Multi-day Rhythms Modulate Seizure Risk in Epilepsy

Baud MO, Kleen JK, Mirro EA, et al. Nature Communications 9(2018): 88.

Background

• Seizures often seem to be random occurrences, but some evidence suggests that seizure events may follow daily or monthly patterns.
• Knowing this cyclic pattern of abnormal electrical activity may help people living with seizures and physicians better control (and potentially prevent) seizures and their effects.

Methods

• The study used seizure data from 37 subjects that had responsive neurostimulation (RNS).
  • RNS is a device or stimulator that monitors brain waves and responds to activity that is different from usual or that looks like a seizure.
  • Learn more about RNS here.
• The people were followed for close to 10 years to get an accurate impression of seizure characteristics.

Results

• The authors found that seizures occur in cycles or "rhythms" that repeat every several days to weeks, called "multidien rhythms" (i.e., cycles lasting days, weeks, or months).
• This study showed that for most people with epilepsy, multidien rhythms predict seizure risk (i.e., seizures occurred during a particular phase of the rhythm).
• For each person, their individual rhythm remained consistent over many years.

Implications for People Living with Epilepsy

• Investigating biomarkers of epilepsy is a subject of active exploration.
• Many people living with epilepsy report there is a rhythm to their seizures; this study proposes a way to measure this phenomenon.
• The multidien rhythms described in this study will likely be crucial for predicting seizures in the future, and the authors of this study are already working on this goal.
• These rhythms also suggest there could be some underlying biological cause that could influence seizure risk, a potential mechanism being hormones.
  • One could envision future studies aimed at identifying these biological influences, and studying them in greater detail.
  • Targeting these influences could be an additional method to decrease seizures.
• This current study was done in people with refractory focal epilepsy. Whether a similar rhythmic pattern can be found in other types of epilepsies needs to be further explored.