Abstracts

Rationale: Generalized tonic-clonic seizures (GTCSs) in idiopathic generalized epilepsy (IGE) occur frequently during wakefulness. Secondary GTCSs (sGTCSs) in frontal lobe epilepsy (FLE) also tend to occur during wakefulness, although simple and complex partial seizures in FLE are more common during sleep. Conversely, sGTCSs in occipital lobe epilepsy (OLE) occur mainly during sleep. GTCSs in IGE occur frequently in the early morning and evening. However, whether the time of day when sGTCSs occur is associated with epilepsy classification is not clear. The relationships between epilepsy classification and the time of day as well as sleep stage were investigated in patients with GTCSs including sGTCSs. Methods: Eighty patients with epilepsy (47 men, aged 13-51 years) who had a GTCS during long-term video EEG monitoring from 2013 to 2016 were included in this study. All patients had only one GTCS during video EEG monitoring. Twelve of 19 patients with generalized epilepsy were diagnosed as IGE and the remaining 7 as symptomatic generalized epilepsy (SGE). Twenty-three of 61 patients with focal epilepsy were diagnosed with temporal lobe epilepsy (TLE), 17 with FLE, 5 with OLE, 2 with parietal lobe epilepsy (PLE), and the remaining 14 were not specified. Sleep stage at seizure onset was scored based on American Academy of Sleep Medicine criteria. The timing of seizure onset was also investigated by dividing the day into 8 periods of 3 hours. Results: All 12 patients with IGE had a GTCS during wakefulness. Four of 7 patients with SGE had a GTCS during wakefulness, whereas 3 had a GTCS during non-REM sleep. Ten of 17 patents with FLE had a sGTCS during wakefulness, whereas 7 had a GTCS during non-REM sleep. Thirteen of 23 patients with TLE had a sGTCS during wakefulness, 9 had a GTCS during non-REM sleep, and one had a GTCS during REM sleep. All 5 patients with OLE had a sGTCS during wakefulness. Both patients with PLE had a sGTCS during non-REM sleep. Investigation of timing of GTCSs in the awake state found sGTCSs in FLE tended to occur in the daytime, whereas GTCSs in IGE tended to occur in the early morning and evening. Moreover, sGTCSs in TLE tended to occur after evening, which is less common in FLE. Conclusions: Information about the time of day as well as sleep stage at seizure onset is important for epilepsy classification of patients with GTCSs, especially those with IGE, FLE, and TLE. Funding:  None.