Healthy Living and Fitness

Illness Care: Stroke

Diagnosis

The first step in diagnosis is a short neurological examination. When a possible stroke patient arrives at a hospital, a health care professional, usually a doctor or nurse, will ask the patient or a companion what happened and when the symptoms began. They are likely to have a brain scan which will usually show the site of the deficit.
A variety of imaging devices are used to evaluate stroke patients. The most widely used imaging procedure is the computed tomography (CT) scan. Also known as a CAT scan or computed axial tomography, CT creates a series of cross-sectional images of the head and brain. Because it is readily available at all hours at most major hospitals and produces images quickly, CT is the preferred diagnostic technique for acute stroke. CT also has unique diagnostic benefits. It will quickly rule out a haemorrhage, can occasionally show a tumour that might mimic a stroke, and may even show evidence of early infarction (a sudden loss of blood supply to tissue). Infarctions generally show up on a CT scan about 6 to 8 hours after the start of stroke symptoms.

If a stroke is caused by haemorrhage, a CT can show evidence of bleeding into the brain almost immediately after stroke symptoms appear. Haemorrhage is the primary reason for avoiding certain drug treatments for stroke, such as thrombolytic therapy, the only proven acute stroke therapy for ischemic stroke. Thrombolytic therapy cannot be used until the doctor can confidently diagnose the patient as suffering from an ischemic stroke because this treatment might increase bleeding and could make a hemorrhagic stroke worse.

Another imaging device used for stroke patients is the magnetic resonance imaging (MRI) scan. MRI uses magnetic fields to detect subtle changes in brain tissue content. One effect of stroke is an increase of water content in the cells of brain tissue. MRI can detect this as soon as a few hours after the onset of stroke. The benefit of MRI over CT imaging is that MRI is better able to detect small infarcts soon after stroke onset. Unfortunately, not every hospital has access to an MRI device and the procedure is time-consuming and expensive. It also is not as accurate in determining when haemorrhage is present. Finally, because MRI takes longer to perform than CT, it should not be used if it delays treatment

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Other investigations are also carried out. An ECG (heart tracing) will be done to look for an irregular heart beat. Blood tests to look at the level of cholesterol, the degree of blood thickening, the blood sugar and blood electrolyte balance will usually be made. The blood pressure is always measured. To help judge the severity of the stroke doctors ask the patient to answer questions and to perform several physical and mental tests. Occasionally a test of the blood flow in the carotid arteries which supply the brain is done since a small but significant number of strokes are due to a narrowing of one of these arteries.

 

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