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Diagnosing Epilepsy

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    Evaluating patients with epilepsy is aimed at determining what type of seizures they are having (epileptic versus nonepileptic) and their cause. Various seizure types respond best to specific treatments. The diagnosis of epilepsy is based on:

    • The patient's medical history, including any family history of seizures, associated medical conditions, and current medications. Also helpful to the doctor is the input of people who have witnessed a patient's seizures, especially if there is a loss of consciousness. Some important questions a patient will be asked include:
      • At what age did the seizures begin?
      • What circumstances surrounded your first seizure?
      • What factors seem to bring on the seizures?
      • What do you feel before, during, and after the seizures?
      • How long do the seizures last?
      • Have you been treated for epilepsy before?
      • What medications were prescribed and in what dosages?
      • Was the treatment effective?

    Tests that will be performed include:

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    • A complete physical and neurological exam of muscle strength, reflexes, eyesight, hearing, and ability to detect various sensations
    • An electroencephalogram (EEG) test, which measures electrical impulses in the brain*
    • Imaging studies of the brain, such as those provided by magnetic resonance imaging (MRI)
    • Blood tests to measure red and white blood cell counts, blood sugar, blood calcium, and electrolyte levels; and to evaluate liver and kidney function; blood tests help rule out the presence of other illnesses.
    • Other tests, as needed, including magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single photon emission computed tomography (SPECT)

    *An important part of the diagnostic process is the electroencephalogram (EEG), because it is the only test that directly detects electrical activity in the brain, and seizures are defined by abnormal electrical activity in the brain. During an EEG, electrodes (small metal disks) are attached to specific locations on your head. The electrodes are attached to a monitor to record the brain's electrical activity. The EEG is useful not only to confirm a diagnosis of epilepsy, but also to determine the type of epilepsy.

    A routine EEG only records about 20-30 minutes of brain waves (however, the entire EEG procedure takes about 90 minutes). Because 30 minutes is such a short amount of time, the results of routine EEG studies are often normal, even in people known to have epilepsy. Therefore, prolonged EEG monitoring may be necessary. Some monitors allow the patient to stay at home and continue his or her normal activities.

    Prolonged EEG-video monitoring is another diagnostic method. During this type of monitoring, an EEG monitors the brain's activity and cameras videotape body movements and behavior during a seizure. Prolonged monitoring often requires the patient to spend time in a special hospital facility for several days. Prolonged EEG-video monitoring is the only definitive way to diagnose epilepsy.

    WebMD Medical Reference

    Reviewed by Richard Senelick, MD on June 01, 2012
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