Multiday Cycles of Heart Rate Modulate Seizure Likelihood at Daily, Weekly and Monthly Timescales: An Observational Cohort Study

Seizure Forecasting Using a Novel Sub-Scalp Ultra-Long Term EEG Monitoring System

“…In the current work, there was clear rhythmicity in the detected events ( Figure 3A ), which is concordant with previous work with invasive EEG showing the prevalence of circadian and multiday cycles in interictal EA ( 17 , 18 ) and seizures ( 20 , 29 , 31 ). Using a similar approach to previous work ( 20 , 40 ), cycles were detected at circadian and multiday periodicities for one individual ( Figure 3B ), with 18-day and 29-day cycles in the detected events showing the strongest relationships with seizure timing ( Figures 3C,D ). Interestingly, multiday cyclesin this subject were stronger than the circadian rhythm.…”

“…Lack of sleep and deviations from normal sleep patterns are known risk factors for seizures. Conversely, the treatment of seizures and seizures themselves can disrupt normal sleep patterns ( 40 , 41 ). Sub-scalp devices provide an opportunity to investigate the complex relationship between sleep and seizures and can aid in patient management and seizure forecasting ( 39 ).…”

Epileptic Seizure Cycles: Six Common Clinical Misconceptions

“…On the other hand, advances in chronic EEG recording have shown that seizure cycles are more reliably estimated by continuously monitoring biomarkers of excitability ( 5 ). For instance average rates of interictal epileptic activity ( 4 ), the variance and autocorrelation of EEG ( 15 ), and even average heart rate ( 21 ) all show multiday cycles that are more robustly predictive of seizure likelihood than looking at past seizure times. Additionally, a recent comparison of seizure diaries and epileptic activity captured from chronic sub-scalp recording systems ( 22 ) showed discrepancies between the cyclic distributions of self-reported and electrographic events, even when diaries were relatively accurate ( 23 ).…”

“…It has been hypothesised that endogenous weekly cycles do influence mammalian physiology, with evidence of such cycles affecting the cardio-respiratory, immune, and endocrine systems ( 34 ). A recent study found people with epilepsy showed weekly fluctuations in resting heart rate that were related to their seizure occurrence ( 21 ). Similar to epileptic activity, heart rate cycles were found at patient-specific periods of between 5 and 9 days and not necessarily linked to weekdays.…”

“…However, such historic diagnoses are highly speculative and cannot be relied upon. Contemporary diary studies have shown multiday seizure cycles can be measured from self-reported event times in people with GGEs ( 7 , 9 ), and have corresponding cycles of heart rate activity ( 21 ).…”