It is important to determine precisely the temporal course and physical distribution of all neurologic symptoms. The symptoms of ischemic stroke have an all at once onset but may be either transient or permanent. TIAs due to stenosis are characteristically short in duration and highly stereotyped, often occurring in clusters. Artery-to-artery embolic TIAs may also be stereotypical and are usually more long lasting. Cardioembolic TIAs tend to be quite long lasting (from 1 to several hours), do not recur frequently, and may present with symptoms from different vascular territories in separate attacks. Vascular dissections may be neurologically asymptomatic, and may become symptomatic days to weeks after.

The combination of amaurosis fugax and ipsilateral focal neurologic signs, as those listed in the preceding text, is highly suggestive of carotid disease. Alternating neurologic symptoms, such as left then right hemiparesis, suggest vertebrobasilar disease, cardiac embolism, or diffuse vascular disease.

A number of entities can resemble TIA or stroke clinically. Migraine presents with a march of neurologic symptoms that last 5-20 minutes. Seizures present with a rapid sequence of neurologic signs that last for less than a minute. Occasionally, primary and metastatic brain tumors produce transient focal neurologic findings. Supratentorial meningioma and arteriovenous malformations (AVMs) can also mimic TIAs. Less common etiologies of strokelike symptoms include subacute subdural hematoma, especially in elderly patients, and amyloid angiopathy (AA), which usually causes lobar hemorrhages but can also present with recurrent episodes of sensory loss and ischemic infarctions.

Systemic disease entities that can mimic ischemic stroke include mitochondrial myopathy (e.g., MELAS), hypertensive encephalopathy, symptomatic hypoglycemia, and hyperventilation.

The most effective treatment is intravenous (IV) or intra-arterial (IA) thrombolysis which requires rapid diagnosis and introduction of the thrombolytic agent within 3-6 hours. The primary goal is to administer thrombolytics as quickly as possible; time is, neuron’.

When evaluating a patient within a time window feasible for thrombolytic therapy, a standard noncontrast computed tomography (CT) is obtained to exclude hemorrhage, tumor, or other structural lesions which can preclude thrombolytic therapy. The CT findings in stroke evolve with time. Within the first 6 hours, early signs of infarction can be identified only in 30-40% of cases. With time, infarcts become more conspicuous. After 24 hours most infarcts are visible. Posterior fossa and brain stem infarcts are difficult to identify on CT owing to their small size and prominent beam hardening artifacts.

Standard evaluation includes noncontrast head CT, which must be reviewed in parenchymal, stroke, and subdural windows. Computed tomographic angiography (CTA) can be obtained to evaluate the intra- and extracranial cerebral vessels. CT perfusion is a robust technique that can be performed immediately after CTA. CT perfusion is currently limited—in that one cannot image the entire brain.