|How Are Strokes Diagnosed?
An initial examination and tests by doctors can confirm if a stroke has taken place, and if so, distinguish between an ischemic stroke and a hemorrhagic stroke. This differentiation is important because drugs used to treat ischemic patients can be life-threatening to those who suffered a hemorrhagic stroke. Treatment will only be started when the type of stroke has been established. Other tests will be able to identify the cause of the stroke and most of these tests will be performed within 24 hours of the stroke occurring. People who have suffered a mini stroke or have displayed other signs of stroke should also go through the same testing procedures as determining the underlying cause may help prevent a full-scale stroke in the near future. The doctor will usually start by asking the patient what happened and when symptoms began. He will try to establish the patient's stroke risk factors or any history of heart disease. He will then perform a quick physical and neurological exam to listen to the heart and arteries in the neck, looking for any abnormalities. Based on this information the physician will determine which tests are necessary. He may order one or more of the following procedures:
Brain Imaging: These tests give an internal picture (image) of the brain.
Electrical Tests: These study the brain's electrical activity.
Blood Flow Tests: Studies to show how well blood is flowing to the brain.
Brain Imaging Tests
A CT or CAT Scan (computed tomography) uses X-ray technique to create a cross sectional image of the brain to determine if a stroke has occurred and what type (ischemic or hemorrhagic). The scan takes about 20 minutes to complete. This is the standard test which most stroke patients undergo.
An MRI (magnetic resonance imaging) uses magnetic field technology to generate a 3D image of the brain. This can accurately determine how much brain tissue has been damaged by an ischemic stroke. It can also identify the presence, location and size of an aneurysm or arteriovenous malformation (see causes of stroke) which may have caused a hemorrhagic stroke. Usually the test takes about 30 minutes but newer ultrafast MRI's available at some stroke or chest pain centers take less than 15 minutes. Diagnosing and imaging a stroke quickly will improve the speed at which a patient receives treatment. Time is brain tissue - the quicker the treatment, the more of the brain function that will be saved.
This procedure uses X-ray technology (angiogram) to assess the blood vessels. It enables surgeons to detect a stroke and brain aneurysms or signs of bleeding (hemorrhaging) in the brain. As it is a more invasive test, it is only usually done once other tests have confirmed a stroke has taken place and stroke treatment has been started. It involves inserting a long thin tube (catheter) into an artery, usually in the groin, which is then guided through the body to the arteries in the neck (carotid arteries). Once the tube reaches the neck contrast dye is injected, doctors can monitor blood flow and detect any blockages or leaks. For more information about this procedure see heart angiography (image) and cardiac catheterization.
An EEG (electroencephalography) records the electrical impulses of the brain. Electrodes are placed on the scalp and detect the impulses which are then recorded on paper by an EEG machine. The intensity and duration of the impulses will provide information about the health of the brain and its function.
Evoked Response Test
This test is used to monitor the brain's reaction to environmental stimuli. Electrodes are attached to the scalp to monitor the brain response. A doctor will flash a light in front of you to check your visual response. A sound will be played in your ear to test your auditory (hearing) response and a nerve in the arm or leg will be stimulated electrically to test your body response. The responses will indicate any abnormal areas in the brain.
Blood Flow Testing
Vascular screening uses ultrasound technology to detect blockages in the arteries of the body. In relation to stroke; it is used to test the carotid arteries. This procedure can also be used to screen for early symptoms of coronary heart disease in people who are concerned about their personal heart attack risk factors or risk of stroke.
An ECG, or electrocardiogram (image) may be given to ischemic stroke patients to test for signs of atrial fibrillation (heart beat abnormalities). Alternatively (or in addition to) an echocardiogram may be performed. This is an ultrasound of the heart which is only done if the doctor suspects cardiac causes. A contrast echo (sometimes called a bubble study) can highlight if there a hole in the heart which allowed a blood clot to pass through the heart and reach the brain.
If doctors suspect that an irregular heartbeat may have caused a stroke they might ask the patient to wear a Holter Monitor (image) for 24 hours to assess the heart over a longer period of time. This is a portable device attached to electrodes on the body which record activity over a period of time. The results are later downloaded by a lab technician and analyzed. If the Holter Monitor fails to detect any irregularities an Event Monitor may be used - this can record for longer periods of time - weeks and even months.