What is a stroke?
Syndrome of rapid onset of neurological deficit caused by focal, cerebral, spinal or retinal infarction. Characterised by rapidly developing signs of focal or global disturbance of cerebral functions, lasting for more than 24h or leading to death.
What does the external carotid artery supplie?
Everything in the head and neck apart from the brain
What does the anterior cerebral artery supply?
Supplies motor cortex and top of brain
What does the middle cerebral artery supply?
Supplies the majority of the outer surface of brain
What does the posterior cerebral artery supply?
Supplies peripheral vision
What is the most common type of stroke?
Ischaemic stroke (80%)
What is the pathophysiology of an ischemic stroke?
Either from:
- Endothelial damage leading to atherosclerosis and occlusion of the vessel - usually happens in branching points of vessels e.g internal carotid and middle cerebral artery.
- Embolism - typically occurring in a vessel with a smaller diameter.
Give a cause of an embolism in the brain?
Stagnant blood due to atrial fibrillation or heart attack - can lead to a clot in the right atria which can then travel to the brain.
What are the risk factors for ischaemic stroke?
- Age (risk increases with age)
- Race
- Hypertension
- Past TIA
- Smoking
- Diabetes mellitus
- Increasing age
- Heart disease (valvular, ischaemic)
- Alcohol
- Polycythaemia, thrombophilia (blood more likely to clot)
- AF (stasis of blood in poorly contracting artia = thrombus formation
- Hypercholesterolaemia
- Combined oral contraceptive pill
- Vasculitis
- Infective endocarditis
How does a stroke in the anterior cerebral artery present?
- Leg weakness (> arm weakness)
- Sensory disturbances in leg
- Gait apraxia (loss of ability to have normal function of the lower limbs such as walking)
- Truncal ataxia - patients can’t sit or stand unsupported and tend to fall backwards
- Incontinence
- Drowsiness - since part of consciousness is in the frontal lobe
- Akinetic mutism - Decrease in spontaneous speech
How does a stroke in the middle cerebral artery present?
- Contralateral arm and leg weakness
- Contralateral sensory loss
- Hemianopia
- Aphasia (inability to understand or produce speech)
- Dysphasia (deficiency in speech generation)
- Facial droop
How does a stroke in the posterior cerebral artery present?
- Contralateral homonymous hemianopia (loss of half the vision on the same side in both eyes)
- Cortical blindness (eye healthy, but brain issue causing blindness)
- Visual agnosia (cannot interpret visual information but can see)
- Prosopagnosia - cannot see faces
- Colour naming and discriminate problems
- Unilateral headache - RARE in ischaemic stroke, so if you see headache then think PCA
What is a lacunar stroke?
Small subcortical strokes e.g affecting the midbrain, internal capsule etc.
What are the symptoms of a lacunar stroke?
- Unilateral weakness (and / or sensory deficit) of face and arm, arm and leg or all three
-Pure sensory loss - Ataxic hemiparesis
- Cerebellar and motor symptoms
(In general only 1 modality tends to be affected and patients can be defined as having lacunar stroke with one symptom)
What tests would you do if a stroke is suspected?
- Urgent CT/MRI of the head
- Pulse, BP, ECG
- Bloods
What is the underlying treatment in an ischaemic stroke?
Maximise reversible ischaemic tissue:
- Ensure hydration
- Keep O2 sat >95%
- If ischaemic stroke confirmed by CT then proceed to thrombolysis
What must be done first before performing thrombolysis?
MRI/CT of the head to exclude hemorrhage
When would thrombolysis be contraindicated?
- Recent surgery last 3 months
- Recent arterial puncture
- History of active malignancy (high vascular thus increased bleeding risk)
- Evidence of brain aneurysm
- Patient on anticoagulation
- Severe liver disease (abnormal clotting)
- Acute pancreatitis
- Clotting disorder
What are some risk management strategies in patients would are susceptible to stroke?
- Platelet treatment (lifelong if already had stroke) eg aspirin + dipyridamole or clopidogrel
- Cholesterol treatment like statins (eg simvastatin)
- AF treatment (eg warfarin or new oral anticoagulants eg pixiban)
- Blood pressure treatment eg ACEIs eg ramipril
