Diagnosis of a stroke begins with a prompt review of the patient’s medical history, followed by tests such as CAT scan (computed axial tomography).

The CAT scan helps the physician determine whether the patient is experiencing a cerebral ischemia (a stroke caused by the blockage of an artery) or a cerebral hemorrhage (a stroke caused by the rupture of an artery), and assists in identifying the exact position of the damage. This information enables the physician to select a course of emergency treatment.

After the patient is stabilized the physician will perform a complete medical evaluation. Evaluation of a stroke patient may take several days and can include:

• Physical examination. The physician uses a stethoscope to examine the carotid artery in the neck. If the physician hears an abnormal sound (a carotid bruit) during examination, there is a greater chance of finding atherosclerosis (a condition characterized by excess plaque on the inner arterial walls) or cerebrovascular disease. Diabetic patients have an increased risk of developing both of these contributors to stroke.
  
  
• Carotid ultrasound, or duplex scanning. This test uses high-frequency sound waves to assess the presence of plaque in the carotid artery. Plaque accumulation can result in atherosclerosis, a diabetic complication and major stroke risk factor.
  
  
• Magnetic resonance angiography (MRA). An MRA is another noninvasive diagnostic test used to help determine the degree of blockage in the carotid arteries. This test is a variation of magnetic resonance imaging (MRI). An MRI can also be useful in diagnosing a stroke, particularly a variation known as functional MRI, which produces real-time images of blood flow to parts of the brain.
  
  
• Electrocardiogram (EKG or ECG). This test is used to identify any underlying cardiac problems that may have contributed to the stroke, such as a prior heart attack. Cardiovascular disease is the most serious and common complication of diabetes. In addition, diabetic patients are more likely to suffer cardiovascular complications than non-diabetics.
  
  
• Blood tests. These tests may include a complete blood count (CBC) and a cholesterol test (lipid profile).

The physician may also recommend tests that use electrical activity to assess overall brain functioning. These tests can reveal how much neurological damage resulted from the stroke. The most common of these tests include:

• Electroencephalogram (EEG). During this painless procedure, small metal devices (electrodes) are attached to the scalp. The electrodes are connected by wires (leads) to an electroencephalograph machine that charts the brain’s electrical activity.
  
  
• Evoked-potential study. This test measures the brain’s response to sight, hearing and touch.