Fast oscillations as useful biomarkers of the degree of epileptogenicity in each generalized epilepsy syndrome

To evaluate scalp fast oscillations (FOs) superimposed on spike-and-wave complexes (SWCs) as biomarkers of epileptogenicity in generalized epilepsy syndromes.

We analyzed scalp electroencephalography of patients with absence epilepsy (AE), juvenile myoclonic epilepsy (JME), benign adult familial myoclonus epilepsy (BAFME), and Lennox-Gastaut syndrome (LGS). FOs were identified based on predefined time-frequency/time-domain criteria. We evaluated (1) FO-positive rate (FO-PR) and occurrence rate (FO-OR), (2) factors related to seizure frequency, and (3) within-patient FO-OR variability.

We analyzed 48 patients (BAFME 13, AE 13, JME 13, LGS 9). (1) LGS showed the highest FO-PR (100 %) among the 4 groups (BAFME, 23.1 %; AE, 46.2 %; JME, 38.5 %). FO-OR was also highest in LGS (22.6 ± 11.0 %) (BAFME, 4.7 ± 8.2 %; AE, 5.1 ± 8.7 %; JME, 5.3 ± 8.4 %). (2) Weekly-or-more seizures were associated with earlier onset, LGS diagnosis, more antiseizure medications, slower SWC frequency, more SWCs, FO positivity, and higher FO-OR; multivariate analysis identified FO positivity and LGS diagnosis as independent factors. (3) FO-OR tended to increase with higher seizure frequency.

Scalp FOs could be biomarkers for syndrome classification and for seizure control across patients.

Scalp-recorded FOs could be biomarkers of disease severity and epileptogenicity of 4 generalized epilepsy syndromes.