Stroke

  • Transient ischemic attack (TIA):  brief, reversible episodes of nonconvulsive disturbances
    • duration is < 24 hours
    • Causes a temporary focal neurological deficit
  • Stroke:  cerebral infarction/cerebrovascular event causing symptoms to last 24 hours or longer
  • Significance of the stroke will depend on location & length of time in which blood flow is disrupted
  • Cardiovascular disease is the most common cause of stroke (thrombotic stroke–starts outside the brain)
  • Embolic stroke (cardiogenic embolism):  occurs when an embolism originates elsewhere in the body & eventually becomes lodged in a small arterial vessel  (embolic process isn’t local)
    • May have an arterial source (plaque of the aortic arch) or a cardiac source (MI, a-fib, etc)
  • Patients who experience a hemorrhagic stroke have a poorer prognosis than patients who’ve experienced an ischemic stroke
    • Intracerebral hemorrhage resulting in a localized hematoma caused by HTN, trauma, illicit drug use, vascular abnormalities
    • Subarachnoid hemorrhage:   blood gets into CSF causing rapidly increased intracranial pressure
      • Symptoms:  sudden & severe headache (“worst of my life”)
  • Risk factors for ischemic stroke (KNOW THESE):
    • Risk of stroke doubles for each decade after 55
    • Men, family history & every race besides caucasian
    • HTN (most important risk factor), diabetes, a-fib most important & treatable cardiac cause of stroke), sickle cell disease
      • Desired BP < 130/80      (ACE-I & thiazides have the most benefit)
      • LDL goal < 100 mg/dL   (use statins)                      < 70 for CAD
    • Smoking, asymptomatic carotid stenosis, dyslipidemia, coronary HD, lifestyle factors, oral contraceptives, prego, Peripheral artery disease
  • S/S of ischemic stroke:  FACE (face, arm, speech, time)
  • Don’t treat BP unless it’s > 220/120
    • If it is above this number then give them either IV labetalol, nitroprusside or nicardipine
  • CTs are used to diagnose hemorrhagic strokes  (not used for ischemic strokes)
  • MRIs are more sensitive than CTs but aren’t as readily available
  • Treatment goals of acute stroke:
    •  reduce ongoing injury, decrease mortality & LT disability
    • Prevent complications secondary to immobility & neuro dysfunction (i.e.  VTE prophylaxis, ventilator associated pneumonia, etc)
    • Prevent stroke recurrence
  • Treatment of acute ischemic stroke:  thrombolytic therapy
    • r-tPA
      • Enhances the conversion of plasminogen to plasmin
      • Total dose 0.9 mg/kg (max of 90 mg)—>  give 10% as a bolus over 1 min & then infuse the remainder over 60 minutes
        • Need to give within 3 hours of symptom onset
      • Doesn’t have a mortality benefit but it dose improve morbidity & reduce disability
      • Avoid giving heparin, warfarin, ASA or any other antiplatelet therapy for 24 hours after the initiation of r-tPA
    • ASA (160-325 mg)
      • Daily use shows a mortality benefit
      • Need to start within 48 hours of symptom onset
    • Anticoagulation therapy doesn’t show any benefit
  • Prevention of ischemic stroke:
    • ASA (81-325 mg/day) has been used but isn’t as effective as plavix
    • Plavix (clopidogrel) 75 mg/day has been shown to be slightly more effective than ASA
    • Aggrenox (200 mg dipyridamole/ 25 mg ASA) by mouth twice daily has been shown to decrease the risk of stroke better than ASA alone
      • Causes severe HA
  • Cardioembolic stroke
    • Primary prevention in a-fib patients  (calculate CHADS-2 score)
      • Use ASA if CHADS2 < 1
      • Use warfarin is CHADS2 > 2
        • Goal INR in normal patients = 2.5
        • GOAL INR in mechanical valve pts = 3
      • Dabigatran (Pradexa) is better than warfarin in patients who have non-valvular a-fib
      • If a patient has a CHADS2 = 1 & are intolerant/CI to warfarin, give ASA 81-325 or plavix 75 + ASA 81mg

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