FCS associated with reduced seizure frequency in drug-refractory focal epilepsy

05 Jun 2023

In a recent pooled analysis of 2 prospective, multicenter, single-arm clinical trials, the effectiveness and safety of focal cortex stimulation (FCS) with an epicranial implantable electrode array were investigated.1 The results highlighted FCS’s potential in inducing a significant reduction in seizure frequency among patients with drug-refractory focal epilepsy.1 

Despite the use of antiepileptic drugs, sufficient response to drug therapy among focal epilepsy patients may be unachievable.1 A 30-year longitudinal cohort study showed that approximately 36.3% of patients were incapable of achieving 1 year of seizure freedom under drug therapies.2 Since many of these patients are not candidates for surgery, alternative treatment plans are needed.  

A recent pooled analysis of 2 non-randomized trials, namely the EASEE II trial and the PIMDES I trial, was conducted to investigate the effectiveness and safety of FCS with a novel implantable device in drug-refractory focal epilepsy patients.1 Eligible patients were aged 18 to 75 years, with focal-onset seizure uncontrolled by at least 2 antiepileptic drugs, 3 or more seizures per month and a predominant epileptic focus that was temporolateral or extratemporal in origin.1 Between January 2019 and November 2020, a total of 34 patients were enrolled to receive the neurostimulation device implanted epicranially above the epileptic focus region and a pulse generator implanted subcutaneously in the pectoral region.1 Post-implant seizure frequencies and adverse effects (AEs) were recorded for assessing the efficacy and safety of FCS.1 The primary endpoint was treatment response defined as 50% reduction in seizure frequency in 6 months, while the secondary outcomes were seizure frequency, seizure severity, and treatment safety.1 Additionally, questionnaires were utilized to determine the treatment’s effects on patients’ quality of life.1 

The results showed that FCS was associated with an effective reduction in seizure frequency among patients with drug-refractory focal epilepsy.1 After 6 months of implantation, 53.1% of patients (17 of 32) were responders (i.e., those who have achieved 50% reduction in seizure frequency).1 The responder rate increased throughout the study, and those who responded early during the first 3 months remained in response in the following 3 months.1 Specifically, when compared with the prospective baseline, FCS was associated with a 52% reduction in seizure frequency  (95% CI: 0.37-0.76%; p<0.001).1  

The results also showed a favorable safety profile of FCS. AEs were reported in 75.6% of patients (25 of 33), but most were mild-to-moderate.1 Most of the reported AEs were resolved at month 8.1 No deaths and AEs were leading to treatment discontinuation.1 Serious AEs were reported in 21.1% of patients (7 of 33).1 Two patients were reported to have status epilepticus during the trial.1 No significant change of baseline was observed in mood and cognitive function.1 

In conclusion, the pooled data demonstrated the effectiveness and safety of FCS among patients with drug-refractory focal epilepsy, providing a promising novel option for patients with predominant epileptic focus.1 Nonetheless, additional data are required to verify the long-term benefits and effects of FCS.1 

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