The clinical correlates of 154 children with epilepsy and generalized spike-and-wave (SW) EEG patterns were analyzed at the pediatric neurology units, HU de Getafe and Hospital 12 de Octubre, Madrid, Spain. Mean age at seizure onset was 6 years (range, 0-14 years). Eighteen percent had learning disorders, and 14% had a history of febrile seizures. Ten percent of first-degree relatives had epilepsy. Absence seizures were the most frequent type at onset (36%); tonic-clonic seizures occurred in 27%, and complex partial seizures in 14%. More than 40% had several types of seizures at time of evaluation: 48% had at least one tonic-clonic, 46% absence, 20% complex partial. Epilepsy syndrome diagnoses included idiopathic generalized epilepsy (49%), and partial epilepsies (24%). The typical SW EEG pattern was usually associated with a single type of seizure, mainly idiopathic absence, normal neurologic exam and CT scan, no learning problems, and favorable outcome with monotherapy, sustained after drug withdrawal. Slow SW correlated with more than one type of seizure (atonic, myoclonic, tonic, and partial), West syndrome, psychomotor retardation, abnormal CT, polytherapy and poor seizure control. Fast SW occurred with partial and secondary generalized seizures, normal CT, and seizure recurrence after drug withdrawal. 
COMMENT. The typical SW EEG pattern associated with absence seizures has a much more benign outcome than the slow SW, usually associated with West and Lennox Gastaut syndromes. In contrast, the clinical course of children with the fast SW EEG is more difficult to predict, being associated with single isolated seizures and a tendency to seizure recurrence. Typical SW is 10 times more likely to correlate with seizure remission and successful drug withdrawal than the slow SW pattern.