Use of an online epilepsy diary to characterize repetitive seizures

Abstract Significance Little is known about patterns of seizures that occur multiple times a day, sometimes called clusters or serial seizures. Objective The online diary, My Epilepsy Diary (MED), provided self-reported data from community-based patients to describe the characteristics of clusters. Methods We used MED data to define a population of 5098 community outpatients, including 1177 who specified time of multiple seizures in a 24-hour period. Outcomes included cluster prevalence and frequency, distribution of interseizure time intervals, as well as the types of triggers commonly reported. Results One-fourth of days with any seizures included clusters for these patients. Most days with clusters included 2 seizures, with > 5 events occurring in only 10% of days. One-third of seizures occurred within 3 h of the initial event and two-thirds within 6 h. When more than 2 seizures occurred, the time to the next seizure decreased from an average of over 2 h (to the 3rd event) to a quarter-hour (from the 4th to the 5th event). Conclusion My Epilepsy Diary data have provided the first overview of cluster seizures in a large community-based population. Treatments with less than 3-hour duration of action would be bioavailable at the time of only one-third of subsequent seizures. Although limited by the self-reported and observational nature of the diary data, some general patterns emerge and can help to focus questions for future studies.