rophysiological 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.¹Thus 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. Bickford²and Bancaud et al³have implicated the frontal lobe as the origin of generalized spike-wave patterns. Angeleri et al⁴reported focal limbic spike-activity in presumably centrencephalic epileptics. Independent deep temporal spiking was also noted by Rossi et al⁵in patients with generalized-synchronous seizure patterns. Walker and Marshall⁶felt that widespread cortical as well as deep foci could23:T451,Results of contrast material-enhanced computed tomography (CT) and T2-weighted spin-echo magnetic resonance (MR) imaging were correlated with pathologic findings in 25 patients treated surgically for refractory partial epilepsy. Of 12 lesions present, ten (83%) were detected by MR imaging and seven (58%) by CT scanning. Of nine low-grade gliomas, eight were detected by MR imaging and four by CT scanning. One posttraumatic scar and one case of temporal lobe atrophy were better demonstrated by MR imaging. A small, thrombosed arteriovenous malformation was the only lesion detected by CT scanning but not by MR imaging. No lesions were detected in 13 patients with mild gliosis and one patient with a 1.2-cm grade 1 astrocytoma. Although more sensitive than CT for detection of structural lesions in patients with refractory partial epilepsy, MR imaging resulted in a 25% false-negative diagnostic rate when a repetition time of 2,000 msec and echo time of 60 msec were used. Multi-echo imaging with at least one long echo time may be needed to increase the sensitivity of MR imaging in these patients.24:T5d5,

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