Stroke Flashcards
What is Stroke?
- Acute focal neurological deficit resulting from cerebrovascular disease and lasting more than 24hrs or causing earlier death
What happens during a stroke?
- Death of brain tissue from hypoxia
- No local cerebral blood flow
- Leads to infarction of tissue
- Haemorrhage into brain tissue
What are the types of stroke?
- Ischaemic stroke
- Haemorrhagic stroke
- Transient Ischaemic attack (TIA)
What is a Transient Ischaemic attack?
- Mini stroke (25% that of stroke)
- Happens when rapid loss of localised brain function but also rapid recovery of function
- Is Ischaemic event and not haemorrhage
- Patient within 24hrs recovers all neurological function lost (most recover within 30mins)
- Thought it is because platelet emboli in blood vessels in neck block blood flow to brain tissue causing ischaemia, also rapid removal so no permanent damage occurs
- Higher risk of stroke in future (12
What acronym is used to help people recognise a stroke?
FAST
- Facial drooping
- Arm weakness
- Speech difficulty
- Time
What are Risk factors for stroke?
- Hypertension (if DIASTOLIC >110mm Hg then at x15 risk compared to <80mm Hg)
- Smoking
- Alcohol
- Ischaemic heart disease
- Atrial fibrillation
- Diabetes Mellitus
What is the incidence of stroke?
- 12% of all deaths
- Commonest cause of adult disability
- Infarction 85%
- Haemorrhage 10%
- Subarachnoid haemorrhage 5%
- Venous thrombosis <1%
- Male > Female
- Increasing incidence with age
What are causes of Ischaemic stroke?
- Mostly uncertain
- Narrowing of blood vessels, plaque forming and ischaemia same as cardiac event
What are the causes of Haemorrhagic stroke?
- Intracranial bleed via aneurysm rupture
What are the causes of Embolic stroke?
- Can be from an embolism from left side of heart caused by Atrial fibrillation, Heart valve disease or Recent MI
- Can be from atheroma of cerebral vessels at carotid bifurcation, or internal carotid artery or Vertebral artery
What are less common causes of stroke?
Venous thrombosis
- Oral contraceptive use
- Polycythaemia
- Thrombophilia
Borderzone infarction
- Severe hypertension
- Cardiac arrest
Vasculitis (inflammation of the blood vessels causing them to be swollen and narrow - limits oxygen delivery and stroke)
How can stroke be prevented?
Reduce risk factors
- Smoking
- Diabetes control
- Control hypertension
Antiplatelet action (secondary action only)
- Aspirin
- Dipyridamole
- Clopidogrel
Anticoagulants like Warfarin and Apixaban
- Embolic risk
How can stroke be prevented via cardiac surgery?
Carotid Endarterectomy can be performed
- Surgeon makes cut along neck and open carotid artery, remove plaque deposits clogging artery. Repair artery with stitches or a patch made with vein or artificial material
- For people with Severe stenosis (Prevents aortic valves opening and closing properly)
- Or who have had previous TIA’s
- Or <85 years old
- 7.5% mortality from surgery
How can stoke be prevented by neurosurgery?
- Aneurysms clips
- AV malformation correction (small incision via AVM and seal surrounding arteries and veins so don’t bleed and remove AVM)
What to do when investigating a stroke?
- Need to differentiate between Infarction/ Bleed/ Subarachnoid haemorrhage
- Early info needed to assess best treatment options
- Treatment needs to be started almost immediately to prevent loss of tissue
What imaging can be used to investigate a stoke?
CT Scan
- Rapid, easy access
- But poor for showing Ischaemic stroke (most common)
MRI Scan
- Shows both types
- Hard to obtain quickly
- better at visualising early changes of damage
- MRA (MR angiography) best investigation for visualising brain circulation
Digital Subtraction angiography (DSA)
- Shows Blood flow in brain not brain tissues
- Use if MRA not available
How to assess risk factors when investigating stroke?
- Carotid ultrasound
- Cardiac ultrasound in case thrombus forming in LV
- ECG to check arrhythmias and atrial fibrillation
- Blood pressure
- Diabetes screen
- Thrombophilia screen esp in young patient as they have tendency to form clots more than usual
What are the effects of stroke?
Loss of functional brain tissue
- Immediate nerve cell death
- Nerve cell ischaemia in penumbra around infarction and will die if not protected by specialist treatment
Gradual or rapid loss of function
- Stroke may evolve over minutes or hours
Inflammation in tissue surrounding infarct/bleed
- As inflammation settles some recovery can be made
What are the complications of stroke?
Motor function loss
- Dysphonia (hoarseness)
- Swallowing (food cannot be kept out of airway so aspiration of food and saliva is risk and may lead to pneumonia and death
- Cranial nerve or somatic (opposite side) loss
- Autonomic in brainstem lesions
Sensory loss
- Cranial nerve or somatic loss
- Body perception (phantom limbs experience and can lead to neglect of that body part) - May not be immediate
Cognitive impairment
- Appreciation (special sensation)
- Processing like understanding of of info and speech and language (dysphasia, dyslexia, dysgraphia, dyscalculia)
- Memory impairment
- Emotional lability and depression
How do you manage stroke?
Acute phase
- Vital to limit damage and reduce future risk
Chronic phase
- Rehabilitation and reduce future risk
What is included in acute phase treatments?
Reduce damage
- Aim to reduce the penumbra region damage by calcium channel blockers such as Nimodipine
Improve blood flow/oxygenation
- Thrombolysis possible within 3hrs (alteplase)
- Maintain perfusion pressure to brain tissue
Normoglycaemia
- Maintain brains normal glucose levels as hyper/hypo is harmful
Remove haematoma
- Can be done mostly in subarachnoid haemorrhage
Prevent future risk
- Aspirin 300mg daily
- Anticoagulation if indicated if patient has history of atrial fibrillation or LV thrombus
What is included in Chronic Phase treatment?
Nursing and Rehabilitation
- Immobility support for prevention of bed sores and physiotherapy to prevent contractures
Speech and language therapy
- Communication
- Swallowing and eating
Occupational therapy
What are the dental aspects of stroke?
Impaired mobility and dexterity
- Attendance affected
- Oral hygiene affected
Communication difficulties
- Dysphonia, Dysarthria
- Cognitive difficulties
Risk of cardiac emergencies
- MI
- Further stroke
Loss of protective reflexes
- Aspiration
- Managing saliva (Anticholinergic drugs may help)
Loss of sensory info
- Difficulty in adaptation to new oral environment like dentures
‘Stroke pain’
- CNS generated pain perception, may report pain that isn’t actually present
