THE origin and neurophysiological mechanisms of generalized-synchronous spikewave discharges continue to be subjects of controversy. It was presumed for many years that these discharges arise from the intralaminar thalamic nuclei and thence fan out into the diffuse thalamo-cortical projections.1 Thus the concept of "centrencephalic" seizures arose to explain petit mal and "pure" grand mal.
The postulated thalamic origin of generalized-synchronous seizure patterns has been challenged by experimental as well as clinical investigations. Depth electroencephalographic studies in epileptic patients with generalized spike-wave complexes often reveal focal components. Bickford2 and Bancaud et al3 have implicated the frontal lobe as the origin of generalized spike-wave patterns. Angeleri et al4 reported focal limbic spike-activity in presumably centrencephalic epileptics. Independent deep temporal spiking was also noted by Rossi et al5 in patients with generalized-synchronous seizure patterns. Walker and Marshall6 felt that widespread cortical as well as deep foci could