Circadian rhythm and sleep in focal epilepsy

Although a relationship between sleep, circadian rhythm and the occurrence of epileptic seizures was first postulated over a hundred years ago, few studies, mainly with a small number of seizures were published. In this study we analyzed all partial seizures determined by continuous EEG-monitoring to reevaluate previous results and to provide a first step towards creating chronotypes in epilepsy. Data were collected at the epilepsy monitoring unit of the Department of Neurology, LMU University Hospital in Munich from 715 patients undergoing pre-surgical long-term Video-EEG-monitoring. Only seizures with a single focal seizure onset zone were considered and were divided into five groups: frontal, temporal, parietal, occipital and central region. A total of 3950 seizures were included in the final analysis (temporal: 2055; frontal: 1512; central: 181; parietal: 90; occipital: 112). Cosinor analysis revealed a periodicity in the occurrence of seizures regarding the temporal (p = 0.019), occipital (p = 0.045) und frontal lobe (p = 0.034) whereas parietal and central region seizures did not show a 24 h periodicity. Temporal lobe seizures showed a peak at 10 am, whereas frontal lobe seizures peaked at 4 am and occipital lobe seizures at 4 pm. Most seizures occurred in the awake state (in total 64.56 %) regardless of the seizure onset zone. By knowing the peaks of seizure occurrence chronotypes can be identified and antiseizure medication can be adjusted accordingly. This might help to enhance seizure control and reduce seizure associated risk.