Magnetoencephalography in Absence Seizures

Background:

- An absence seizure is a type of seizure that usually begins in childhood and goes away
by early adulthood. Scientists do not yet know where absence seizures begin in the
brain. Some evidence suggests that these seizures begin in the thalamus, a structure
deep in the brain, but other studies suggest that they begin in the frontal cortex, at
the front part of the brain.

- Magnetoencephalography is a type of brain scanning procedure that is useful in
determining information about what happens to the brain during epileptic seizures.
Understanding where absence seizures come from may help doctors find new treatments for
them.

Objectives:

- To gain a better understanding of which parts of the brain are affected in absence
seizures.

Eligibility:

- Patients 7 to 35 years of age who have been diagnosed with absence seizures.

Design:

- Procedures are for research purposes only, not to diagnose or treat a particular
medical condition.

- Two outpatient visits to the National Institutes of Health Clinical Center: evaluation
and scanning.

- Researchers will evaluate potential participants with a medical history, physical
examination, and electroencephalography (EEG). These tests will be performed under
another protocol, 01-N-0139.

- Patients will undergo magnetoencephalography (MEG) and magnetic resonance imaging (MRI)
of the brain. The study procedures will be performed one time; however, an MEG or MRI
scan may need to be repeated for technical reasons. Researchers will not do more than
two MEG or MRI scans.

- The MEG will record very small magnetic field changes produced by the activity of the
brain. An EEG will be recorded at the same time as the MEG.

- The MRI will use a magnetic field to take pictures of the inside of the brain.

- The MEG will take 3 hours to complete (2 hours for preparation, 1 hour in the scanner).
The MRI will take approximately 1 hour.