Vagus nerve stimulation in KCNB1-related developmental and epileptic encephalopathy: A case of seizure reduction and review of literature

Developmental and epileptic encephalopathies (DEEs) are devastating syndromes characterized by early-onset, treatment-resistant seizures, and significant developmental delays. <i>KCNB1</i>-related DEE, arising from pathogenic variants in the <i>KCNB1</i> gene, presents with profound cognitive impairment and persistent seizures despite multiple antiseizure medications (ASMs). Vagus nerve stimulation (VNS) has emerged as a valuable adjunctive therapy for medically intractable epilepsy, yet its effectiveness in rare genetic DEEs remains unknown. We report the first case of VNS in a 5-year-old child with <i>KCNB1</i>-related DEE, achieving about 90% seizure reduction after one year. Prior treatments with multiple ASMs had minimal effect. After VNS implantation, optimized stimulation parameters combined with fenfluramine markedly improved seizure control. Although concurrent medication adjustments and transient seizure cessation during infection complicated interpretation, the sustained seizure improvement strongly suggests VNS's efficacy in this genetic epilepsy. This case illustrates VNS's potential benefit and possible synergy with fenfluramine in <i>KCNB1</i>-related DEE. Further accumulation of case reports is necessary to confirm these findings.