Long-term follow-up of vagus nerve stimulation in drug-resistant KCNT1-related epilepsy: a case presentation

Background The KCNT1 gene encodes a Na+-activated K+channel.Gain-of-function mutations of KCNT1 lead to autosomal dominant sleep-related hypermotor epilepsy,early-onset epileptic encephalopathy,focal epilepsy and other epileptic encephalopathies.In this paper,we report a boy carrying a KCNT1 gene mutation,who presented with drug-resistant focal-onset seizures.He had decreased seizure frequency and improvement of background changes in electroencephalography(EEG)after vagus nerve stimulation(VNS).Case presentation The case was a nonverbal 9-year-old male who presented with drug-resistant focal-onset seizures since age 3 and had underwent VNS therapy for 2 years.He had hypermotor symptoms,automatism and bilateral asymmetric tonic seizures with cognitive decline and aphasis from age 3.The patient had a variety of seizure types that only occurred at night.The most common seizure type was automatisms,and ictal video EEG showed high-amplitude delta waves,followed by a fast rhythmic sharp activity in the mesial frontal and bitemporal regions.The patient was diagnosed with KCNT1-related epilepsy,epileptic encephalopathy and cognitive disorder.He was refractory to multiple anti-seizure medicines(ASM)and ketogenic diet.After VNS treatment at age 7,the frequency of seizures was reduced significantly and EEG was improved in background slowing.Conclusions Children with KCNT1-related epilepsy usually have early onset of disease,are nonverbal,and are refractory to ASM.This boy with drug-resistant KCNT1-related epilepsy showed significantly reduced seizure frequency after VNS.This report may provide reference for management of cases of KCNT1-related epilepsy.