Tests - Stroke Warning Signs
When someone has shown symptoms of a stroke or a TIA (transient ischemic attack), a doctor will gather information and make a diagnosis. He or she will review the events that have occurred and will:
- get a medical history
- do a physical and neurological examination
- have certain laboratory (blood) tests done
- get a CT or MRI scan of the patient
- study the results of other diagnostic tests that might be needed
Diagnostic tests examine how the brain looks, works and gets its blood supply. They can outline the injured brain area. Most of them are safe and painless. Diagnostic tests fall into three categories:
Imaging tests give a picture of the brain similar to X-rays. This is usually done with a CT scan of the head. It can also be done using MRI (magnetic resonance imaging), which uses a large magnetic field to produce an image of the brain. Like the CT scan, it shows the location and extent of brain injury. The image produced by MRI is sharper and more detailed than a CT scan so it's often used to diagnose small, deep injuries.
Electrical tests record the electrical impulses of the brain. Two basic tests, EEG and Evoked Response, show the brain's electrical activity. In an EEG (electroencephalogram), small metal discs (electrodes) are placed on a person's scalp to pick up electrical impulses. These electrical signals are printed out as brain waves. An Evoked Response test measures how the brain handles different sensory information. Electrodes record electrical impulses related to hearing, body sensation or vision.
Blood flow tests show any problem that may cause changes in blood flow to the brain. Several blood flow tests exist; most use ultrasound technology. A probe is placed over the suspect artery—especially arteries in the neck (carotid) or at the base of the skull (vertebral)—and the amount of blood flow is determined. Examples of blood flow tests are B-mode imaging, Doppler testing and duplex scanning. These tests give detailed information about the condition of arteries.
Another blood flow test is a medical procedure called angiography (arteriography or arteriogram). This test is like a cardiac catheterization, only the catheter is placed in the arteries of the brain rather than in the arteries of the heart. In this test, a special dye is injected into the blood vessels and an X-ray is taken. Angiography gives a picture of the blood flow through the vessels and allows the size and location of blockages to be evaluated. This test can be especially valuable in diagnosing aneurysms and malformed blood vessels and providing information before surgery.