Purpose: This study aims to characterize the natural history of generalized motor seizures through longitudinal stratification of patient-reported clinical seizures into high, medium and low rates of generalized motor seizures (also known as generalized tonic-clonic seizures or GTCs).
Methods: From 2007 to 2018, 1.4 million seizures were recorded by 12,402 SeizureTracker.com users that met inclusion/exclusion criteria. The number of GTCs per year since the first seizure diary entry was calculated for each user and categorized as: Low (0 GTCs/year), Medium (1-2 GTCs/year), or High (>3 GTCs/year) GTC rates.
Results: Kaplan-Meier survival curves for the time until exiting the initial category were computed. There was a global difference between risk groups (p < 0.01). Further pairwise log rank tests revealed a difference between each pair of risk groups (p < 0.01). At 3 years, 40.8% of people initially presenting with high GTC rates remained in their initial category, while 77.3% of people initially presenting with low GTC rates remained in their initial category.
Conclusion: A patient with a low rate of GTCs is likely to remain at low risk for future GTCs, whereas higher GTC rate patients (at least one GTC/year) may leave their initial risk stratification. Thus, yearly re-assessment may be prudent when considering risk of further GTCs. Given the association between higher yearly rates of GTCs with increased SUDEP risk and morbidity in epilepsy, further validation of these findings is important for prognostication.
Keywords: Electronic diaries; Epilepsy; Natural history studies (prognosis); SUDEP.
Copyright © 2020 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.