The Incidence of First Seizures, Epilepsy and Seizure Mimics in a Geographically Defined Area

Neurology. 2020 Jun 9;10.1212/WNL.0000000000009980. doi: 10.1212/WNL.0000000000009980. Online ahead of print.


Objective: To determine the incidence of first seizures, epilepsy and seizure mimics in a geographically defined area using the updated 2014 International League Against Epilepsy (ILAE) definition which allows an epilepsy diagnosis following a single seizure where risk of further seizures over the next 10 years is approximately 60% or more. This replaced the 1993 definition where epilepsy was diagnosed when a person had two or more seizures separated by 24 hours.

Methods: Using multiple overlapping methods of case ascertainment followed by individual case classification by an epileptologist we identified all first seizures, new diagnosis of epilepsy, and seizure mimics occurring in a defined geographical area (population 542,868) 01/01/2017-12/31/2017. Incidence was age-standardised to the Standard European Population. We compared incidence rates when using the 2014 and 1993 ILAE definitions.

Results: When applying the 2014 ILAE definition of epilepsy the incidence of new diagnosis of epilepsy was 62 per 100,000 (age-standardised 74), compared to 41 per 100,000 (age-standardised 48) when applying the 1993 definition, and the difference was more pronounced at older ages. The incidence of all first seizures and of seizure mimics was 102 per 100,000 (age-standardised 123) and 94 per 100,000 (age-standardised 111), respectively. The most frequently encountered seizure mimic was syncope.

Conclusion: Application of the 2014 ILAE definition of epilepsy resulted in higher incidence of new diagnosis of epilepsy compared to the 1993 definition. The incidence of seizure mimics almost equals that of all first seizures. Seizures, epilepsy and seizure mimics represent a significant burden to healthcare systems.