Abstracts

Rationale: Generalized paroxysmal fast activity (GPFA) consists of burst of generalized rhythmic discharges; 100-200 μV; 8-26 Hz; lasting 2-50 seconds; with frontal predominance; appearing during NREM sleep. We analyzed GPFA in children with intractable localization-related epilepsies, who underwent surgical resection to understand a significance of GPFA correlating with the epileptogenic zone. Methods: We collected patients with GPFA among the patients who underwent scalp video EEG, MRI, MEG, intracranial video EEG and surgical resection. We analyzed characteristics of GPFA, correlating with clinical features, findings of EEG and surgical resection. Results: We found 14 (13.5%) patients (7 females) with GPFA among 103 patients who underwent epilepsy surgery at the Hospital for Sick Children in Toronto (2004-2012). Age of seizure onset ranged between 2 months to 10 years old (mean, 4.1 years). Five patients presented with partial seizures, and two patients had epileptic spasms. Seven patients had multiple type of seizures. Epilepsy surgery was performed between 5 to 18 years of age (mean, 12 years). GPFA appeared bilaterally in NREM sleep in all patients. The amplitude ranged 90-300μV. Seven patients presented the predominantly higher amplitude of GPFA in one hemisphere which was surgical site. The frequencies of spikes ranged 8-16Hz. Rhythmic spike patterns were associated with spike and slow wave complex in 12 patients. The other 2 patients did not have spike and slow waves during and after GPFA. The duration ranged 1-6 seconds. GPFA lasting 5 seconds appeared at the seizure onset in one patient. GPFA occurred frequently (more than 60% of NREM sleep) in 7 patients, intermittently (30%-60%) in 2 and occasionally (< 30%) in 5. Conclusions: GPFA can be seen in the intractable localization-related epilepsy. The amplitude predominance of GPFA correlated with the epileptogenic hemisphere.