When a patient has signs or symptoms of a stroke, a physician will promptly evaluate the patient’s medical history and obtain brain imaging tests such as a computed axial tomography (CAT) scan. The CAT scan can help the physician determine whether the patient is having a cerebral hemorrhage or an ischemic stroke caused by cerebral ischemia. This information determines the course of emergency treatment. The CAT scan may also help a physician locate the exact position of the brain damage.

Once the patient is stabilized, a complete evaluation of a patient who has had a stroke can take several days. Tests that may be performed during this time may include:

• Physical examination, during which functioning of the carotid arteries (the arteries that carry blood from the heart to the brain) will be examined with a stethoscope. If a physician hears an abnormal sound (a carotid bruit), it may indicate atherosclerosis (hardening of the arteries) or carotid artery disease – conditions that increase the risk of stroke.
  
  
• A carotid ultrasound is a painless technique that uses high-frequency sound waves to identify the presence of plaque in the carotid arteries.
  
  
• Magnetic resonance angiography (MRA) is a diagnostic imaging test used to assess the degree of blockage in arteries in and around the brain. The MRA is a variation of the magnetic resonance imaging (MRI) scan, which is also very important in diagnosing a stroke. MRA is used specifically for the arteries. Magnetic resonance venography (MRV) is a related blood vessel study that is more specific for veins in and around the brain. Radionuclide tests (such as PET scan) may also be performed to image the brain to determine the extent of damage.

• An electrocardiogram (EKG) may be performed to identify any cardiac problems that may have led to the stroke, such as a prior heart attack. Patients who have had a heart attack in the past are at increased risk of blood clots forming in the heart, which could trigger a stroke. Patients are also at increased risk of developing a stroke if arrhythmias (heart rhythm disorders) such as atrial fibrillation are present. Finally, because an ischemic stroke and a heart attack may have the same underlying cause (e.g., atherosclerosis), a physician may use an EKG to look for additional signs of heart disease.
  
  
• Blood tests, including a complete blood count (CBC) and a lipid profile (cholesterol test) may also be performed. These tests may help identify whether a patient has certain risk factors associated with stroke, such as high cholesterol.

Some additional tests may be performed to assess overall brain function, as measured by electrical activity. These tests can reveal how much neurological damage was done as a result of the stroke. Among the most common of these tests are:

• Electroencephalogram (EEG). During this painless test, small metal electrodes are attached to the scalp. The electrodes are connected by wires (leads) to an electroencephalograph machine that charts the electrical activity of the brain.
  
  
• Evoked potential study. A test of the nervous system that can measure the brain's response to sight, hearing and touch stimuli.