Stroke Flashcards
Define stroke
The damage or killing of brain cells starved of oxygen as a result of the blood supply to part of the brain being cut off.
Infarction or bleeding into the brain manifests with sudden onset focal CNS signs
What is a TIA?
Transient ischaemic attack - a stroke that recovers within 24 hours from the onset of symptoms
What is a stroke syndrome?
Constellation of signs and symptoms produced due to occlusion or damage of an artery supplying part of the brain
What percentage of strokes are ischaemic?
85%
What percentage of strokes are haemorrhagic?
10%
What are the 5 subtypes of ischaemic stroke? (Toast classification)
Large artery atherosclerosis (thrombus or embolus) Small artery strokes (lacunae) Cardioemoblic Other determined pathology Undetermined
What are some stroke risk factors?
HTN Diabetes Hyperlipidaemia Heart disease - AF, valvular heart disease, PVD Smoking Alcohol Cocaine Age esp over 55 Haematological disorders - multiple myeloma, sickle cell disease, polycythemia Vera COCP Increased homocysteine
What does the anterior cerebral artery supply?
The medial frontal and parietal area of brain
Anterior corpus collosum
How would a stroke involving the anterior cerebral artery present?
Contralateral hemiparesis of lower limb - initially flaccid paralysis then spasticity -> UMN signs
Incontinence (damage to paracentral lobule x suppresses micturition)
Contralateral loss of all sensory modalities in lower limb
Inability to understand and/ or produce speech (left hemisphere)
What does the middle cerebral artery supply?
Lateral frontal, parietal and superior temporal part of brain
Deeper branches- basal ganglia, internal capsule, macular cortex
How would a stroke involving the middle cerebral artery present?
Contralateral paresis - upper limb and face. If proximal occlusion: internal capsule also affected (carries descending motor fibres) so leg may also be affected
Contralateral loss of all sensory modalities upper limb and face
Vision: proximal - contralateral homonymous hemianopia, distal - contralateral homonymous superior or inferior quadrantinopia
Speech: depends on dominant hemisphere and which branch of MCA occluded. If dominant hemisphere (most likely left) affected: global aphasia - main trunk occlusion. OR Broca’s expressive aphasia or Wernicke’s receptive aphasia
If non dominant (likely right) side affected:
- hemispatial neglect
- tactile extinction
- visual extinction
- anosognosia
Main trunk occlusion of MCA can cause considerable cerebral oedema and raised intracranial pressure. What term is used to describe this?
Malignant MCA
Decompressive hemicraniotomy needed
What does the posterior cerebral artery supply?
Inferior temporal and occipital region
How would a stroke involving the posterior cerebral artery present?
Contralateral homonymous hemianopia with macular sparing
What do the cerebellar arteries supply?
Cerebellum and brainstem
What signs can be seen as a result of a cerebellar stroke?
Dysdiadochokinesia Ataxia Nystagmus Intention tremor Slurred speech (staccato) Hypotonia (more subtle than LMN lesion)
Due to the cerebellar arteries also supplying the brainstem, what signs can be see as a result of a proximal occlusion?
Cerebellar signs
Brainstem signs - crossed deficits
-> damage to ascending/ descending tracts affects contralateral side, damage to CNS or their nuclei gives ipsilateral signs
What do the lenticulostriate arteries supply?
Internal capsule (posterior limb carries descending motor fibres)
A stroke involving the lenticulostriate arteries would cause…
Contralateral motor hemiparesis
What does the thalamoperforator artery supply?
Part of the thalamus
What are some stroke mimics?
Hypoglycaemia
Epilepsy - post ictal
Migraine (hemiplegic)
Intracranial tumours/ infections
Are the signs of a stroke sudden in onset or do they occur over a long time?
Sudden in onset
What are some haemorrhagic pointers?
Meningism Severe headache Decrease in level of consciousness Nausea and vomiting Seizure
What are some ischaemic pointers?
Carotid bruit
AF
Past TIA
IHD
What imaging needs to be done to rule out haemorrhagic stroke?
CT scan
Once haemorrhagic stroke is excluded, what medication should be given?
Aspirin 300mg (continue for 2 weeks then switch to long term antithrombotic treatment)
When should thrombolysis be considered?
Haemorrhagic stroke excluded
Onset of symptoms less than 4.5 hours ago (best results within 90 minutes)
What is the thrombolysis agent of choice?
Alteplase
Or recombinant tissue plasminogen activator (rt-PA)
What should be done 24 hours post lysis?
A CT to identify bleeds (non contrast)
What are the contraindications to thrombolysis?
Major infarct or haemorrhage on CT Mild/ non disabling deficit Recent surgery or trauma Previous CNS bleed AVM/ aneurysm Severe liver disease, varices, portal hypertension Low platelets Anticoagulants or INR>1.7