Diagnosis

Other Techniques. Other imaging tests, including positron-emission tomography (PET) and single photon-emission computed tomography (SPECT), may also help the doctor identify injuries caused by the stroke.

Heart Evaluation

Electrocardiogram (ECG). A heart evaluation using an electrocardiogram (ECG) is important in any patient with a stroke or suspected stroke. An ECG records the electrical current in the heart muscle.

Echocardiogram. An echocardiogram uses ultrasound to view the chambers and valves of the heart. It is generally useful for stroke patients to identify blood clots or risk factors for blood clots that can travel to the brain and cause stroke. There two are types:

• Transthoracic echocardiograms (TTE) view the heart through the chest. It is noninvasive and is the standard approach.
• Transesophageal echocardiogram (TEE) examines the heart using an ultrasound tube that the patient literally swallows and passes down the throat. It is uncomfortable and requires sedation. It is typically used to obtain more accurate images of the heart if a TTE has suggested abnormalities, such as atrial fibrillation or patent foramen ovale (PFO).

Other Tests

Blood Tests. Several blood tests may help predict the risk for a stroke and determine the severity and complications of an existing stroke.

• Specific blood tests are important to determine clotting times, to check electrolytes (potassium, calcium, sodium), and to measure factors indicating liver or kidney problems. Kidney tests measure blood proteins that are filtered through the kidneys. These proteins include creatinine and blood urea nitrogen (BUN). A more recent type of kidney test measures the protein cystatin C. Recent research suggests that the cystatin C kidney test may be better at predicting cardiovascular risks in elderly patients.
• Blood sugar (glucose) levels are measured. Hyperglycemia (high levels) may indicate a worse outcome for some strokes (although not hemorrhagic or lacunar strokes). Hypoglycemia (low levels) is a common complication of diabetes treatments, and its symptoms may mimic those of a stroke.
• A new blood test, the PLAC test, was approved in 2005 to help diagnose people at increased risk for ischemic stroke. The PLAC test measures an enzyme called lipoprotein-associated phospholipase A2 (Lp-PLA2). Patients with high levels of this protein have twice the risk for ischemic stroke as patients with normal levels.

Examination of Spinal Fluid. If the CT scan is negative but the doctor still suspects a subarachnoid hemorrhagic stroke, a spinal tap may be performed. Spinal fluid containing significant amounts of blood will usually confirm a hemorrhagic stroke.