Multiple trials have confirmed the NINDS trial findings and established that management of AIS hinges on two basic questions: (1) Is this patient having AIS, and (2) is this patient a candidate to receive intravenous thrombolysis?

Is this patient having AIS? An acute, focal neurologic deficit is the hallmark of stroke. Major strokes involve both motor and sensory components. Symptoms may be sudden and maximal at onset (embolic) or intermittent and stuttering (thrombotic).

Findings in stroke syndromes depend on the territory of brain suffering infarction.

Anterior cerebral artery strokes produce contralateral sensory defects and contralateral weakness most profound in the lower extremities, often with urinary incontinence and dysarthria. Middle cerebral artery strokes produce contralateral sensory loss and weakness and homonymous hemianopsia. Lacunar strokes may produce varied combinations of weakness, sensory deficit, and ataxia.

Vertebrobasilar, or posterior circulation, strokes produce dizziness, vertigo, vomiting, and ataxia, and can cause limb weakness as well. The complaint of isolated dizziness is highly unlikely to be caused by a stroke.⁹

The differential diagnosis of AIS includes intracranial hemorrhage (ICH) or mass lesion, migraine, post-ictal paresis (Todd’s paralysis), CNS infection, multiple sclerosis, drug intoxication, hypoglycemia, and conversion disorder.¹⁰

Is the patient a candidate for rTPA? Time of onset of the focal neurologic deficit is the most important piece of history. The emergency physician should always attempt to answer the following question: When was the exact onset of stroke symptoms or, if this is unknown, when was the patient last observed to be asymptomatic? If onset of stroke symptoms occurred within 3 hours of evaluation, the goals of immediate management are different from cases that occur outside this window (also see the “Controversies” section below for further clarification).

When patients are seen in the emergency department within 3 hours of stroke symptoms, evaluation should be extremely rapid in a manner similar to trauma resuscitation, focusing on determining candidacy for rTPA. Findings particularly consistent with AIS include speech disturbance, and unilateral weakness, arm drift, and/or lower facial droop.¹¹