Conference Coverage

Onset of pediatric status epilepticus may have a circadian pattern



The onset of pediatric refractory status epilepticus follows a circadian pattern, according to research presented at the annual meeting of the American Epilepsy Society. The number of episodes is greatest between 10 a.m. and 11 a.m. and smallest between 10 p.m. and 11 p.m.

“Our findings may inform the increase in preventive monitoring, such as video monitoring or seizure-tracking devices for patients,” said Justice Clark, MPH, a program coordinator at Boston Children’s Hospital. “They may also inform chronotherapeutic strategies.”

Research suggests that various types of seizures cluster at different times of the day. Data about the circadian distribution of status epilepticus, however, are limited.

Ms. Clark and colleagues conducted a prospective observational study at 25 hospitals in the United States and Canada from June 2011 to January 2018. Eligible participants were between ages 1 month and 21 years, had focal or generalized convulsive status epilepticus, and had failed to respond to one benzodiazepine and one nonbenzodiazepine antiseizure medication. For patients with more than one episode of refractory status epilepticus during the study, the researchers included only the first episode.

The investigators examined whether the temporal distribution of pediatric refractory status epilepticus onset followed a circadian pattern using a cosinor analysis with a 12-hour cycle. They used the midline-estimating statistic of rhythm (MESOR) technique to estimate the mean number of refractory status epilepticus episodes per hour if onset was evenly distributed. The amplitude in this analysis was the difference in number of episodes per hour between the MESOR and the peak or the MESOR and the trough.

Ms. Clark and her colleagues included 300 patients in their analysis, each of whom had one episode. Approximately 45% of participants were female. The population’s median age was 4.2 years, and the median duration of status epilepticus was 120 minutes.

The MESOR was 12.5 episodes per hour, and the amplitude was 2.4 episodes per hour, indicating that the distribution was not even over 24 hours. The peak number of onsets was between 10 a.m. and 11 a.m., and the trough was between 10 p.m. and 11 p.m.

A secondary analysis examined the circadian distribution of time to treatment with rescue medications. The distribution of time to treatment with the first benzodiazepine did not differ significantly from a uniform distribution. The time to treatment with the first nonbenzodiazepine antiseizure medication, however, was not uniformly distributed. The longest time to treatment occurred between 3 a.m. and 4 a.m., and the shortest time was between 3 p.m. and 4 p.m. “Although fewer refractory status epilepticus episodes occurred at night, the time to antiseizure medication administration was the longest [during that period]. Thus, nighttime refractory status epilepticus episodes may be at higher risk for delayed treatment,” said Ms. Clark. A limitation of this analysis is that it was influenced by outliers, she added.

The Pediatric Epilepsy Research Foundation and the Epilepsy Research Fund supported the study.

SOURCE: Clark J et al. AES 2018. Abstract 3.426.

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