Cyclic Patterns Found in Epileptic Seizures

cyclic seizures methodology

Epilepsy News From:

Wednesday, February 6, 2019

A new study finds evidence of cyclic seizure patterns in most epilepsies. This information can help doctors and people living with epilepsy predict and preempt seizures.

Introduction

  • Many have suspected that seizures may have cyclic patterns.
  • If seizures can have rhythms, it would be possible to predict when seizures will occur. For many people living with epilepsy, predictability could mean more control over their lifestyles and a drastic improvement in life quality.

Background

  • Past studies have reported correlations between hormonal cycles and circadian (24-hour) rhythms with seizure occurrence, but there is limited evidence for seizure cycles.
  • We still don’t know how rhythmic seizures are and if there are any common brain frequencies for seizures to occur.
  • To better understand seizure cycles in people living with epilepsy, researchers need to look over large datasets of seizure occurrence collected over a long period of time in many people.
  • In the past, such datasets were did not exist. The datasets that did exist were collected from clinical settings and were only 24 hours long, leaving the presence of long (>3 weeks) seizure cycles poorly studied.

Methods

  • In recent years, several comprehensive datasets of seizure occurrence have become available. A new study by Philippa Karoly and colleagues examined seizure cycles by analyzing two of these large datasets: SeizureTracker & NeuroVista.
  • The figure at the top of this page compares the two datasets. They have opposite amounts of data related to accuracy and sample size. Together, the datasets form a strong basis for arriving at some general findings.

Findings

  • Almost all people exhibited seizure cycles, with at least 80% showing 24-hour circadian modulation.
  • Up to 21% of people had a clear weekly (7-day) rhythm.
  • Up to 22% people had long seizure cycles that lasted more than 3 weeks.
  • Contrary to the general belief that seizure cycles are caused by hormonal cycles, the study finds no difference between men and women.
    • One way to understand this result is that gender differences disappear over a big sample size and long-term tracking.
    • However, it’s equally possible that the observation could arise from sample biases.
    • Hence, future studies are needed to verify the validity of this finding.

What does this mean?

  • These results can revolutionize how we understand and treat seizures. For the first time, it’s shown that seizure cycles exist in the majority of people living with epilepsy, regardless of sex and the type of epilepsy. We can now understand seizure occurrence as a rhythmic event with different regularities among people.
  • In the near term, we can perhaps better control seizures by varying the drug dose according to each person’s cyclic seizure pattern. This form of therapy is known as “chronotherapy.”
  • In people with circadian cycles, how quickly a drug becomes less effective in a person’s system during the day could make circadian seizure cycles. This means drugs with consistent blood concentration could suppress short-term seizure cycles more effectively.
  • As a drug’s effectiveness is less likely to affect longer seizure cycles, chronotherapy could have better results with long-term seizure management. Surprisingly, this promising treatment strategy has never been explored. After all, consistent long-term seizure record is still lacking in most people.
  • To facilitate seizure tracking, Philippa Karoly and colleagues developed a smartphone app: the “Beagle Health Tracker.” The app also allows logging events by pressing a Bluetooth button. The hope is to establish an individualized seizure rhythm for each person to help neurologists explore treatment options. (Editor’s note: the Epilepsy Foundation My Seizure Diary, available with iPhone and Android companion apps, also lets users create a seizure log.)
  • In the long run, understanding the cellular and circuit mechanisms underlying seizure rhythms could uncover new treatments. Human bodies have many cyclic activities, such as cellular metabolism, body temperature, and sleep. Many human diseases are affected by these cycles, and now we know epilepsy is too.
  • Coming next is for researchers to discover how rhythms in seizures resonate with the rhythms of our bodies.

References

  1. Fernández IS, Loddenkemper T. Chronotherapeutic implications of cyclic seizure patterns. Nature Reviews Neurology 14 (2018):696-697. https://www.nature.com/articles/s41582-018-0094-8
  2. Karoly PJ, Goldenholz DM, Freestone DR, Moss RE, Grayden DB, Theodore WH, et al. Circadian and circaseptan rhythms in human epilepsy: a retrospective cohort study. The Lancet Neurology 17 (2018) 11: 977-985. https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(18)30274-6/fulltext#relatedClinic
  3. Circadian and circaseptan rhythms in human epilepsy. EpilepsyU. Online: September 13, 2018. http://epilepsyu.com/circadian-and-circaseptan-rhythms-in-human-epilepsy
Authored by: Huayi Wei, Doctoral candidate on 2/2019
Reviewed by: Sloka Iyengar PhD on 2/2019

Our Mission

The mission of the Epilepsy Foundation is to lead the fight to overcome the challenges of living with epilepsy and to accelerate therapies to stop seizures, find cures, and save lives.

 
24/7 helpline