The relationship between bilateral spike and wave complexes and focal discharges in patients with partial epilepsy.

The goal of this study was to investigate in patients with partial epilepsy the relationship between bilateral spike and wave (BSW) complexes of a generalized epilepsy and the focal spikes of partial epilepsy. For the study 300 patients were collected, all with focal epilepsy on their last hospital visit: 150 were well controlled (C) and 150 were uncontrolled (U), and the number of EEGs was 674 in the C and 804 in the U groups. BSW were seen at some time in 25% of all patients, more often in the U than C patients, especially the irregular 3/sec form. The bilateral complexes at times appeared at the onset of the epilepsy, usually at the same time with focal discharges, mainly from temporal or frontal areas. The U patients showed these complexes at a younger age than the C group and continued to be seen often into the 30s, occasionally into the 60s age group. The other presentation of the BSW was years after the onset of the focal discharges, usually temporal or frontal in location and more often seen in the U than C group. The U group showed spikes, many in number as active foci, more often than the C group. The discussion deals with the possibility that these bilateral spike and wave complexes may represent a reflection of a lowered threshold to a seizure.