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.