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How is epilepsy diagnosed?
The evaluation of patients with epilepsy is aimed at determining the type of
seizure (epileptic versus nonepileptic) and its cause, since various seizure
types respond best to specific treatments. The diagnosis is based on the
following:
- The patient's medical history, including any family history of
seizures, associated medical conditions, and current medications. Some
important questions you 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?
- Others who have often seen you before, during, and after
seizures, such as family and close friends, should be present to provide
details of your seizures if they involve loss of consciousness.
- A complete physical and neurological examination of muscle
strength, reflexes, eyesight, hearing, and ability to detect various
sensations are tested so that your doctors can better understand the cause of
your seizures
- 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)
*The most important part of the evaluation 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 minutes of brain waves (however, the
routine EEG procedure takes about 90 minutes). Because 20 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. Prolonged EEG-video monitoring is an even better 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.
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