Stroke

I. Background
Stroke is defined as an acute neurologic deficit that lasts more than 24 hours. Events lasting <24 hours are referred to as transient ischemic attacks (TIAs).
II. Pathophysiology
A. Etiology
Stroke is caused by occlusive vascular disease 85% of the time and hemorrhagic vascular disease 15% of the time.
B. Epidemiology
Risk factors for stroke include uncontrolled hypertension, hyperlipidemia, tobacco smoking, cardiac disease, coagulopathies, diabetes mellitus, and hormone therapy. Stroke is the third most common cause of death (1) and the most common acute neurologic event in the United States.
III. Evaluation (2,3)
A. History
Historical factors of note include:
  • Acute onset of symptoms
  • Unilateral change in motor control, vision, gait, strength, or sensation
  • Other neurologic disorders such as migraine, systemic lupus, vasculitis
  • Sudden onset of unusual headache
  • Presence of one or more risk factors
B. Physical examination
Physical findings include:
  • Alteration of mental status and/or consciousness
  • Slurred or inappropriate speech, aphasia
  • Hemiparalysis, hemiparesis
  • Altered sensation
  • Visual field defect, diplopia, nystagmus
  • Hypertension
  • Cardiac dysrhythmia
  • Dizziness, ataxia
  • Vascular tenderness to palpation, temporal and carotid arteries
C. Testing
Studies and laboratory tests include:
  • Computed tomography (CT) scan of the head to identify hemorrhage. Other imaging studies are undergoing clinical evaluation
  • Complete blood count, with platelet count, comprehensive chemistry panel, prothrombin time, partial thromboplastin time for underlying diseases and baseline if thrombolytic or anticoagulant therapy is anticipated
  • Special studies such as toxicology screen, antiphospholipid antibodies, protein S and C, antithrombin III, and others if indicated by history or physical examination
  • Electrocardiogram to help diagnose dysrhythmias or preceding myocardial infarction
  • Echocardiogram to visualize structural defects or mural thrombi. Transesophageal echocardiography may possibly be appropriate
  • Carotid/intracranial Doppler studies to find occlusive vascular disease or source of artery to artery emboli
IV. Diagnosis
A. Differential diagnosis
The differential diagnosis of stroke includes aberrant migraine, seizure disorder, metabolic disorders, psychogenic condition (hysterical conversion reaction, hyperventilation), and tumor with hemorrhage.
B. Clinical approach
With the availability of thrombolytic therapy, the urgency of making a rapid diagnosis has become more critical. Getting the patient to a medical care facility as quickly as possible is very important. A history and physical examination should be completed as quickly as is practical, with special attention to the neurological examination. Quantitative assessment of strength and function on the affected side should be documented for comparison with subsequent examinations. Clinical improvement in the first couple of hours would favor a TIA or a more localized stroke. After the initial history and physical examination, laboratory studies can be ordered and a noncontrast head CT scan can be obtained to rule out hemorrhage provided the patient is clinically stable enough. Appropriate interventions to control blood pressure, seizures, and cardiac dysrhythmias should proceed concomitantly with the evaluation.
References
1. CDC FASTATS: www.cdc.gov/nchs/fastats/stroke.htm, 2005
2. American Heart Association Stroke Outcome Classification. Executive summary. Circulation 1998:97:2474 - 2478.
3. Harrison's Online: Part 15. Neurological disorders. Section 2. Diseases of the Central Nervous system. Chapter 349. Cerebrovascular diseases.