Simultaneous EEG-VTR and transverse topographical analyses of absence seizures in children. Some prognostic implications.

The clinical symptoms and electroencephalographic (EEG) features of typical absence seizures, including transverse topographical analysis (TTA), were studied retrospectively using a simultaneous EEG-VTR system in 36 children aged between 3 and 17 years. Complex absences were more common than simple, and oral automatisms were the most frequent complex symptoms. Occurrence of complex symptoms was directly proportional to the length of seizures. There was no association between lateral TTA type and simple absences. Prognosis was favorable in patients with long seizure duration (P < 0.01), bilaterally synchronous monomorphic spike-waves throughout the seizure discharges (BSMTSD) (P < 0.005) and lateral TTA type (P < 0.05). Two different mechanisms of origin for BSMTSD/non-BSMTSD and lateral/non-lateral TTA types are probably responsible for the difference in prognosis. Favorable prognosis in patients with long seizures is discussed in relation to the duration of the illness. EEGs with BSMTSD and lateral TTA type may indicate a favorable prognosis in children with absence seizures.