Generalized absence seizures with 10–15 Hz fast discharges

Abstract

Objective: To report clinical and EEG features in 5 adults with unusual., fast rhythmic discharges accompanying absence seizures.Design and methods: The 5 patients presented with uncontrolled seizures. All had EEG-video monitoring with recorded seizures. Video seizures were reviewed and ictal as well as interictal epileptiform activity was analyzed. The patients were followed up after appropriate therapy for a minimum of 6 months.Results: There were 3 women and two men, with a mean age of 37 years (range: 23–59). Two patients had onset of absence seizures in childhood, one in adolescence and two after age 20. All patients also had generalized tonic-clonic seizures. Ictal EEG recordings showed generalized spike and wave (SW) discharges of variable dominant frequencies (2.5–6 Hz) and intermingled 10–15 Hz generalized rhythmic discharges which also occurred in isolation or as the dominant activity. Interictal recordings showed similar but shorter 2.5–6 Hz generalized SW discharges. The background activity was normal in 3 patients and mildly slow in two who had very frequent absence seizures during the recording period. Four patients became seizure free and one had 75% improvement on appropriate antiabsence therapy.Conclusions: The fast 10–15 Hz rhythmic discharges that we report appear to occur mostly in adult patients with absence, as well as, generalized tonic-clonic seizures. They can occur in isolation or be embedded in more typical SW discharges accompanying typical absence seizures. Their presence does not imply a poor prognosis for seizure control.