Generalized Paroxysmal Fast Activity In Idiopathic Epilepsies With Typical Absence Seizures: An Unusual Electroencephalographic Finding

Objectives: Generalized paroxysmal fast activity (GPFA) is a rare electroencephalographic (EEG) finding and generally appears in symptomatic epilepsies. In this study the presence of GPFA was investigated in adult idiopathic generalized epilepsy (IGE) patients with typical absence seizures. Patients and Methods: EEG recordings of 99 adult IGE patients with typical absence seizures followed-up in epilepsy outpatient clinic were investigated and GPFA was detected in 7 cases. Two additional cases (4 males, 5 females; mean age 27 +/- 7 years; range 19-37) were included in this study, prospectively. Clinical and EEG features of patients showing GPFA were analysed and compared with those of 92 patients without GPFA. Results: The mean follow-up period was 5 +/- 6 years (range 1-17). Generalized paroxysmal fast activity was detected in 7% of IGE patients with absence seizures. In 5 patients, generalized paroxysmal fast activity was observed during ictal period and in 4 patients during interictal period. The duration of discharges varied between 0,5 and 15 sec, with a frequency between 8-20 Hz. They appeared either isolated, or related to generalized spike and wave discharges. Unclassified absence epilepsies in patients with GPFA were more frequent in patients without GPFA, showing a statistically significance (p=0.041). Conclusions: The significance of GPFA is unknown and we speculate it represents a different form of cortical hyper-excitability in adult IGE patients with typical absence seizures.