How accurately do adult patients report their absence seizures?

We depend upon self-reporting to determine seizure frequency for epilepsy management decisions, but people often misreport their seizures. Here, we determined misreporting rates in adults with absence seizures, undergoing inpatient video-EEG telemetry (VET) or outpatient ambulatory electroencephalography (aEEG). Under-reporting rates were based on VET data, where behavior could be assessed, whilst over-reporting was assessed using both VET and aEEG. Forty-two patients (31 female and 11 males, median age 28.5 years) and 759 reported absence seizures were included in this study. Overall, only 24% of the 759 reported seizures had an associated EEG correlate, indicating a high over-reporting rate, which occurred in 57% of patients. Age, sex, time of epilepsy, VET versus aEEG, epilepsy syndrome or medication were not significant predictors of over-reporting. In the VET group in which we could assess both over- and under-reporting (22 patients), only 2 patients correctly reported their seizures, and patients were predominantly over-reporters or under reporters, not both. Only 26% of 423 absence seizures were reported. Use of zonisamide or valproate was associated with under-reporting, possibly through an impact on attention. These findings indicate that self-reported AS are a poor measure to use for treatment decisions due to both over- and under-reporting.