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Approach to a patient with stroke - Pathophysiology of stroke
1. Approach to a patient with stroke AshwinHaridas Asem Ali Ashraf Adam EAH Adam
2. Definitions Stroke Clinical syndrome of rapid onset of focal deficits of brain function lasting more than 24 hours or leading to death Transient Ischemic attack (TIA) Clinical syndrome of rapid onset of focal deficits of brain function which resolves within 24 hours
3. Definitions Progressive Stroke A stroke in which the focal neurological deficits worsen with time Also called stroke in evolution Completed Stroke A stroke in which the focal neurological deficits persist and do not worsen with time
4. Epidemiology Third most common cause of death after cancer and ischeamic heart disease Most common cause of severe physical disability Prevalence of stroke in India is about 1.54 per 1000 Death rate is about 0.6 per 1000 Incidence and prevalence of stroke is on the rise due to increasing adoption of unhealthy lifestyle & an increasing life expectancy
13. Thrombotic Stroke Atherosclerosis is the most common pathology leading to thrombotic occlusion of blood vessels Hypercoagulable disorders – uncommon cause Antiphospholipid syndrome Sickle cell anemia Polycythemiavera Homocysteinemia Vasculitis: PAN, Wegener’s granulomatosis, giant cell arteritis
14. Thrombotic Stroke Lacunar stroke Accounts for 20% of all strokes Results from occlusion of small deep penetrating arteries of the brain Pathology: lipohyalinosis & microatheroma Thrombosis leads to small infarcts known as lacunes Clinically manifested as lacunar syndromes
15. Embolic Stroke Cardioembolic stroke Embolus from the heart gets lodged in intracranial vessels MCA most commonly affected Atrial fibrillation is the most common cause Others: MI, prosthetic valves, rheumatic heart disease Artery to artery embolism Thrombus formed on atherosclerotic plaques gets embolized to intracranial vessels Carotid bifurcation atherosclerosis is the most comon source Others: aortic arch, vertebral arteries etc.
17. Blood supply to the brain is autoregulated Blood flow If zero leads to death of brain tissue within 4-10min <16-18ml/100g tissue/min infarction within an hour Ischemia leads to development of an ischemic core and an ischemic penumbra Pathophysiology of Ischemic Stroke
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19. Ischemic Penumbra Tissue surrounding the core region of infarction which is ischemic but reversibly dysfunctional Maintained by collaterals Can be salvaged if reperfused in time Primary goal of revascuralization therapies
20. Thrombus/embolus Hypoperfusion ATP depletion Failure of Na+/K+ATPase membrane ionic pump Activation of pro-coagulant pathways Membrane depolarization & cytotoxic cellular edema Free fatty acid release Calcium entry Glutamate release Activation of lipid peroxidases, proteases & NO synthase Destruction of intracellular organelles, cell membrane & release of free radicals Liquefactive necrosis
21. Hemorrhagic Stroke Two types Intracerebral hemorrhage(ICH) Subarachnoid hemorrhage(SAH) Higher mortality rates when compared to ischemic stroke
26. Pathophysiology Of Hemorhagic Stroke Explosive entry of blood into the brain parenchyma structurally disrupts neurons White matter fibre tracts are split Immediate cessation of neuronal function Expanding hemorrhage can act as a mass lesion and cause further progression of neurological deficits Large hemorrhages can cause transtentorial coning and rapid death