Seizure (cont.)
Eclampsia
Eclampsia is a life-threatening condition that can
develop in pregnant women.
Its symptoms include sudden elevations of blood pressure and seizures. Pregnant
women who develop unexpected seizures should be rushed to a hospital
immediately. Eclampsia can be treated in a hospital setting and usually does not
result in additional seizures or epilepsy once the
pregnancy is over.
How is Epilepsy Diagnosed?
Doctors have developed a number of different tests to determine whether a
person has epilepsy and, if so, what kind of seizures the person has. In some
cases, people may have symptoms that look very much like a seizure but in fact
are nonepileptic events caused by other disorders. Even doctors may not be able
to tell the difference between these disorders and epilepsy without close
observation and intensive testing.
EEG Monitoring
An EEG records brain waves detected by electrodes placed on the scalp. This
is the most common diagnostic test for epilepsy and can detect abnormalities in
the brain's electrical activity. People with epilepsy frequently have changes in
their normal pattern of brain waves, even when they are not experiencing a
seizure. While this type of test can be very useful in diagnosing epilepsy, it
is not foolproof. Some people continue to show normal brain wave patterns even
after they have experienced a seizure. In other cases, the unusual brain waves
are generated deep in the brain where the EEG is unable to detect them. Many
people who do not have epilepsy also show some unusual brain activity on an EEG.
Whenever possible, an EEG should be performed within 24 hours of a patient's
first seizure. Ideally, EEGs should be performed while the patient is sleeping
as well as when he or she is awake, because brain activity during sleep is often
quite different than at other times.
Video monitoring is often used in conjunction with EEG to
determine the nature of a person's seizures. It also can be used in some cases to rule out
other disorders such as cardiac arrythmia or narcolepsy that may look like
epilepsy.
Brain Scans
One of the most important ways of diagnosing epilepsy is
through the use of brain scans. The most commonly used brain scans include CT
(computed tomography), PET (positron emission tomography) and
MRI (magnetic resonance
imaging). CT and MRI scans reveal the structure of the brain, which can be
useful for identifying brain tumors, cysts, and other structural abnormalities.
PET and an adapted kind of MRI called functional MRI (fMRI) can be used to
monitor the brain's activity and detect abnormalities in how it works. SPECT (single photon
emission computed tomography) is a relatively new kind of brain scan that is sometimes used to locate seizure foci in the brain.
In some cases, doctors may use an experimental type of brain scan called a
magnetoencephalogram, or MEG. MEG detects the magnetic signals generated by
neurons to allow doctors to monitor brain activity at different points in the
brain over time, revealing different brain functions. While MEG is similar in
concept to EEG, it does not require electrodes and it can detect signals from
deeper in the brain than an EEG. Doctors also are experimenting with brain scans
called magnetic resonance spectroscopy (MRS) that can detect abnormalities in
the brain's biochemical processes, and with near-infrared spectroscopy, a
technique that can detect oxygen levels in brain tissue.
Medical History
Taking a detailed medical history, including symptoms and
duration of the seizures, is still one of the best methods available to
determine if a person has epilepsy and what kind of seizures he or she has. The
doctor will ask questions about the seizures and any past illnesses or other
symptoms a person may have had. Since people who have suffered a seizure often
do not remember what happened, caregivers' accounts of the seizure are vital to this evaluation.
Blood Tests
Doctors often take blood samples for testing, particularly when they are
examining a child. These blood samples are often screened for metabolic or
genetic disorders that may be associated with the seizures. They also may be
used to check for underlying problems such as infections, lead poisoning,
anemia, and diabetes that may be causing or triggering the seizures.
Developmental, Neurological, and Behavioral Tests
Doctors often use tests devised to measure motor
abilities, behavior, and
intellectual capacity as a way to determine how the epilepsy is affecting that
person. These tests also can provide clues about what kind of epilepsy the
person has.
Next: Can Epilepsy be Prevented? »
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