Frequently Asked Questions

12. How is stroke diagnosed?

Doctors have several techniques and imaging tools to help diagnose stroke quickly and accurately. The first step in diagnosis is a short neurological examination, or an evaluation of the nervous system.

When a possible stroke patient arrives at a hospital, a health care professional, usually a doctor or nurse, will ask the patient or a companion what happened and when the symptoms began. Blood tests, an electrocardiogram, and a brain scan such as computed tomography (CT) or magnetic resonance imaging (MRI) will often be done.

MRI and CT are equally accurate for determining when hemorrhage is present. The benefit of MRI over a CT scan is more accurate and earlier diagnosis of ischemic stroke especially for smaller strokes and transient ischemic attacks (TIAs). Also, MRI can be more sensitive than CT for detecting other types of neurologic disorders that mimic the symptoms of stroke. However, MRI cannot be performed in patients with certain types of metallic or electronic implants, such as pacemakers for the heart.

Although increasingly used in the emergency diagnosis of stroke, MRI is not immediately available at all hours in most hospitals, where CT is used for acute stroke diagnosis. MRI typically takes longer to perform than CT, and therefore may not be the first choice when minutes count.