One-year seizure freedom and quality of life in patients with drug-resistant epilepsy receiving adjunctive vagus nerve stimulation in Japan.

Abstract

Amount of seizure-free days is a critical determinant of quality of life (QoL) in patients with drug-resistant epilepsy (DRE). The fractions of patients experiencing prolonged periods of seizure freedom with adjunctive vagus nerve stimulation (VNS) have yet to be assessed on a large scale. Retrospective analysis of patients in the Japanese VNS prospective observational registry who experienced at least 1 year of seizure freedom from all seizures, focal seizures, or tonic-clonic seizures (TCS), as well as patient-reported change in QoL in these groups. The study included 362 patients with DRE, 147 were female (40.6%), and the median age at VNS implant was 23.0 years (range: 1.0-73.0). A total of 225 patients reported focal seizures and 184 patients reported TCS. After 36 months of adjunctive VNS, the cumulative proportion of patients experiencing at least 1 year of complete seizure freedom was 11% (38/356) with an average duration of seizure freedom of 19.4 months. In patients with focal seizures, 25% (n = 57/225) experienced at least 1 year of freedom from focal seizures with an average duration of 24.8 months. Higher cumulative rates of freedom from TCS were observed: 55% (n = 101/184) experienced at least 1 year without TCS with an average duration of TCS-free periods of 28.9 months. 82.1% of patients with 12-month complete seizure freedom reported markedly improved or improved QoL compared with 51.9% of patients who were not seizure-free. QoL changes in patients with 12-month seizure freedom from TCS and focal seizures were similar: 61.8% and 63% of respective patients reported either markedly improved or improved QoL at 36 months. Complete seizure freedom is rare in patients treated with VNS; however, this analysis found approximately half of patients who experienced TCS prior to VNS experienced prolonged periods of freedom from TCS with adjunctive VNS. We studied patients in Japan with epilepsy that is difficult to treat. To understand if adding vagus nerve stimulation (VNS) helps such patients, we looked at which patients stopped having all seizures or stopped having a specific seizure type (such as tonic-clonic seizures or focal seizures), and how long these periods lasted. With VNS treatment, about 2 out of 4 patients with tonic-clonic seizures and 1 out of 4 patients with focal seizures had more time without these seizure types. Without seizures, patients felt better about their daily lives. Even patients who still had seizures felt better about their daily lives after 3 years of VNS treatment. The clinical trial registry number is UMIN000014728.