Effect of the revised definition of epilepsy on treatment decisions and seizure recurrence after a first epileptic seizure.

BACKGROUND: Studies on risk factors for epilepsy and seizure recurrence after a first seizure are usually based on the old definition of epilepsy with the need for two unprovoked seizures. The current definition of epilepsy allows diagnosis and treatment of epilepsy after a first seizure if the recurrence risk is >60%. We evaluate treatment decisions, seizure recurrence and risk factors for epilepsy related to the application of the new definition of epilepsy. METHODS: Data of 629 patients with a first seizure were analyzed to investigate changes of treatment decisions and seizure recurrence after the revised definition of epilepsy. We used binary logistic regression to investigate the impact of multiple factors influencing seizure recurrence like electroencephalogram (EEG) and magnetic resonance imaging (MRI) results and administration of antiseizure medication (ASM). RESULTS: The proportion of patients receiving ASM significantly increased from 70.4% to 80.5% (p = 0.015) following the new epilepsy definition, without any significant changes in the recurrence rate (40.8% vs. 45.5% after 2 years, p > 0.05). The presence of interictal epileptiform discharges (IED) in the EEG increased (OR = 1.98) and administration of ASM decreased (OR = 0.43) recurrence rates significantly. CONCLUSIONS: The new definition of epilepsy was associated with increased application of ASM, but not with reduced recurrence rates. The study confirms the presence of IED as a strong risk factor for seizure recurrence and the protective effect of ASM. The influence of imaging findings, which have a strong impact on the new definition of epilepsy, could not be confirmed.

First seizure in elderly patients: Need to treat? Evidence from a retrospective study.

BACKGROUND: The risk of seizure recurrence after a first unprovoked epileptic seizure is reported to be approximately 40%. Little is known about the recurrence risk after a first seizure in elderly patients, who may be at higher risk due to an increased rate of structural lesions, encephalopathy, subcortical arteriosclerotic encephalopathy or brain atrophy. METHODS: In a retrospective approach, the recurrence rate in 304 patients aged 60 years and above who presented with a first seizure between 2004 and 2017 was analyzed. Hierarchical Cox regression was used to investigate the impact of EEG and neuroimaging results, age or the prescription of anti-seizure medication (ASM) on seizure recurrence. RESULTS: Seizure recurrence rates were 24.5% and 34.4% after one and two years, respectively. Anti-seizure medication was started in 87.8% of patients, in 28.8% despite the absence of clear epileptogenic lesions on neuroimaging or epileptiform potentials in the EEG. Medical treatment significantly reduced the risk of recurrence (hazard ratio = 0.47). Epileptiform potentials in the EEG, epileptogenic lesions in neuroimaging and age had no significant effect on seizure recurrence. Age and the presence of neurodegenerative and psychiatric comorbidities showed a significant association with ASM prescription. CONCLUSIONS: The present data show a strong protective effect of ASM on seizure recurrence in patients above the age of 60, even in the absence of pathologic neuroimaging or EEG results needed for the diagnosis of epilepsy. Treatment with ASM therefore seems beneficial for reducing the recurrence risk in elderly patients. The lack of a significant association between seizure recurrence and epileptogenic lesions might be related to other confounding factors like encephalopathy, subcortical arteriosclerotic encephalopathy, neurodegenerative diseases or brain atrophy.