Chapter 39. Stroke

(Circulation 2010;121:e4; Lancet 2008:371:1612)

• 3rd most common cause of death after IHD, 9% of global deaths; 25% of ischemic stroke patients die within a month & 50% by 1y
• Ischemic stroke
  • Progressive accumulation of lipids & inflammatory cells in affected arteries & hypertrophy of arterial smooth muscle create formation of plaque
    • Sheer stress can rupture the plaque creating a clot
    • The clot can cause an occlusion to become an embolism
  • Stasis of blood in the heart can cause a direct embolism to the cerebral circulation
  • Result of clot formation or embolism is arterial circulation blockage leading to ischemia
• Hemorrhagic stroke: blood causes irritation to brain & mass effect; the larger the blood volume, the more severe the stroke

Classification

• Transient ischemic attack (TIA) (Stroke 2011;42:227) (predictor for ischemic stroke)
  • Transient episode of neurological dysfunction caused by ischemia, not infarction, lasting <24h
  • 90-d risk of stroke after TIA up to 17%, greatest risk in 1st wk
• Ischemic stroke (87%); hemorrhagic stroke (13%)
• DDx: migraine, head trauma, brain abscess, encephalitis, brain tumor, seizure with postictal paralysis, hypoglycemia

(Pharmacotherapy 2010;30:493)

• 5 cardinal stroke signs: HA, dizziness, vision impairment, speech impairment, weakness
• CT scan w/o contrast to r/o hemorrhage & determine size, location, vascular distribution of infarct
• Neurological deficits determined with National Institutes of Health Stroke Scale (NIHSS) & modified Rankin Scale (mRS)

Ischemic Stroke

Treatment Goals: ↓ neurological injury, ↓ M&M, prevent complications & recurrence

Pharmacological Treatment

Acute Inpatient Management

• Alteplase (rt-PA)
  • IV tissue plasminogen activator (fibrinolytic) with Class I, level A evidence in stroke
  • Efficacy: 30% more likely than placebo to have minimal or no disability at 90d if administered within 3h of symptoms (N Engl J Med 1995;333:1581)
  • Safety: symptomatic intracranial hemorrhage within 36h 6.4% rt-PA vs 0.6% placebo (p <0.001); no difference in mortality (NINDS trial N Engl J Med 1995;333:1581)
  • Safe + effective with expansion of administration to 4.5h of symptoms; now AHA/ASA recommendation (N Engl J Med 2008;359:1317)
  • No antithrombotics or anticoagulants for 24h after administration (Pharma­cotherapy 2010;30:493)
  • Closely monitor pts for blood pressure & neurological changes
• UFH & LMWH
  • AHA/ASA recommend against treatment doses (Class III, level A)
  • ACCP Chest guidelines recommend for cardioembolic ischemic stroke
  • No LMWH treatment → risk of bleeding > ↓ in death or disability (Stroke 2000;31:1770)
• ASA 325mg/d within 24 to 48h (AHA/ASA Class I, level A)
  • Do not start until 24h after alteplase
    • However, if pt took PO ASA shortly before hospital admission, not absolute CI to alteplase therapy