The impact of the new definition of epilepsy on diagnosis, treatment and short-term outcomes -a prospective study

Lena Habermehl ^1,2* Louise Linka ² Kristina Krause ² Alena Fuchs ² Jenny Weil ² Mariana Gurschi ³ Felix Zahnert ² Leona Möller ² Katja Menzler ² Susanne Knake ^2,4

• ¹ Epilepsy Center, Neurological Institute, University Hospitals Cleveland Medical Center, Cleveland, United States
• ² Epilepsy Center Hessen, Philipps-University Marburg, Marburg, Germany
• ³ Center for Neuroradiology, Philipps-University Marburg, Marburg, Germany
• ⁴ Center for Mind, Brain and Behavior, CMBB, Philipps-University Marburg, Marburg, Germany

Background: In 2014, the ILAE introduced a new definition of epilepsy that allows some patients to be diagnosed earlier than under the previously used definition. According to the old classification, the diagnosis was made after a second unprovoked seizure. The risk of this was 36% after the first seizure. The aim of this study is to investigate the clinical impact of the new definition on diagnosis, treatment, and short-term outcome. Methods: From 2018 to 2021, adult patients admitted with a first epileptic seizure were prospectively included. Demographic and clinical data were collected at baseline, at 6 and 12 months follow-up (FU). Factors affecting seizure recurrence, especially age, use of anti-seizure medication (ASM), interictal epileptiform discharges (IED) in the EEG, and the presence of structural lesions on imaging were investigated. Results: Data from 235 patients were collected (41.7% female). Of these, 146 patients (62.1%) were diagnosed with epilepsy (PWE), following the new ILAE-criteria. Potential epileptogenic lesions on imaging were found in 49.3% of PWE. At the first FU (6.08 months ± 1.35), 143 patients (77.3%) were seizure-free, including 89 of the 146 patients diagnosed as PWE were seizure-free (70.6%). At the second FU (12.45 months ± 1.83), 129 patients (80.6%) were seizure-free. Seventy-seven of the PWE were seizure-free (72%). The use of ASM decreased (odds ratio = 0.46, p = .004) the recurrence rate significantly.Conclusion: Our results suggest that the new definition of epilepsy results in a higher frequency of epilepsy diagnosis and treatment. Short-term outcomes improved (1-year-recurrence rate of 19.4%).