Stroke (cont.)

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How is a stroke diagnosed?

A stroke is a medical emergency. Anyone suspected of having a stroke should be taken to a medical facility immediately for evaluation and treatment. Initially, the doctor takes a medical history from the patient, if possible, or from others familiar with the patient if they are available. Important questions include what the symptoms were, when they began, and if they were getting better, worse or staying the same. Past medical history adds important information looking for risk factors for stroke and for medications that can cause bleeding (for example, warfarin [Coumadin], clopidogrel [Plavix], prasugrel [Effient], apixaban [Eliquis], and rivaroxaban [Xarelto]).

Physical examination is key in confirming the parts of the body that have stopped functioning and may help determine what part of the brain has lost its blood supply. If available, a neurologist, a doctor specializing in disorders of the nervous system and diseases of the brain, can assist in the diagnosis and management of stroke patients. Hospitals may use telemedicine to have the neurologist "examine" the patient from afar, if one is not available locally.

Just because a person has slurred speech or weakness on one side of the body does not necessarily signal the occurrence of a stroke. There are many other possibilities that can be responsible for these symptoms. Other conditions that can mimic a stroke include:

  • brain tumors,
  • brain abscess (a collection of pus in the brain caused by bacteria or a fungus),
  • migraine headache,
  • bleeding in the brain either spontaneously or from trauma,
  • meningitis or encephalitis,
  • an overdose of certain medications, or
  • an electrolyte imbalance in the body. Abnormal concentrations (too high or too low) of sodium, calcium, or glucose in the body may also cause changes in the nervous system that can mimic a stroke.

During the acute stroke evaluation, many things will occur at the same time. As the physician is taking the history and performing the physical examination, nursing staff will begin monitoring the patient's vital signs, performing blood tests, and performing an electrocardiogram (EKG or ECG).

Part of the physical examination that is becoming standardized is the use of a stroke scale. The American Heart Association has published a guide to the examination of the nervous system to help health care practitioners determine the severity of a stroke and whether aggressive intervention may be warranted.

There is a narrow time frame to intervene in an acute stroke with medications to reverse the loss of blood supply to part of the brain (please see TPA below). The patient needs to be appropriately evaluated and stabilized before any clot-busting drugs can be potentially utilized.

Computerized tomography: In order to help determine the cause of a suspected stroke, a special X-ray test called a CT scan of the brain is often performed. A CT scan is used to look for bleeding or masses within the brain that may cause symptoms that mimic a stroke, but are not treated by thrombolytic therapy with TPA.

MRI scan: Magnetic resonance imaging (MRI) uses magnetic waves rather than X-rays to image the brain. The MRI images are much more detailed than those from CT, but due to the length of time to do the test and lack of availability of the machines in many hospitals, is not a first-line test in stroke. While a CT scan may be completed within a few minutes, an MRI may take much longer. An MRI may be performed later in the course of patient care if finer details are required for further medical decision making. People with certain medical devices (for example, pacemakers) or other metals within their body, cannot be subjected to the powerful magnetic field of an MRI.

Other methods of MRI technology: An MRI scan can also be used to specifically view the blood vessels non-invasively (without using tubes or injections); the procedure is called an MRA (magnetic resonance angiogram). Another MRI method called diffusion weighted imaging (DWI) is being offered in some medical centers. This technique can detect the area of abnormality minutes after the blood flow to a part of the brain has ceased, whereas a conventional MRI may not detect a stroke until up to 6 hours after it has started, and a CT scan sometimes cannot detect it until it is 12 to 24 hours old. Again, this is not a first-line test in the evaluation of a stroke patient, when time is of the essence.

Computerized tomography with angiography: Using dye that is injected into a vein in the arm, images of the blood vessels in the brain can give information regarding aneurysms or arteriovenous malformations. Moreover, other abnormalities of brain blood flow may be evaluated. With faster machines and better technology, CT angiography may be done at the same time as the initial CT scan to look for a blood clot within an artery in the brain.

CT and MRI images often require a radiologist to interpret the results.

Conventional angiogram: An angiogram is another test that is sometimes used to view the blood vessels. A long catheter tube is inserted into an artery in the groin or arm and threaded into the arteries of the brain. Dye is injected while X-rays are taken and information can be obtained about blood flow in the brain. The decision to perform CT angiography versus conventional angiography depends upon a patient's specific situation and the technical capabilities of the hospital.

Carotid Doppler ultrasound: A carotid Doppler ultrasound is a non-invasive test that uses sound waves to look for narrowing or stenosis and decreased blood flow in the carotid arteries (the major arteries in the front of the neck that supply blood to the brain).

Heart tests: Certain tests to evaluate heart function are often performed in stroke patients to search for the source of an embolism. Electrocardiograms (EKG or ECG) may be used to detect abnormal heart rhythms like atrial fibrillation that are associated with embolic stroke.

Ambulatory rhythm monitoring may be considered if the patient complains of palpitations or passing out episodes (syncope) and the doctor cannot find reason for it on the EKG. The patient can wear a Holter monitor for 1 to 2 days and sometimes longer looking for a potential electrical conduction problem with the heart.

Echocardiograms or ultrasounds of the heart can help evaluate the structure and function of the heart including the heart muscle, valves, and the motion of the heart chamber when the heart beats. As well, specifically for stroke patients, this test may be able to find blood clots within the heart and the presence of a patent foramen ovale, both potential causes of stroke.

Blood tests: In the acute situation, when the patient is in the midst of a stroke, blood tests are done to check for anemia, kidney and liver function, electrolyte abnormalities, and blood clotting function.

In other situations, when time is not of the essence, similar blood tests may be done. In addition, screening tests for inflammation may be considered including an ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein). These are non-specific tests that may give direction to medical care.

Medically Reviewed by a Doctor on 4/10/2013

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