Diagnosis

Ruling Out Other Disorders. In most cases of stroke, the diagnosis is evident although a number of conditions may cause similar symptoms. These include seizures, infections that cause mental confusion, syncope (fainting), hypoglycemia, and brain tumors.

Imaging Tests Used for Stroke and Risk Factors for Stroke

Computed Tomography. A computed tomography (CT) scan is the standard imaging test for the brain. The test is performed as early as possible. It is essential in ruling out hemorrhagic stroke and can accurately diagnose about 95% of hemorrhagic strokes. The full evidence of an ischemic stroke will usually not show up on a CT scan for hours to days. A CT scan, however, may be useful in identifying early signs of injury from ischemic strokes that could effect the decision to use thrombolytics (clot-busting drugs). High-speed CT scans (called helical or spiral CTs), which quickly identify ischemic strokes and the location of the blockage, are now available in many centers.

Magnetic Resonance Imaging (MRI). A standard magnetic resonance imaging (MRI) scan is able to evaluate the blood vessels and the brain's circulation and determine injuries from ischemic strokes. It is not very useful in the first hours of a stroke, however, since it tends to show abnormalities that may not be significant. Advanced MRI techniques, such as diffusion- or perfusion-weighted MRIs, may be sensitive enough to identify injured areas within minutes of symptoms. MRIs cannot be used by patients with pacemakers or metal implants, or who are claustrophobic.

Ultrasound. Ultrasound may be used in different circumstances. This imaging technique is painless and noninvasive.

• Carotid ultrasound (also called Doppler or duplex sonography) can determine blockage in the carotid arteries that could lead to or be causing a stroke.
• Transcranial duplex sonography can identify blockage in large arteries in stroke patients and to monitor the effects of thrombolytic therapy.

1. Cerebral Angiography. Cerebral angiography is an invasive procedure that may be used for patients with TIAs who require surgery. It can also detect aneurysms and monitor thrombolytic therapy. It requires the insertion of a catheter into the groin, which is then threaded up through the arteries to the base of the carotid artery. At this point a dye is injected, and x-rays, CTs, or MRI scans determine the location and extent of the narrowing, or stenosis, of the artery. In people with TIAs the risk of stroke itself increases using this technique, particularly in elderly people with diabetes.