Authors :
Presenting Author: Andreas Schulze-Bonhage, MD – University Hospital Freiburg, Germany
Armin Brandt, Biologist – Epilepsy Center, University Hospital Freiburg, Germany; Nicolas Zabler, Engineer – Epilepsy Center, University Hospital Freiburg, Germany; Matthias Dümpelmann, Engineer – Epilepsy Center, University Hospital Freiburg, Germany; Victoria San Antonio-Arce, MD – Epilepsy Center, University Hospital Freiburg, Germany
Rationale:
Cycles of seizure occurrence have become a topic in the context of risk assessment, seizure forecasting and chronotherapy. The validity of patient-based seizure documentation has been questioned as patients may not be aware of seizures or may have complete or partial retrograde amnesia of seizure manifestations. We here analyzed if underreporting of seizures may affect the timing and circadian distribution of seizures in comparison to objective seizure documentation using video-EEG recordings.
Methods:
Data from 1214 patients (mean age: 32.8, range: 10-83, 49.6% female) in whom seizures were documented during in-hospital long-term video-EEG monitoring at the Freiburg Epilepsy center were analyzed. 45.7% had a temporal and 14.8% had a frontal lobe origin; 11.5% of patients had idiopathic generalized epilepsy. The circadian cyclical timing of patient alarms was compared to objective timings of seizure onsets. Patient-triggered button presses were considered associated with objective seizure timing when markers of button presses were within a time window of 180s before to 420s after video-EEG-based markers of seizure onset. A time window of three minutes prior to the onset of EEG changes and objective seizure manifestations was allowed to correctly classify ictal manifestations based on subjective experiences as seizure-related. The circadian occurrence of patient-reported and of objectively documented seizures with a maximum of five seizures per patient taken into consideration was compared using Watson’s two-sample test of homogeneity.
Results:
33.3% of seizures of temporal origin were reported by patients, 19.9% of frontal lobe seizures and 13.2% of primarily generalized seizures. Differences in circular means of reported and documented seizures were largest in temporal lobe epilepsy (3:12 p.m. in reported vs. 8:34 a.m. in documented seizures, Fig. 1), in the range of several hours in frontal lobe epilepsy (0.56 a.m. for reported vs 3:45 a.m. for documented seizures). The temporal distributions of reported seizures were significantly different from those of documented seizures in all three subgroups (Watson's test for homogeneity on two samples of circular data, temporal lobe epilepsy: p< 0.001; frontal lobe epilepsy: p< 0.01; idiopathic generalized epilepsy: p< 0.05).