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Stroke Syndromes and Pathophysiology

Discover the different stroke syndromes, such as ischemic and hemorrhagic strokes, and delve into the pathophysiology behind strokes. Explore the impacts on brain regions and learn about various presentations and neurological deficits associated with strokes.

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Stroke Syndromes and Pathophysiology

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  1. Stroke Syndromes Dr. Meg-angela Christi Amores

  2. Stroke • Cerebrovascular disease • ischemic stroke, hemorrhagic stroke, and cerebrovascular anomalies such as intracranial aneurysms and arteriovenous malformations (AVMs) • Stroke • abrupt onset of a neurologic deficit that is attributable to a focal vascular cause • Ischemic or hemorrhagic

  3. Stroke • Ischemic Stroke • Acute occlusion of an intracranial vessel causes reduction in blood flow to the brain region it supplies • A fall in cerebral blood flow to zero causes death of brain tissue within 4–10 min • values <16–18 mL/100 g tissue per min cause infarction within an hour • values <20 mL/100 g tissue per min cause ischemia without infarction unless prolonged for several hours or days

  4. Ischemic stroke • Ischemic penumbra • Tissue surrounding the core region of infarction that is ischemic but reversibly dysfunctional • will eventually infarct if no change in flow occurs • Fever dramatically worsens ischemia, as does hyperglycemia[glucose > 11.1 mmol/L (200 mg/dL)], so it is reasonable to suppress fever and prevent hyperglycemia as much as possible

  5. Ischemic Stroke • Pathophysiology • 1) occlusion of an intracranial vessel by an embolus that arises at a distant site • (2) in situ thrombosis of an intracranial vessel, typically affecting the small penetrating arteries that arise from the major intracranial arteries • (3) hypoperfusion caused by flow-limiting stenosis of a major extracranial

  6. Stroke Syndromes • Patient presentation can localized area of the brain affected/ blood vessel occluded • Divided into: • (1) large-vessel stroke within the anterior circulation • (2) large-vessel stroke within the posterior circulation • (3) small-vessel disease of either vascular bed

  7. Stroke within the Anterior Circulation

  8. Middle Cerebral Artery

  9. Middle Cerebral Artery • If occluded at its origin: • contralateralhemiplegia • Hemianesthesia • homonymous hemianopia • gaze preference to the ipsilateral side • If dominant hemisphere: global aphasia • If non-dominant hemisphere: anosognosia, constructional apraxia, and neglect

  10. Middle Cerebral Artery • Somatic motor area for face and arm and the fibers descending from the leg area to enter the corona radiata and corresponding somatic sensory system • Paralysis of the contralateral face, arm, and leg; • sensory impairment over the same area (pinprick, cotton touch, vibration, position, two-point discrimination, stereognosis, tactile localization, barognosis, cutaneographia)

  11. Middle Cerebral Artery

  12. Middle Cerebral Artery • Motor aphasia: Motor speech area of the dominant hemisphere • Central aphasia, word deafness, anomia, jargon speech, sensory agraphia, acalculia, alexia, finger agnosia, right-left confusion (the last four comprise the Gerstmann syndrome): Central, suprasylvian speech area and parietooccipital cortex of the dominant hemisphere • Conduction aphasia: Central speech area (parietal operculum)

  13. Middle Cerebral Artery • Homonymous hemianopia (often homonymous inferior quadrantanopia): Optic radiation deep to second temporal convolution • Paralysis of conjugate gaze to the opposite side: Frontal contraversive eye field or projecting fibers

  14. Anterior Cerebral Artery

  15. Anterior Cerebral Artery

  16. Anterior Cerebral Artery • anterior limb of the internal capsule, the anterior perforate substance, amygdala, anterior hypothalamus, and the inferior part of the head of the caudate nucleus • Occlusion of the proximal ACA is usually well tolerated because of collateral flow through the anterior communicating artery and collaterals through the MCA and PCA

  17. Anterior Cerebral Artery • Paralysis of opposite foot and leg: Motor leg area • A lesser degree of paresis of opposite arm: Arm area of cortex or fibers descending to corona radiata • Cortical sensory loss over toes, foot, and leg: Sensory area for foot and leg • Urinary incontinence: Sensorimotor area in paracentral lobule

  18. Anterior Cerebral Artery

  19. Anterior Cerebral Artery • Abulia (akineticmutism), slowness, delay, intermittent interruption, lack of spontaneity, whispering, reflex distraction to sights and sounds: Uncertain localization—probably cingulategyrus and medial inferior portion of frontal, parietal, and temporal lobes • Impairment of gait and stance (gait apraxia): Frontal cortex near leg motor area • Dyspraxia of left limbs, tactile aphasia in left limbs: Corpus callosum

  20. Stroke within the Posterior Circulation • Posterior Cerebral Artery • result from atheroma formation or emboli that lodge at the top of the basilar artery

  21. Posterior Cerebral Artery • P1 Syndromes • third nerve palsy with contralateral ataxia (Claude's syndrome) or with contralateralhemiplegia (Weber's syndrome) • contralateralhemiballismus (if subthalamic n) • thalamic Déjerine-Roussy syndrome - contralateralhemisensory loss followed later by an agonizing, searing or burning pain in the affected areas

  22. Posterior Cerebral Artery • P2 Syndromes • infarction of the medial temporal and occipital lobes • Contralateral homonymous hemianopia with macula sparing • acute disturbance in memory (hippocampus) • peduncularhallucinosis - visual hallucinations of brightly colored scenes and objects • infarction in the distal PCAs produces cortical blindness • Anton's syndrome – unaware of blindness and in denial

  23. Basilar Artery • Complete basilar occlusion : • a constellation of bilateral long tract signs (sensory and motor) with signs of cranial nerve and cerebellar dysfunction • “locked-in" state of preserved consciousness with quadriplegia and cranial nerve signs suggests complete pontine and lower midbrain infarction

  24. Imaging • CT Scan • identify or exclude hemorrhage as the cause of stroke • the infarct may not be seen reliably for 24–48 h • may fail to show small ischemic strokes in the posterior fossa • MRI • reliably documents the extent and location of infarction in all areas of the brain • less sensitive than CT for detecting acute blood

  25. Imaging • Cerebral Angiography • "gold standard" for identifying and quantifying atherosclerotic stenoses of the cerebral arteries • used to deploy stents within delicate intracranial vessels • intraarterial delivery of thrombolytic agents

  26. Primary and Secondary Prevention • General Principles • medical and surgical interventions • lifestyle modifications • Evaluation of a patient's clinical risk profile • Atherosclerosis risk factors • Older age, family history of thrombotic stroke, diabetes mellitus, hypertension, tobacco smoking, abnormal blood cholesterol [particularly, low high-density lipoprotein (HDL) and/or high low-density lipoprotein (LDL)

  27. Primary and Secondary Prevention • Antiplatelet Agents • inhibiting the formation of intraarterial platelet aggregates • Aspirin, clopidogrel, and the combination of aspirin plus extended-release dipyridamole • Aspirin dose: 50–325 mg/d • Anticoagulation • For AF patients: Warfarin

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