol
- Inchaemic heart disease
- Atrial fibrillation
- Diabetes mellitus
Hypertension is a risk factor for a stroke. If diastolic >110mm Hg then how many more times likely is the patient to have a stroke than if they has diastolic <80mm Hg?
- 15x higher risk
- Even borderline hypertension has a risk
What % of all deaths are from a stroke?
12%
- It is the commonest cause of adult disability
what is the lifetime risk of a person having a stroke?
1 in 6
Does age affect the likelihood of having a stroke?
- Increasing incidence with age
Who is more likely to be at risk of stroke; males or females?
Males
What % of strokes are from infarction?
85%
What % of strokes are from haemorrhage?
10%
What % of strokes are from subarachnoid haemorrhage?
5%
What % of strokes are from venous thrombosis?
<1%
What is the cause of an ishaemic stroke?
- Uncertain
- Most of the time it is due to narrowing of the vessels, plaques forming and ischaemia in the same way as would happen in a cardiac event
One cause of a stroke is an intracranial bleed, how does this occur?
- Aneurysm rupture
One cause of a stroke could be an embolic stroke. How does this occur? (3)
Embolism from left side of heart:
- Atrial fibrillation
- Heart valve disease
- Recent MI
One cause of a stroke could be an atheroma of cerebral vessels. Where does this occur? (3)
- Carotid bifurcation
- Internal carotid artery
- Vertebral artery
What are other less common causes of a stroke? (3)
Venous thrombosis:
- Oral contraceptive use
- Polycythaemia
- Thrombophilia
‘Borderzome’ infarction:
- Severe hypotension
- Cardiac arrest
Vasculitis - these may narrow the blood vessels into the brain and cause limitation of oxygen delivery and thereofre stroke
How can we prevent a stroke? (3)
Reduce risk factors:
- Smoking
- Diabetes control
- Control Hypertension
Antiplatelet action (secondary prevention only)
- Aspirin
- Dipyrisamole
- Clopidogrel
Anticoagulants - embolic risk - AF, LV thrombus
- Warfarin, Apixaban
What kinds of surgery are there to prevent a stroke? (2)
Carotid endarterectomy:
- Severe stenosis
- Previous TIA’s
- <85 years of age
But 7.5% mortality from surgery
Preventative neurosurgery:
- Aneurysm clips, AV malformation correction
Why do we need to investigate the cause of a stroke?
Need to differentiate:
- Infarct
- Bleed
- Subarachnoid haemorrhage
- Early information is needed to assess treatment options
What kinds of imagine might we use to investiage a stroke? (3)
- CT scan
- MRI scan
- Digital Subtraction Angiopathy
What is a positive and a negative for using CT scans to investigate a stroke?
- Rapid, easy access
- Poor for ischaemic stroke (but very good for showing a haemorrhagic stroke
What is a positive and a negative for using MRI scans to investigate a stroke?
- Difficult to obtain quickly
- Better at visualising early changes of damage
What is the best investigation for visualising the brain circulation?
- MRA (MR angiopathy)
IF an MRA is not available what kind of imaging would we use to investiaget a stroke?
- Digital subtraction angiopathy
- This can be used for looking at blood flow in the brain
What can we see in an MR angiopathy?
- Can see both the blood vessels and their location in 3 dimensions
What can we see in a subtraction angiography?
- The brain tissue has been removed and we can only see the changes of the blood vessels
When investigating a stroke we want to assess risk factors. How would we do this? (6)
- carotid ultrasound (looking for evidence of atherosclerosis in the carotid artery)
- Cardiac ultrasound (Left ventricle thrombosis)
- ECG (arrythmias)
- Blood pressure (is the pressure in the vessels too high?)
- Diabetes screen
- Thrombophilia screen (young patients)
What are the possible effects a stroke can have? (3)
Loss of functional brain tissue
- Immediate nerve cell death
- Nerve ischaemia in penumbra around infarction (will die of not protected)
Gradual or rapid loss of function - stroke may ‘evolve’ over minutes or hours
Inflammation in tissue surrounding infarct/bleed
- Recovery of some function with time
Give examples of motor function loss complications of a stroke? (4)
- Cranial nerve or somatic (opposite side)
- Autonomic in brainstem lesions
- Dysphonia
- Swallowing (aspiration of food and saliva -> pneumaonia and death)
What is dynphonia?
- Having an abnormal voice
Give examples of sensory loss complications of a stroke? (3)
- Cranial nerve or somatic (opposite side)
- Body perception:
- Neglect
- Phantom limbs
- The patient might have an arm that they no longer feel belongs to them - they know it is there and they know it is there arm but they feel it is no longer part of their body
- As a result they neglect it and it can result in significant damage
- Similarly the opposite where the patient feels that they have an extra limb can be found
What are cognitive impairment complications of a stroke? (4)
- Appreciation - special sensation
Processing:
- Understanding of information
- Speech and language (dysphasia, dyslexia, dysgraphia & dyscalculia)
- Memory impairment
- Emotional lability and depression
What is dyscalculia?
- This is a specific persistent difficulty in understanding numbers which can lead to a diverse range of difficulties with mathematics
How would we manage a stroke in the acute phase? (2)
- Limit damage
- Reduce further risk
How would we manage stroke in the chronic phase? (2)
- Rehabilitation
- Reduce further risk
Give examples of acute phase treatment to reduce damage? (5)
Penumbra region - survivable ischaemia
- Calcium channel blockers (Nimodipine)
Improve blood flow/oxygenation:
- Thrombolysis possible within 3hrs (alteplase)
- Maintain perfusion pressure to brain tissue
Normoglycaemia - hyper/hypo harmful
- One thing that is very important is the brain glucose level - the brain is solely dependent on glucose for its energy stores and therefore if this is not available the patient will have more of an exaggerated damage from the stroke
Remove haematoma:
- Subarachnoid haemorrhage only
Prevent further risk:
- Aspirin 300mg daily
- Anticoagulation if indicated (delay 2 weeks)
Particularly if patient has a history of:
- Atrial fibrillation
- Left ventricular thrombus
Give examples of nursing anf rehabilitation chronic phase treatment? (3)
Immobility support:
- Prevention of bed sores
- Physiotherapy to prevent contractures
Speech and languahe therapy:
- Communications
- Swallowing and eating
Occupational therapy
What are the dental aspects of a stroke? (6)
Impaired mobility & dexterity:
- Attendance
- Oral hygiene
Communication difficulties:
- Dysphonia, dysarthia
- Cognitive difficulties
Risk of cardiac emergencies
- MI
- Further stroke
Loss of protective reflexes:
- Aspiration
- Managing saliva (alticholinergic drugs help?)
Loss of sensory information:
- Difficulty in adaption to new oral environment e.g. new dentures
‘Stroke pain’
- CNS generated pain perception
- The damage to the brain can change the way in which the brain processes the environment and sometimes the pain is reported by the patient that is essentially generated within the damaged CNS and not due to any peripheral stimulation
