1. Spike, generalized. Note the high amplitude, and the aftergoing background suppression and slow wave.

2. 3 Hz spike-wave complexes (SWC), generalized. This pattern is very monomorphic, with a maximum (shown here by a phase reversal) frontally, typically at F3/F4. This is typical of idiopathic (i.e., genetic) generalized epilepsies, such as absence epilepsy. The 3 Hz SWC is often faster (4-5 Hz) at onset, as shown here.

3. Sharp waves, multifocal. Sharp waves are seen at T4, T6, T5 and F3 on this 9 sec segment. With other findings, this is often seen in the symptomatic/ cryptogenic epilepsies of the Lennox-Gastaut type.

4. Slow spike-wave complexes. In addition to being slower, this is also less monomorphic than the 3 Hz SWC. With other findings, this is often seen in the symptomatic/ cryptogenic epilepsies of the Lennox-Gastaut type.

5. Hypsarrhythmia. High amplitude slowing with no organized background, and multifocal spikes (left and right frontal in this sample). This is a phenotype of the first year of life and is associated with West syndrome (infantile spasms).

6. Spike, generalized. Significant spikes are usually followed by a slow wave, as shown here. This example also illustrates that generalized spikes are typically maximum frontally. This is typical of the primary (idiopathic, genetic) epilepsies. If the burst lasted 3 seconds or more, it could be classified as spike-wave complexes.

7. Slow spike-wave complexes (SWC). In addition to being slower, this is also less monomorphic than the 3 Hz SWC. With other findings, this is often seen in the symptomatic/ cryptogenic epilepsies of the Lennox-Gastaut type.

8. Hypsarrhythmia. High amplitude (note the scale)slowing with no organized background, and multifocal spikes (right frontal and left occipital in this sample). This is a phenotype of the first year of life and is associated with West syndrome (infantile spasms).

9. Polyspike, generalized. Note the aftergoing slow wave. This is associated with the “primary” or Idiopathic (genetic) generalized epilepsies, most typically Juvenile Myoclonic Epilepsy.

10. Generalized paroxysmal fast activity and electrodecrement. This pattern is characteristic of the the symptomatic/ cryptogenic epilepsies of the Lennox-Gastaut type, and may be subclinical or associated with tonic or atonic seizures.