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. 2021 Aug 4:12:720328.
doi: 10.3389/fneur.2021.720328. eCollection 2021.

Epileptic Seizure Cycles: Six Common Clinical Misconceptions

Philippa J Karoly  1   2 , Dean R Freestone  1 , Dominique Eden  1 , Rachel E Stirling  1   2 , Lyra Li  2 , Pedro F Vianna  3   4 , Matias I Maturana  1   5 , Wendyl J D'Souza  5 , Mark J Cook  2   5 , Mark P Richardson  3 , Benjamin H Brinkmann  6 , Ewan S Nurse  1   5
Affiliations

Epileptic Seizure Cycles: Six Common Clinical Misconceptions

Philippa J Karoly et al. Front Neurol. .
No abstract available

Keywords: EEG; epilepsy; multiday cycles; seizure cycles; wearables.

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Conflict of interest statement

PK, DE, RS, EN, MM, DF, and MC have employment or financial interest in Seer Medical Pty. Ltd., which provides diagnostic EEG services. WD'S has employment or financial interest in KeyLead Health. WD'S and MC have employment or financial interest in Epi-Minder Pty. Ltd. MR has a research collaboration with UNEEG medical and has been a member of their advisory board. BB has a financial interest in Cadence Neurosciences Inc., and has received nonfinancial research support (devices for a study) from Medtronic Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Case study of electrographic seizure detection from sub-scalp EEG (red) and seizure diary self-reported events (green) over >6 months in an individual patient. (A): counts of detected epileptiform events over time, with seizures shown as dots. (B) Synchronisation index measured from event times at different fixed cycle periods showed a similar peak around 28-days for both EEG and self-reported seizures (C) A polar plot demonstrating that both diary and EEG seizures show similar phase distributions with respect to the underlying 28-day cycle.
Figure 2
Figure 2
Case study of 7-day weekly seizure cycle and 8.5-day heart rate cycle showing that seizures were not modulated by weekly behaviour. (A) 8-week seizure diary showing days that seizures occurred, suggesting a weekly seizure cycle. (B) 8.5-day heart rate cycle of the same period as (a), with seizures shown in green. Seizures tend to occur on the rising phase of the cycle, with a few exceptions. (C,D) Polar plots demonstrating the location of seizures with respect to the 7-day seizure (red) and 8.5-day heart rate cycle (green) after two months and 35 seizures. Seizures were more strongly locked to the 7-day week. (E,F) Polar plots demonstrating seizure timing on the seizure and heart rate cycle after 15 months and 245 seizures. Seizures were no longer locked to the weekly cycle but remained strongly locked to the 8.5-day heart rate cycle. SI, Synchronisation index value with significance according to Omnibus test (***p <= 0.001).
Figure 3
Figure 3
Case study of a catamenial seizure cycle showing that seizures are only transiently aligned to the menstrual phase. (A) 4-month seizure diary showing days that seizures occurred, and times of menstruation, suggesting a catamenial seizure cycle. (B,C) Polar plots demonstrating the location of seizures with respect to the menstrual cycle after four months and 26 seizures (B) and after 19 months and 133 seizures (C).
Figure 4
Figure 4
Case study of an individual with juvenile absence epilepsy with 5 and 13-day seizure cycles. (A) Self-reported seizure counts (bin-width of 5 days). (B) Estimated seizure likelihood (grey—raw likelihood estimate, colour—smoothed likelihood). Markers indicate self-reported seizure occurrences. Note that the majority (79%) of seizures occurred when the seizure likelihood was high.
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References

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