Identifying seizure clusters in patients with psychogenic nonepileptic seizures

- Clusters occur in clinical practice in patients with PNES, though a paucity of research exists on clusters in the literature.
- The present study examines seizure clustering in a sample with PNES using patient seizure diaries from a clinical trial.
- A common cluster definition from the epilepsy literature was used to identify clusters, along with statistical approaches.
- Depending on cluster definition, prevalence of clusters was 62-68% and rate of occurrence was 6-19%

The present study explored how seizure clusters may be defined for those with psychogenic nonepileptic seizures (PNES), a topic for which there is a paucity of literature. The sample was drawn from a multisite randomized clinical trial for PNES; seizure data are from participants' seizure diaries. Three possible cluster definitions were examined: 1) common clinical definition, where ≥ 3 seizures in a day is considered a cluster, along with two novel statistical definitions, where ≥ 3 seizures in a day are considered a cluster if the observed number of seizures statistically exceeds what would be expected relative to a patient's: 1) average seizure rate prior to the trial, 2) observed seizure rate for the previous seven days.Prevalence of clusters was 62-68% depending on cluster definition used, and occurrence rate of clusters was 6-19% depending on cluster definition. Based on these data, clusters seem to be common in patients with PNES, and more research is needed to identify if clusters are related to triggers and outcomes.