Computerized analysis of EEG background activity in epileptic patients.

Background activity was studied in 128 idiopathic epilepsy patients and 30 normal controls using EEG topography and t-statistic significance probability mapping (t-SPM). In epileptic patients, EEG background activity showed a marked increase in delta, theta, alpha 1, and beta 1, and a decrease in alpha 2 activity as compared with controls. Untreated epileptic patients had a significant increase in delta, theta, and alpha 1 as compared with controls. For epileptic patients treated with antiepileptic drugs (AEDs), the most marked slowing was observed in the polytherapy group, followed by the monotherapy group and then the untreated group. Among seizure types, patients with partial seizures (PS) tended to exhibit more slowing than patients with only generalized tonic-clonic seizures (GTC). Moreover, PS had a right-left asymmetry in alpha 2 and beta 1 activities. In a comparison of AEDs, patients receiving carbamazepine (CBZ) and phenobarbital (PB) showed no significant difference as compared with the untreated group. In contrast, patients receiving valproate (VPA) showed a decrease in slow and fast activities. EEG changes associated with each AED were different in GTC and PS. Patients receiving VPA for GTC showed a decrease in theta and beta 1 activities, but those with PS showed a decrease only in delta activity.