Seizure Cycles under Pharmacotherapy

Area of Science:

• Epilepsy research
• Neuroscience
• Pharmacology

Background:

• Pharmacoresistant focal epilepsy presents a significant clinical challenge.
• Interictal epileptiform activity (IEA) cycles and seizure frequency are key metrics in epilepsy management.
• The impact of antiseizure medications (ASMs) on long-term IEA patterns and seizure control requires further elucidation.

Purpose of the Study:

• To investigate the effects of ASMs on multiday (multidien) cycles of IEA and seizures in adults with pharmacoresistant focal epilepsy.
• To evaluate the clinical significance of changes in IEA cycle strength as a predictor of seizure control.
• To assess the utility of IEA as a potential biomarker for predicting ASM treatment response.

Main Methods:

• Retrospective analysis of up to 10 years of data from 88 adults with pharmacoresistant focal epilepsy using RNS System intracranial device data.
• Evaluation of changes in self-reported disabling seizures and multidien IEA cycle strength (4-40 day periodicity) following adjunctive ASM trials.
• Application of survival analysis and receiver operating characteristic curves to assess IEA changes as a predictor of seizure control.

Main Results:

• Adjunctive ASM introduction led to a 50-70% decrease in multidien IEA cycle strength and a concomitant 50-70% decrease in relative seizure rate for up to 12 months.
• A ≥50% decrease in IEA cycle strength within the first 3 months of ASM treatment predicted a higher probability of remaining seizure responders (≥50% reduction) or super-responders (≥90% reduction) over 12 months.
• IEA cycle strength changes were found to be a significant predictor of long-term seizure response.

Conclusions:

• A reduction in multidien IEA cycle strength following ASM initiation correlates with seizure control for up to 12 months in pharmacoresistant focal epilepsy.
• IEA fluctuations appear to mirror 'disease activity' in this patient population.
• IEA cycle strength holds potential clinical utility as a biomarker for predicting ASM treatment response.