Stroke 2 - Ischaemic Stroke Flashcards
Ischaemic Stroke Summary?
- 85% strokes of the the ischaemic type
- Intravenous tissue plasminigen activator (tPA) given within 4.5 hours of stroke onset
- Endovascular interventions given: clot retrieval or intra arterial thrombolysis
Key factors?
vision loss or visual field deficit
weakness
aphasia
impaired co-ordination (ataxia)
Other diagnostic factors?
- hx TIA
- sudden onset of
symptoms - negative symptoms (i.e., loss of function)
- altered sensation
- vertigo/dizziness
- nausea and/or vomiting
- headache
- neck or facial pain
- diplopia
- sensory loss
- dysarthria
- gaze paresis
- miosis, ptosis, and facial anhidrosis (hemilateral)
- altered level of consciousness/coma
- confusion
- arrhythmias, murmurs, or pulmonary oedema
1st Diagnostic investigations?
CT head MRI brain serum glucose serum electrolytes serum urea and creatinine cardiac enzymes ECG FBC prothrombin time (PT) and PTT (with international normalised ratio)
Investigations to consider?
serum toxicology screen stool guaiac test CXR CT angiography MR angiography CT or MR venography carotid ultrasound transcranial Doppler ultrasound conventional (invasive) angiography
Transient ischaemic attack (TIA) is defined as ?
A transient (i.e., <24 hours) episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia without acute infarction.
A classification scheme for ischaemic stroke ?
Trial of Org 10172 in Acute Stroke Treatment (TOAST) provides a framework for determining the stroke mechanism, with implications for identifying the underlying aetiology:
Large artery atherosclerosis?
Affects the extracranial carotid or vertebral arteries, or less commonly the major intracranial arteries. It is a site for thrombus formation that then embolises to distal sites and/or occludes the vessel.
Small vessel (lacunar) stroke?
Caused by thrombotic occlusion of a small penetrating artery affected by lipohyalinosis (lipid accumulation due to ageing and HTN), resulting in a <1.5-cm infarct in the perfusion territory of the affected small vessel.
Cardioembolism?
Thrombus formation in the heart, which then embolises to the intracranial circulation, and is associated with cardiac disease such as atrial fibrillation. Accumulating evidence suggests that aortic atherosclerotic plaque is another potential source of thrombus formation with embolism.
Ischaemic stroke can be broadly classified as?
- Primary vascular pathologies
- Cardio-aortic pathologies
- Haematological pathologies
Primary vascular pathologies?
(e.g., atherosclerosis, arterial dissection, migraine, or vasculitis) that directly reduce cerebral perfusion and/or result in artery-to-artery embolism (i.e., stenosis or occlusion of a distal artery by an embolus originating in a proximal artery)
Cardio-aortic pathologies?
(e.g., atrial fibrillation, myocardial ischaemia/infarction, patent foramen ovale, aortic arch atherosclerosis) that lead to cerebral arterial occlusion due to embolism
Haematological pathologies?
(e.g., prothrombotic hypercoagulable or hyperaggregable states) that directly precipitate cerebrovascular thrombosis (particularly venous), or facilitate systemic venous or intracardiac thrombus formation and cardioembolism.
Trial of Org 10172 in Acute Stroke Treatment (TOAST criteria)?
Classifies ischaemic stroke according to pathophysiology:
Large artery atherosclerosis
Infarction in the perfusion territory of an extracranial or intracranial artery with >50% stenosis, and no other likely cause of stroke.
Cardioembolism
Infarction in the presence of at least 1 cardiac condition strongly associated with stroke, such as atrial fibrillation.
Small vessel occlusion
Infarction <1.5 cm in diameter in the perfusion territory of a small penetrating blood vessel.
Stroke of other determined aetiology
Examples include cerebral infarction caused by vasculitis, arterial dissection, and hypercoagulable states.
Stroke of indeterminate aetiology
Infarction in the setting of 2 or more different potential aetiologies, no potential aetiology despite complete diagnostic evaluation, or an incomplete evaluation.
