Abstracts

Rationale: Generalized paroxysmal fast activity(GPFA) consists of burst of generalized rhythmic discharges; 100-200μV; 1-9sec; 8-26Hz; with frontal predominance; appearing during NREM sleep. GPFA was originally described as an electrographic feature of Lennox-Gastaut Syndrome. GPFA also can be found in localization-related epilepsy with secondary generalization or secondary bilateral synchrony. But there are no reports described about patients with GPFA who underwent epilepsy surgery. Characteristics of GPFA and its correlation with epileptogenic zone remain unclear. We analyzed GPFA on scalp video EEG(VEEG) to characterize GPFA in children with intractable localization-related epilepsy. We hypothesized that asymmetry of GPFA would be present in those children secondary to resectable epileptogenic zone. Methods: We retrospectively identified children with GPFA among 103 children who underwent epilepsy surgery from 2004 to 2012. All children underwent prolonged scalp VEEG, MRI and MEG prior to intracranial VEEG(IVEEG) and surgical resection. We collected first 50 epochs of GPFA in each child on scalp VEEG during NREM sleep. We analyzed amplitude, duration and frequency of GPFA over the bilateral frontal region between surgical resection and non-resection side(Figure 1). Results: We identified 14 children with GPFA on scalp VEEG. Nine of 14 children had partial seizures, including 2 with secondary generalization. Three children had generalized tonic-clonic seizures. Seven children had epileptic spasms. The amplitude ranged from145 to 589μV(mean 293μV). The duration ranged from 1.18 to 2.31sec(mean 1.6sec). The frequency ranged from 9.3 to 14.7Hz(mean 11.1Hz). The amplitude(307±156µV) and duration(1.62±0.8sec) of GPFA in all children over resection side were significantly higher than those(279±141µV, 1.58±0.8sec) of non-resection side(p<0.001). Frequency of GPFA in all children was no significant difference between resection(11±2.1Hz) and non-resection side(11±2.2Hz). Nine children had significantly longer duration of GPFA over resection side(p<0.05). Eight children had significantly higher amplitude over resection side(p<0.05). Four children had significantly higher frequency over resection side(p<0.05). The seizure onset zone were localized on the multiple lobes in 12(86%) children, consisting of three lobes in 5 and two lobes in 7. Following IVEEG, 13 of 14 children underwent resective surgery including multilobar resection for 11 children. Nine(69%) children became seizure free after surgical resection. Conclusions: GPFA can exist in localization-related epilepsy. The amplitude and duration of GPFA may contribute to excitability in epileptogenic cortex(Figure 2). The bilateral identical rhythm of GPFA may show secondary bilateral synchrony due to thalamo-cortical network. Although patients with GPFA present multiple seizure onset zones, the precise localization of the extensive epileptogenic zones using IVEEG could achieve the successful surgical resection for good seizure outcome.