Stroke Flashcards
Define stroke.
Stroke is:
- An acute onset
- Neurological deficit
- Of vascular origin
- Lasting >24hrs
It is subdivided into:
- ischaemic stroke (caused by vascular occlusion or stenosis) (87%)
- haemorrhagic stroke (caused by vascular rupture, resulting in intra-parenchymal and/or subarachnoid haemorrhage). (10% and SAH 3%)
What are the risk factors for ischaemic stroke?
Non-modifiable:
- Old age
- FH
Modifiable:
- HTN
- Smoking
- Diabetes
- Dyslipidaemia
- AF
- Comorbid cardiac conditions - valvular disease, congestive HF
- Carotid artery stenosis
- Sickle cell disease
What are the risk factors for haemorrhagic stroke?
- Cerebral amyloid angiopathy (related to dementias)
- Haemophilia
- HTN
- Smoking
- FH e.g. heritable connective tissue disease
- Anticoagulation
- Use of illicit sympathomimetic drugs
- Vascular malformations
- Moyamoya syndrome
Describe the aetiology of ischaemic stroke.
TOAST criteria classify ischaemic stroke according to pathophysiology
Large artery atherosclerosis (usually >50%) - most commonly extracranial carotid or vertebral arteries or less commonly intracranial arteries. A site for thrombus formation which embolises to distal sites.
Cardioembolism e.g. in AF a thrombus forms in heart and embolises to intracranial circulation
Small vessel occlusion (lacunar) - caused by lipid accumulation due to ageing and hypertension
Other causes: vasculitis, arterial dissection, venous thrombosis, hypercoagulable states, SCD, antiphospholipid antibody syndrome.
What is classification of stroke based on vascular territory of infarction?
Bamford classification
- Total anterior circulation infarction
- Partial anterior circulation syndrome
- Lacunar infarction
- Posterior circulation infarction.
TACI(3/3)/PACI(⅔):
- unilateral hemiparesis and/or hemisensory loss of the face, arm & leg
- homonymous hemianopia
- higher cognitive dysfunction e.g. dysphasia
POCI:
- Involves vertebrobasilar arteries
- presents with 1 of the following:
- cerebellar or brainstem syndromes
- 2. loss of consciousness
- isolated homonymous hemianopia
- e.g. Cranial nerve syndromes, Horner’s syndrome, Cerebellar syndromes
LACI (involves internal capsule, thalamus, basal ganglia)
- presents with 1 of the following:
- unilateral weakness (and/or sensory deficit) of face and arm, arm and leg or all three.
- pure sensory stroke.
- ataxic hemiparesis
What type of stroke causes cranial nerve deficits and visual field defects?
Posterior circulation stroke
Describe the cortical vascular territories of the brain.
What type of stroke affects face and/or limbs?
Anterior circulation stroke
Describe arm and leg involvement in a MCA and ACA strokes.
MCA - affects arm more than the leg
ACA - affects leg more than the arm
Due to the layout of the motor homunculus in the primary motor cortex.
What are the clinical features of an MCA stroke?
- Contralateral hemiparesis/hemiplegia
- Contralateral sensory loss
- Contralateral homonymous hemianopsia
- Left hemispheric : aphasia (Broca’s)
- Right hemispheric: visual perception deficits including left neglect
Left neglect (R lesion) is more common than right neglect because right hemisphere regulates attention more than left hemisphere so when it is knocked out there is nothing to compensate for left hemisphere in stroke.
What are the different types of aphasia?
What is the pathophysiology of haemorrhagic stroke?
Bleeding into parenchyma causes primary mechanical injury to brain tissue
Expanding haematoma may cause secondary injury due to mass effect, increased ICP and reduced perfusion causing ischaemia or even cerebral herniation
What is the most important part of a history in stroke?
Time of onset (apart from neurological symptoms)
Seconds or minutes and may be preceded by one or more TIA
What are the signs of stroke? Distinguish between ischaemic and haemorrhagic.
Worst at onset
Pointers to haemorrhagic: (unreliable)
- Meningism
- Severe headache
- Coma
Pointers to ischaemia:
- Carotid bruit
- AF
- Past TIA
- IHD
What are the signs and symptoms of cerebral infarcts?
(make up 50%)
Depending on site
- Contralateral sensory loss or hemiplegia
- Initially flaccid (floppy limb)
- Becomes spastic (UMN)
- Dysphasia
- Homonymous hemianopia
- Visuo-spatial deficit
What are the signs and symptoms of brainstem infarcts?
(make up 25%)
Varied
- quadriplegia
- disturbances in gaze and vision
- locked-in syndrome (aware but unable to respond)
What are the signs and symptoms of lacunar infarcts? What are the locations commonly affected?
(make up 25%)
Affect:
- basal ganglia
- internal capsule
- thalamus
- pons
Present with:
- ataxic hemiparesis - dysarthria/clumsy hand
- pure motor or sensorimotor
- pure sensory
Intact cognition/consciousness except in thalamic strokes
CT or MRI for stroke?
Diffusion-weighted MRI is most sensitive for acute infarct
but CT rules out primary haemorrhage
List some contraindications to thrombolysis.
What is the acute management of ischaemic stroke?
Admission to acute stroke unit
Strict supportive management -
- Glucose - 4-11mmol/L
- Oxygen - maintain at 95%
- BP - do not lower in the acute phase unless there is HTN encephalopathy; consider lowering to at least 185/110mmHg in those going for IV thrombolysis
- NBM
Exclude haemorrhage (CT) and confirm stroke then:
- Aspirin 300mg PO/PR ASAP and OD for 2 weeks or until discharge +/- PPI
- Thrombolysis - alteplase - if <4.5hrs since symptom onset. Given by stroke team only.
- +/- Thrombectomy - within 6hrs (up to 24hrs) of SO; for those with a large artery occlusion in proximal anterior circulation (on CT/MRA)
Delayed treatment
- Statin - if TC >3.5mmol/L; 48hrs after acute phase unless already had a statin prescribed
- Anticoagulation for AF - 14 days after acute phase
- Carotid endarterectomy - if non-disabling stroke in carotid territory and occlusion >70% ECST or >50% NASCET
When would you consider thrombectomy?
Otherwise given alone if:
- SO up to 24hrs ago
- Occlusion of proximal anterior circulation
- Potential to salvage brain tissue
NB: thrombectomy can be given in ADDITION to thrombolysis if within 24hrs and there is a proximal POSTERIOR infarct that has hope of tissue salvage with thrombectomy.
What is the management of haemorrhagic stroke?
Stop anticoagulants and antithrombotics
Supportive -
- Glucose - 4-11mmol/L
- BP - consider rapid BP lowering if BP 150-220mmHg and no CI (next card); lower to 140mmHg but by no more than 60mmHg within an hour.
- Oxygen- target of 95%
Neurosurgery referral
Decompressive hemicraniectomy - within 48hrs of symptoms in certain patients
What are contraindications for lowering BP in haemorrhagic stroke? (NICE)
- Tumour, AVM etc causing the stroke
- GCS <6
- Candidate for surgery to evacuate haematoma
- Massive haematoma with poor expected prognosis
Describe management for re-enablement after stroke.
MDT care on a stroke unit is essential –> better patient outcomes
- Formal assessment by SALT to assess swallowing
- Physiotherapy - minimise spasticity
- Avoid early catheterisation - ensure good bladder and bowel function
- Monitor mood - help with depression in patient and carer
- Involve carer/spouse in all aspects
