Focal and Generalized Seizures

The first panel of this illustration shows a healthy brain with a normal wave pattern and no seizure activity.

The second panel shows the wave pattern of a person with a focal-seizure disorder and where in the brain it occurs. A focal seizure begins in 1 side of the brain.

The third panel shows the wave pattern of a generalized seizure and where in the brain it occurs. A generalized seizure begins in both sides of the brain.

Note: Seizures, by definition, last at least 10 seconds; abnormal EEG patterns shown here would be more prolonged.