Stroke Flashcards
What is the commonest cause of long term disability?
Stroke
What is a stroke?
Neurological loss of function of sudden onset lasting over 24 hours of vascular origin
What is a transient ischaemic attack?
Neurological loss of function lasting less than 24 hours
What are the symptoms of stroke?
Loss of power Loss of sensation Loss of speech Loss of vision Loss of coordination
What might some patients experience during a stroke?
Headache Vomiting Neck stiffness Photophobia Loss of consciousness Fit Incontinence
What is dysarthria and dysphasia?
Dysarthria - Poor articulation in speech
Dysphasia - inability to formulate language
What is nystagmus?
Involuntary eye movement
What causes a stroke?
Damage to part of the brain due to either:
- occlusion of a vessel by an emboli
- haemorrhage at ruptured vessel
Both result in ischaemia of brain tissue
What is the tissue surrounding an ischaemic event that is low in oxygen but not infarcted called?
Penumbra, still viable for several hours after event so can be saved if treated fast enough
What blood vessels make up the anterior circulation to the face and neck?
External carotid arteries
What blood vessels make up the posterior circulation to the brain?
Internal carotid arteries
What blood vessels make up the circle of willis in the brain?
Where both the external and internal carotid arteries anastomoses in the brain
How can you quickly identify the responsible artery for a stroke?
Compare symptoms to area of brain it is linked to and its associated blood vessel
What vascular system supplies the brain stem, cerebellum and occipital lobes of the brain?
The vertebra-basilar system
What vascular system supplies most of the hemispheres and the cortical deep white matter of the brain?
The carotid system
What part of the brain is linked to speech?
Broca’s area
What part of the brain is linked to movement?
Motor cortex
What part of the brain is linked to sensation?
Sensory cortex
What part of the brain is linked to swallowing, breathing, heart rate, wakefulness etc?
Brainstem
What part of the brain is linked to smell?
Frontal lobe
What part of the brain is linked to vision?
Occipital lobe
What part of the brain is linked to hearing?
Temporal lobe
What part of the brain is linked to comprehension of language?
Parietal lobe
Wernickes area
What part of the brain is linked to judgement, foresight and voluntary movement?
Frontal lobe
What part of the brain is linked to intellectual and emotional functions?
Temporal lobes
What part of the brain is linked to coordination?
Cerebellum
What is the homunculus, and what is its relevance for stroke?
Distorted scale model of a human representing the relative space human body parts occupy on the somatosensory cortex and the motor cortex
Can link symptoms to part of the brain fast
At what two points in the deep white matter cause significant damage in the event of a stroke?
Internal capsule and pons
Fibres are packed very close together here
What % of strokes are caused by infarction?
85%
What % of strokes are caused by haemorrhage?
15%
List some causes of ischaemic stroke due to infarction
Large artery atherosclerosis Cardioembolic - AF most common cause Small artery occlusion - hypertension Undetermined/cryptogenic Arterial dissection Venous sinus thrombosis
List some causes of haemorrhagic stroke
Primary intracerebral haemorrhage
Secondary haemorrhage
- subarachnoid haemorrhage
- arteriovenous malformation
What is the most common cause of cardioembolic strokes?
Atrial fibrillation
What is associated with small artery occlusion (lacunar) strokes?
Hypertension
Blockage of small arteries feeding the deep white matter (internal capsule and pons)
What can cause the rare carotid dissection?
Trauma
Idiopathic
Exertion e.g. rowing, heavy lifting
How does artery dissection cause stroke?
Tear in artery wall leads to the formation of a clot at the site of the injury, which can later embolise and block an artery and cause a stroke
What is the importance of localisation of a stroke?
Confirms diagnosis of stroke Allows better imaging selection Gives indication of cause Gives indication of prognosis Gives indication of treatment needed
What are the 4 stroke subtype?
TACS - total anterior circulation stroke
PACS - partial anterior circulation stroke
LACS - lacunar stroke
POCS - posterior circulation stroke
Describe unilateral field loss of vision
Vision in whole of one eye, due to compression of nerve supplying that eye
Compression of nerve after chiasma
Describe bitemporal hemianopia vision loss
Loss of vision in both the internal portions of each eye (cant see directly in the middle between your eyes)
Compression at chiasma
Describe homonymous hemianopia vision loss
Loss of vision on either the left or right portions of both eyes
Damage of nerve in occipital lobe
What % of strokes are total anterior circulation strokes?
20%
What are the usual symptoms of TACS?
Weakness
Sensory deficit
Homonymous hemianopia
Higher cerebral dysfunction
Usually due to occlusion of proximal MCA or ICA
What are the usual symptoms of PACS?
Restricted motor/sensory deficit e.g. one limb, hand, high cerebral dysfunction alone
Like TACS but 2/3 of TACS criteria
Due to occlusion of branches of MCA, more restricted cortical infarcts
What % of strokes are partial anterior circulation strokes?
35%
What % of strokes are lacunar strokes?
20%
What are the usual symptoms of LACS?
Pure motor commonest
Pure sensory
Sensorimotor
Ataxic hemiparesis
Due to intrinsic disease of single basal perforating arteries (end arteries)
What % of strokes are posterior circulation strokes?
25%
What are the usual symptoms of POCS?
Variable, bilateral motos/sensory deficit
- disordered eye movement
- coma
- disordered breathing
- tinnitus
- vertigo
- Horners syndrome
- ipsilateral cranial nerve palsy
- visual deficit
Which stroke subtype has the greatest mortality rate after 1 year?
TACS
Which stroke subtype has the greatest recurrence rate at 1 year?
POCS
List some risk factors for stroke
Hypertension Atrial fibrillation Cocaine use Age Sex - females protected until menopause Race - increased risk in far eastern pop Family history
Describe the investigations used for stroke
Blood tests ECG Imaging - CT - MRI - Carotid doppler - ECHO - clots in heart (AF)
What are the benefits of CT vs MRI for each type of stroke?
CT - quick - shows up blood (useful in haemorrhagic) MRI - takes 30 mins - claustrophobic and noisy - shows ischaemic stroke better than CT
What imaging is best for haemorrhagic stroke?
CT
What imaging is best for ischaemic stroke?
MRI
How can you further harm someone with a stroke?
Alteplase (fibrinolytic agent) in wrong patient
Can cause further damage or restoring blood flow to already dead tissue will have no effect
What are the SIGN guidelines for stroke treatment?
Ambulance priority (blue light) Rapid triage Immediate access to stroke specialists Rapid brain imaging Rapid specialist assessment
Describe FAST and strokes
Facial weakness
Arm weakness
Speech problems
Time to call 999
When are patients suitable for thrombolysis?
Patients with neurological deficit due to a ischaemic stroke if they are scanned within 4.5 hours of symptom onset
What are some contraindications for thrombolysis?
Age - not in patients <16yo or >80yo
Recent MI, bleeding or very high BP
What is a hemicraniectomy?
Decompression surgery following stroke with massive cerebral oedema, only offered within 48hrs of stroke onset
What treatments are offered to stroke patients?
Stroke unit(?)
Thrombolytics within 4 hrs
Aspirin for 2 days
Hemicraniectomy within 2 days if needed
What % of patients experience trouble swallowing after strokes?
50%
What is the relative % risk of an early recurrent stroke within 3 months of a previous TIA or stroke?
14%
What secondary prevention treatment is given to prevent second strokes/TIAs?
Clopidogrel or aspirin, dipyrimadole
Statin
Hypertension drugs
Anticoagulants when needed
What surgery is performed for carotid stenosis?
Carotid endarterectomy - targets anterior circulation if external carotids are >70% occluded
