The last few years, various features have been proposed to assist in the detection and Classification of Seizure activity. An important application is in continuous monitoring of  patients in the ICU, including newborns. A recent paper discusses Nearest Neigbhour Phase Synchronization, but various other features are relevant, as well.

M.J.A.M. van Putten, Nearest Neighbour Phase Synchronization to detect Seizure Activity from Scalp EEG recordings, J. Clinical Neurophysiology 20(5):320-325 (2003)

Two students from Delft University, Frank Visser and Taco Kind, made a most valuable contribution to this topic, as well. Their final report (June 2003, in Dutch) can be found here .

Patients suffering from a non-convulsive status epilepticus may show recurrent bursts in their EEG, indicating low-dimensional behavior. These patterns were recently studied in more detail in MJAM van Putten and MHPM van Putten, Discovery of recurrent multiple brain states  in non-convulsive status epilepticus, Clin Neurophysiology, 118, 2798-2804, 2007.