Ischaemic stroke Flashcards
what is the definition of ischaemic stroke?
Caused by vascular occlusion or stenosis
a clinical syndrome consisting of rapidly developing clinical signs of focal (or global) disturbance of cerebral function, lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin
what is the epidemiology of ischaemic stroke?
Leading cause of morbidity and mortality
More common over 55
Lower levels of education
african-american or hispanic
what is the aetiology of ischaemic stroke?
Blood vessels in the brain are blocked. Two types, Thrombotic ischaemic stroke or Embolic ischaemic stroke. Usually atherosclerotic plaque or a clot in a larger artery ruptures, travels downstream, gets trapped in a narrower artery in the brain. Embolic strokes are common complications of atrial fibrillation and atherosclerosis of the carotid arteries. 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 is caused by thrombotic occlusion of a small penetrating artery affected by lipohyalinosis (lipid accumulation due to ageing and hypertension), resulting in a <1.5-cm infarct in the perfusion territory of the affected small vessel. Cardioembolism results from 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. Strokes of other determined aetiology may be caused by various diseases of the intracranial or extracranial vessels (e.g., dissection, vasculitis, venous thrombosis) or haematological system (e.g., sickle cell anaemia, antiphospholipid antibody syndrome, and other hypercoagulable states). Strokes of indeterminate aetiology, despite complete work-up, are not uncommon. In the Northern Manhattan Stroke Study, 32% of strokes had no identifiable aetiology.
what are the risk factors for ischaemic stroke?
Older age Family history of stroke History of ischaemic stroke or TIA Hypertension Smoking DM Atrial fibrillation Comorbid cardiac conditions Carotid artery stenosis Sickle cell disease Dyslipidaemia Lower level of education
what is the pathophysiology of ischaemic stroke?
Primary vascular pathologies (e.g., atherosclerosis, aortic arch 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) Cardiac pathologies (e.g., atrial fibrillation, myocardial ischaemia/infarction, patent foramen ovale) 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.
what are the key presentations of ischaemic stroke?
Suspect stroke in anyone presenting with an acute onset, ongoing focal neurological deficit that cannot be explained by hypoglycaemia or other stroke mimics.
Usually unilateral:
Facial weakness (MCA)
Unilateral weakness of the upper and/or lower limb (MCA/ACA)
Unilateral sensory loss of upper and/or lower limb (MCA/ACA)
Speech problems (MCA, dominant hemisphere)
Visual defects (PCA)
Disorders of perception (PCA)
Disorders of balance (posterior circulation)
Coordination disorders (posterior circulation)
what are the signs of ischaemic stroke?
Suspect stroke in anyone presenting with an acute onset, ongoing focal neurological deficit that cannot be explained by hypoglycaemia or other stroke mimics
what are the symptoms of ischaemic stroke?
Usually unilateral:
Facial weakness (MCA)
Unilateral weakness of the upper and/or lower limb (MCA/ACA)
Unilateral sensory loss of upper and/or lower limb (MCA/ACA)
Speech problems (MCA, dominant hemisphere)
Visual defects (PCA)
Disorders of perception (PCA)
Disorders of balance (posterior circulation)
Coordination disorders (posterior circulation)
what are the first line and gold standard investigations for ischaemic stroke?
Imaging to detect bleeding or blockage, detect tissue damage
CT - hypoattenuation (darkness) of the brain parenchyma, loss of grey matter-white matter differentiation, and sulcal effacement, hyperattenuation (brightness) in an artery indicates clot within the vessel lumen (if picked up, usually irreversible, pick up late)
Serum glucose - may be abnormal
Serum electrolytes - may be abnormal
Serum urea and creatinine - may show renal failure
Cardiac enzymes - may show cardiac ischaemia
FBC - may show anaemia or thrombocytopenia
ECG - arrhythmia or ischaemia
CTA (CTantigiograophy) - arterial occlusion or stenosis (can pick up earlier)
CT perfusion - shows areas with reduced blood flow that may be at risk for subsequent infarction
what are the differential diagnoses for ischaemic stroke?
Hemorrhagic stroke
TIA
Hypoglycaemia
Labyrinthine disorders (labyrinthitis, vestibular neuronitis, BPPV, Meniere’s disease)
Migraine (hemiplegic migraine, unilateral hemiparesis).
Mass lesions (subdural haematoma, cerebral abscess, tumours)
Postictal weakness (also known as Todd’s paralysis) , focal seizures, and generalised seizures
Functional hemiparesis
how is ischaemic stroke managed?
Arrange emergency admission to a specialist stroke unit, 999 (if by telephone of clinically appropriate) or 1 hour admission
Thrombolysis not indicated:
Alteplase, mechanical thrombectomy, antiplatelet agent, venous thromboembolism prophylaxis and early mobilisation, high intensity statin
Thrombolysis or more the 4.5 hours:
Mechanical thrombectomy, antiplatelet agent, venous thromboembolism prophylaxis and early mobilisation, high intensity statin
how is ischaemic strokes monitored?
Monitor: Level of consciousness Blood glucose Blood pressure Oxygen saturations Hydration Temperature Cardiac rhythm and rate. Monitor the patient for complications such as signs of raised intracranial pressure and seizures.
what are the complications of ischaemic stroke?
DVT, hemorrhagic transformation of ischaemic stroke, alteplase related orolingual oedema, depression, fatigue, pneumonia
what is the prognosis of an ischaemic stroke?
Patients treated with alteplase (if given within 4.5 hours of onset of symptoms) have a better functional outcome than patients not treated with alteplase
