Background: To report the efficacy of vagus nerve stimulation (VNS) for children and adolescents with medically intractable Dravet syndrome (DS).

Methods: Twenty-three patients with SCN1A variants and/or clinical syndromes consistent with DS, underwent VNS therapy at Severance Children’s Hospital between March 2005 and March 2018. Twenty of them, antiepileptic drugs of whose had been unchanged during 6 months after VNS implantation were enrolled. Their medical records contained a minimum of 3 months of data prior to implantation (regarding patient’s seizure types, frequency, and severity). Results: The median age at onset of epilepsy was 6.5 months old (interquartile range 5.25-10.0). In total, 17 (85.0%) patients had pathogenic SCN1A variant. The median age at VNS implantation was 11.1 years old (interquartile range 8.4-13.6). Two (10%) patients reported adverse events, such as hoarseness, deep breathing, coughing, and then had reduction of amplitude of VNS, and the others maintained 1.5/1.75. Of total 20 patients, 10 (50.0%) patients experienced a seizure reduction of 50% or more, and one (5 %) of the responders became seizure-free in 6 months. Additional 14 patients, antiepileptic drugs of whose had been unchanged during 12 months, were reviewed. Eight (57%) of 14 patients experienced a seizure reduction of 50% or more in 12 months. The responder rates got increased as time goes on after the implantation of VNS generator.

Conclusions: Adjunctive VNS in intractable epilepsy associated with Dravet syndrome appears to reduce seizure frequency.

Aggressive procedure before severe disease develops, is recommended.