Master the board step 3

Master the Boards: USMLE Step 3
Answer: B. Prior to administering thrombolytics or any anticoagulation, you need to
rule out hemorrhagic stroke, which is a contraindication to thrombolytics. You cannot
even give aspirin without doing a head CT first. Thrombolytics are indicated within the
first 3 hours of the onset of the symptoms of a stroke. Remember, 20 percent of strokes
are hemorrhagic. You do not need contrast to visualize blood; contrast is used to detect
cancer or infection, such as an abscess.
Arterial Lesions and Symptoms
Identifying or localizing a lesion based on characteristic symptoms likely will
be important during the exam.
Cerebral Artery
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
Vertebrobasilar artery
Posterior inferior cerebellar artery
Lacunar infarct
Ophthalmic artery
Symptoms
• Profound lower extremity weakness (contralateral in the case of unilateral
arterial occlusion)
• Mild upper extremity weakness (contralateral in the case of unilateral arterial
occlusion)
• Personality changes or psychiatric disturbance
• Urinary incontinence
• Profound upper extremity weakness (contralateral in the case of unilateral
arterial occlusion)
• Aphasia
• Apraxia/neglect
• The eyes deviate toward the side of the lesion.
• Contralateral homonymous hemianopsia, with macular sparing
• Prosopagnosia (inability to recognize faces)
• Vertigo
• Nausea and vomiting
• May be described as a “drop attack,” loss of consciousness
• Vertical nystagmus
• Dysarthria and dystonia
• Sensory changes in face and scalp
• Ataxia
• Bilateral findings
• Ipsilateral face
• Contralateral body
• Vertigo and Horner’s syndrome
• There must be an absence of cortical deficits.
• Ataxia
• Parkinsonian signs
• Sensory deficits
• Hemiparesis (most notable in the face)
• Possible bulbar signs
• Amaurosis fugax
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