Epileptic spasms in clusters and associated syndromes other than West syndrome: A study of 48 patients.

OBJECTIVE: To study the different epilepsy syndromes that included epileptic spasms (ES) in clusters without hypsarrhythmia (WoH).

METHODS: Between 2/1990 and 7/2013, we registered 48 patients with the electroclinical diagnostic criteria of ES in clusters WoH.

RESULTS: We recognized two subgroups. In the first subgroup of 30 patients, ES started at a mean age of 10.6 months (range, 2-40 months). Ictal EEG recordings showed diffuse high-amplitude slow waves in 15 patients, diffuse slow waves followed by voltage attenuation in six patients, diffuse fast rhythms in five, diffuse slow waves with superimposed fast rhythms in three, and diffuse sharp waves in one. In the second subgroup of 18 patients, nine had electroclinical features of Lennox-Gastaut syndrome, four had epilepsy with myoclonic and atonic seizures, two had Dravet syndrome, one 6-year-old boy had a non-convulsive status epilepticus characterized by atypical absences associated with ES, one had epilepsy with migrating seizures of infancy, and one patient had clinical features of subacute sclerosing panencephalitis with ES. ES started at a mean age of 6.3 years (range, 0.5-13 years). The ictal EEG recording during the ES showed diffuse fast rhythms in 10 cases, diffuse slow waves with superimposed fast rhythms in four, and diffuse slow waves in four.

CONCLUSION: Our study shows two subgroups of children with ESWoH. The first subgroup had a well-defined electroclinical syndrome predominantly in infancy, and in the second subgroup ES was one more seizure type associated with an epileptic encephalopathy other than West syndrome predominantly occurring in childhood.