Strokes Flashcards
Where do the majority of stroke occur?
Territories supplied by middle cerebral artery
What occurs when there is an infarct in the vertebral arteries?
Infarct in posterior inferior cerebellar artery (PICA - largest branch)
Lateral medullary syndrome (Wallenberg syndrome)
S&S:
- ipsilateral facial deficit in pain and temperature sensation (spinal trigeminal nucleus lost)
- ipsilateral cerebellar ataxia and incoordination (inferior cerebellar peduncle)
- dysarthria/dysphagia/reduced gag reflex (nucleus ambiguous)
- contralateral deficit in pain and temperature in trunk and limbs (spinothalamic tract)
- vertigo (vestibular nucleus)
- ipsilateral Horner’s syndrome
What areas of the brain are supplied by the anterior cerebral artery?
Superior and medial parts of frontal lobe
- prefrontal cortex
- pre-central gyrus
- post-central gyrus
- Broca’s area
Corpus callosum
note: no collateral circulation
What areas of the brain are supplied by the middle cerebral artery?
Majority of the lateral surface of cerebral hemisphere (apart from the superior parietal lobe and inferior temporal lobe and occipital lobe)
- Broca’s area
- Wernicke’s area
- pre-central gyrus
- post-central gyrus
+ internal capsule and basal ganglia
What areas of the brain are supplied by the posterior cerebral artery?
Midbrain
Thalamus
Inferior parts of temporal and occipital lobes
What areas of the brain are supplied by the basilar artery?
Most of the brainstem
What are the symptoms associated with an infarct in the posterior cerebral artery?
Loss of colour vision
Visual agnosia
Visual field disturbances
What is the definition of a stroke?
Clinical syndrome of abrupt loss of focal brain function lasting over 24hrs or causing death that is either due to spontaneous haemorrhage into brain substance or inadequate blood supply to a part of the brain
note: includes subarachnoid haemorrhage
What is the definition of a transient ischaemic attack?
Sudden onset of focal disturbance of brain function (occasionally global) presumed to be of vascular origin which resolves completely within 24hrs
note: the more time it takes to resolve, the more likely it is to be a stroke
note: 24hrs is a controversial definition
Contrast the incidence of the different types of stroke.
80%-85% are cerebral infarcts
10%-15% are intracerebral haemorrhages
5% are subarachnoid haemorrhages
What are the different types of intracerebral haemorrhages?
Primary = spontaneous; no structural lesion
Secondary = underlying lesion e.g. tumour, arteriovenous malformation
Haemorrhagic transformation of infarct (extensive infarct —> cerebral oedema —> fragile blood vessels —> haemorrhage)
What is the aetiology of cerebral infarcts?
- large vessel atheroma/embolism
- cardiac embolism
- small vessel disease/lacunae
- non-atheromatous arterial disease (arteritis)
- blood disorders
- cryptogenic (10%)
What is the aetiology of intracerebral haemorrhages?
- hypertension microaneurysms/lipophyalinosis (vessel wall thickening and reduced lumen diameter) (40%)
- aneurysms or arteriovenous malformations (15%)
- amyloid angiopathy (amyloid deposits in CNS blood vessels) (10%)
- haemostatic anticoagulant, thrombolytic thrombocytopenia (10%)
- cocaine or amphetamines
- tumour
- venous thrombosis (esp. in diabetes)
- peri-partum pregnant women
What are the classes within the Oxford Classification of Strokes?
Total anterior circulation stroke (TACS)
Partial anterior circulation stroke (PACS)
Lacunar stroke (LACS)
Posterior circulation stroke (POCS)
note: all are strokes due to cerebral infarcts
Outline the incidence, pathophysiology, symptoms, and outcome of total anterior circulation strokes.
20% of strokes
Occlusion of internal carotid artery or proximal occlusion of middle cerebral artery
Large volume infarct (superficial and deep territories)
S&S (all 3 req.):
- contralateral hemiparesis +/- hemianaesthesia
- contralateral hemianopia
- higher cerebral dysfunction e.g. dysphasia, dyspraxia
50% die within 1yr
Outline the incidence, pathophysiology, symptoms, and outcome of partial anterior circulation strokes.
35% of strokes
Occlusion of a branch of middle cerebral artery
Restricted area of infarct
S&S:
- 2 of the 3 symptoms seen in TACS (contralateral hemiparesis, contralateral hemianopia, higher cerebral dysfunction) OR
- restricted motor deficit in face OR arm OR leg only OR
- isolated cortical signs
High early recurrence rate
Outline the incidence, pathophysiology, symptoms, and outcome of lacunar strokes.
20% of strokes
Single perforating artery occluded
Affects the basal ganglia or pons
S&S:
- pure motor OR
- pure sensory OR
- sensorimotor
- ataxic hemiparesis
Silent (therefore underdiagnosed)
Outline the incidence, pathophysiology, symptoms, and outcome in posterior circulation strokes.
25% of strokes
Affects brainstem, cerebellum, or occipital lobe
Complex presentation
Differentiate the symptoms which result from strokes affected the dominant and non-dominant hemispheres.
85% of people have left hemisphere as dominant (even in left-handed people)
Dominant cortex affected =
- dysphagia
- dysgraphia
- dyslexia
Non-dominant cortex affected =
- visual spatial disorder (visual association area affected)
- neglect (visual association area affected)
What are some important considerations when taking a stroke history, and why?
Stroke or non-stroke? (different management)
TIA or stroke? (different investigations)
Type of stroke? (location/pathology cause different onset time and neurological symptoms)
Cause of stroke?
Suitable for thrombolysis (time is brain)
What are some important red flag symptoms in a stroke history?
Bleeding
- headache
- seizure
Raised intracranial pressure
- headache
- vomiting
- drowsiness
Aetiology e.g. cardiac symptoms
note: atypical presentations (esp. in elderly) include delirium, confusion, collapse, and incontinence
What might be seen on a CT head in a stroke?
Infarcts are grey
Blood is white
Oedema is dark grey and causes midline shift
note: if bleeding is in basal ganglia, it is too deep for neurosurgery
Give some examples for differential diagnoses for stroke.
- hypoglycaemia = difficulty speaking, floppy one side (symptoms improve when [glucose] increases)
- migrainous aura
- epilepsy
- space occupying lesion
- demyelinating disorders e.g. MS
- labyrinthine disorders
- retinal bleed/infarct
- peripheral neuropathy
- myopathies
- delirium
- hyperventilation (transient)
- functional v.s. psychological
What are some important signs seen on examination in stroke?
Baseline obs:
- BP
- pulse rate and rhythm
- proteinuria/haematuria
?genetic/hereditary:
- telangiectasia
- hyperlipidaemia
- endocarditis/stigmata of vasculitis
- neoplastic screen
CVS:
- ?cardiac source of embolism (arrhythmias, valvular defects)
- ?vascular source of embolism (carotid/renal bruits, peripheral pulses)
Resp:
- dysphagia may lead to aspiration pneumonia
What are some important investigations for stroke?
- blood glucose (rule out hypoglycaemia)
- FBC
- INR
- U&Es, LFTs, TFT, lipids (baseline for prescribed drugs e.g. statins)
- ECG (look for AF which increases risk of mortality)
- CXR (where indicated)
- urgent CT head when thrombolysis is an option (look for bleeding which would contra-indicate thrombolysis)
note: early normal CT does not rule out ischaemic stroke or infarct (just rules out bleeding)
+ MRI brain in certain situations
+ carotid ultrasound (?carotid embolism)
+ echocardiogram (if cause is unknown e.g. patent foramen ovale)
+ 24hr cardiac monitoring (if cause is unknown e.g. arrhythmias)
What are some important additional investigations in cryptogenic strokes or in young patients with stroke?
- full coagulation profile (e.g. if unable to conceive)
- thrombophilia screen (e.g. family history of DVT)
- antiphospholipid antibodies
- autoimmune screen
- fasting plasma homocysteine
- blood cultures
- thyroid function
- syphilis serology
- HIV serology
What is the management for an acute stroke?
IV thrombolysis (alteplase) IF:
- CT has excluded bleeding and established infarct
- no bleeding risk e.g. not on warfarin
- any patient within 3hrs, consider anybody
What is the outcome of IV thrombolysis in acute stroke?
1/3 will improve (of those 1/10 will fully recover)
3% will be worse overall
1/14 will have intracerebral haemorrhage —> 1/20 of those will become worse
Give some examples of how to prevent future strokes in stroke patients.
Anti-thrombotics
Treat hypertension, hypercholesterolaemia, diabetes
Carotid surgery in carotid stenosis
What are the different segments of the internal carotid artery?
Bouthillier classification
- cervical
- petrous
- lacerum
- cavernous
- opthalmic
- posterior communicating (lesion causes 3rd nerve palsy)
- anterior choroidal (supplies posterior limb of internal capsule and optic chiasm; lesion causes visual field disturbances)
