Diagnosis of Stroke
Prompt diagnosis and immediate intervention are key to preventing death and increasing the chance for recovery from a stroke. Strokes are diagnosed through physical and neurological examinations, laboratory tests and brain imaging studies.
Getting a diagnosis at a hospital for stroke.
While you are in the hospital, there are procedures that may be done to help diagnose a stroke and to find its source(s). The following is a brief overview of some of the most commonly ordered:
CT or CAT scan (Computed Tomography Scan): This is a special type of x-ray that is capable of taking pictures of the brain. In some case, dye (contrast material) is used. The CAT scan is helpful in diagnosing strokes or other abnormalities of the brain. During this test, you will need to lie on a X-ray table. The table then is moved into the tube like opening of the scanner. There are usually no restrictions before or after the test. The test is painless and usually takes about 1/2 hour. Make sure that you tell the nurse or doctor of any allergies because of possible reaction to the dye. Sometimes a stroke cannot be seen in the first 24 hours in a CAT scan and it may be necessary to repeat the scan the following day.
MRI (Magnetic Resonance Imaging): This test uses magnetic field and radiowaves (not x-rays) to provide a picture of the brain. An MRI gives great detail. During this painless test, you will lie on a narrow bed that slides into the MRI scanner. It takes about 20-45 minutes. If you have any metal objects in your body, such as joint replacements and surgical clips pacemakers, inform the staff. If you have a pacemaker, you cannot have this test. If you have claustrophobia, please let the staff know. Your doctor may prescribe a medication to be given before the test to help you relax.
MRA (Magnetic Resonance Angiography): This non-invasive test is like an MRI. The MRA takes pictures of the blood vessels, especially those supplying the brain. It may show the narrowing or defects in the blood vessels which help explain the source of the stroke. Unlike Angiogram, no dye is injected or used in this procedure.
Carotid Duplex: This is an ultrasound study of the carotid arteries which are located in front of the neck. A probe which sends sound waves is placed over the neck area for this test. This, non-invasive test, is the most commonly used imaging test for the carotid arteries.
Transesophageal Echocardiogram (TEE): This test is a specialized type of heart examination in which sound wave (ultrasound) images from a device (transducer) placed in the esophagus behind the heart are recorded. After the throat is numbed with a local anesthetic, the transducer mounted on the tip of a lighted tube is inserted into the esophagus through the mouth. It then sends and receives waves reflected from the heart. The reflected sound waves are processed by a special computer that shows an image of the heart on a video monitor. TEE gives very high quality images of the heart that cannot be obtained via the traditional transthoracic echocardiogram. To avoid vomiting and aspiration, you will not be allowed to eat or drink before and immediately after the procedure. Once the procedure is done, the nurse needs to evaluate your gag and swallowing reflexes to make sure these are back before you will be allowed to eat or drink.
Transcranial Doppler (TCD): This study examines the size of the blood vessels in the brain and the direction of blood flow. In this test the person will need to lie on a table or in bed. The technician will apply gel in front of your ears, over your eyes or on the back of your head. You will hear a swishing sound as the probe senses the blood flowing through your blood vessels. The test takes about 30 minutes and is painless and noninvasive. You will be able to resume normal activities after the test.
Electroencephalogram (EEG): This test records and measures patterns of electrical impulses from the brain. Tiny electrodes are placed on the scalp and a recording is made. It is very important to stay still while the recording is being done. Brain waves slow in the area of the stroke and will help doctors determine the area of damage in the brain. However, this is not a definitive test for a stroke.
Cerebral Angiogram or Arteriogram: This is a special x-ray of the blood vessels of the brain taken after injecting a dye to make the vessels more visible. The dye is injected through a catheter (a long thin tube) that is inserted into an artery (usually in the groin area). The procedure takes 30-60 minutes and is useful in determining blockage and abnormalities in the blood vessels of the brain.