Stroke, Ischemic

Source: Fagan SC, Hess DC. Chapter 27. Stroke. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7973981. Accessed June 27, 2012.

• Apoplexy
• Cerebrovascular accident (CVA)

• Interruption of blood flow to area of brain, causing death of brain cells in area.

• Local thrombus formation (e.g., cerebral atherosclerosis)
• Emboli from intra- or extracranial arteries that occlude cerebral artery
• Unknown causes

• Carotid atherosclerosis: Ruptured plaques lead to thrombus formation that may cause local occlusion or dislodge and travel distally, eventually occluding cerebral vessel.
• Cardiogenic embolism: Stasis of blood flow in atria or ventricles leads to formation of clots that dislodge and travel through aorta to cerebral circulation.
• Resulting arterial occlusion decreases cerebral blood flow and causes ischemia and infarction distal to occlusion.

• Stroke (including ischemic and hemorrhagic types) leading cause of adult disability in United States.
• African Americans have stroke rates twice those of whites.
• Some states in southeastern United States have stroke mortality rates more than twice national average.

• Preventive measures directed toward reducing or eliminating modifiable risk factors for stroke.

• Nonmodifiable risk factors:
  • Increased age
  • Male sex
  • Race (African Americans, Asian–Pacific Islanders, Hispanics)
  • Family history of stroke
  • Low birth weight
• Major modifiable risk factors:
  • Hypertension
  • Cardiac disease (especially atrial fibrillation)
• Other risk factors:
  • Diabetes mellitus
  • Dyslipidemia
  • Cigarette smoking

• May need to obtain medical history from family members or others because cognitive or language deficits may preclude patient from giving reliable history.

Signs and Symptoms

• Symptoms:
  • Weakness on one side of body
  • Inability to speak
  • Loss of vision
  • Vertigo
  • Falling
  • Headache
• Signs of neurologic dysfunction depend on brain area involved.
  • Hemi- or monoparesis and hemisensory deficits common.
  • Posterior circulation involvement may present with vertigo and diplopia.
  • Anterior circulation strokes result in aphasia.
  • Other potential signs:
    • Dysarthria
    • Visual field defects
    • Altered levels of consciousness may be present.

Laboratory Tests

• Obtain tests for hypercoagulable states (protein C, protein S, antithrombin III) only when cause cannot be determined based on review of risk factors.
• Obtain antiphospholipid antibodies in patients younger than age 50 and those who have had multiple thrombotic events or livedo reticularis.

Imaging

• Computed tomography (CT) head scan
• Magnetic resonance imaging (MRI) of head reveals ischemic areas with higher resolution and earlier than CT scan.
• Carotid Doppler (CD) studies can identify degree of stenosis in carotid arteries.
• Transthoracic echocardiogram (TTE) can detect valve or wall motion abnormalities that are sources of emboli.
• Transesophageal echocardiogram (TEE) more sensitive for left atrial thrombus.
• Transcranial Doppler (TCD) can determine presence of intracranial sclerosis (e.g., middle cerebral artery stenosis).

Diagnostic Procedures

• Electrocardiogram (ECG) will determine whether atrial fibrillation is possible cause.

Differential Diagnosis

• Hypoglycemia
• Transient ischemic attack
• Intracerebral hemorrhage or other mass lesion (e.g., tumor)
• Focal seizure
• Migraine
• Peripheral causes of vertigo (Meniere’s disease)
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