The Efficacy of Vagus Nerve Stimulation in Intractable Epilepsy Associated With Nonketotic Hyperglycinemia in Two Children

Abstract

Nonketotic hyperglycinemia is an inborn error of glycine metabolism and these patients frequently suffer from intractable epilepsy despite treatment with sodium benzoate, dextromethophan, and multiple anticonvulsants. We encountered 2 infants with nonketotic hyperglycinemia whose intractable generalized convulsive seizures were difficult to control with sodium benzoate, dextromethophan, and multiple anticonvulsants. However, after the addition of vagus nerve stimulation, their intractable generalized seizures were >75% reduced in frequency, the numbers of multiple anticonvulsants were reduced, and the quality of life significantly improved. The efficacy in seizure reduction persists for at least 3 years in both children.

Does emergent implantation of a vagal nerve stimulator stop refractory status epilepticus in children?

“…Concerning the etiology of SE, actually we cannot define a possible strong indication to emergent VNS versus conventional intensive AED treatment; in detail, VNS usually stopped R-SE or RS-SE in case of structural, genetic and metabolic pathologies, without any prevalence of clinical efficacy. Particularly, our data confirm the observation of Tsao [17] who reported two cases of NKH patients treated with left VNS with good results: the first reduced seizure frequency up to 75% and the later became seizures free. Although Zeiler F.A.…”

Efficacy of vagus nerve stimulation in a young infant with early myoclonic encephalopathy associated with nonketotic hyperglycinemia

“…Both children were reported to have greatly benefited from VNS insertion, with > 75% reduction in seizure frequency in one, and seizure remission in the other [3]. Although both patients were diagnosed with NKH, they differed from our patient as both had structural abnormalities on their brain magnetic resonance imagings and the history of at least one child is not compatible with the diagnosis of EME [3]. In addition, the frequency of seizures in those two children at the time of implantation was substantially lower than in our patient [3].…”

“…Although no evidence of efficacy of VNS in EME was available at the time of insertion, this treatment modality was tried because of the near continuous seizures that failed to respond to conventional treatment and with the approval of his parents. A report of two children with refractory epilepsy secondary to NKH, implanted with a VNS at the ages of 21 mo and 6 yr, has since been published [3]. Both children were reported to have greatly benefited from VNS insertion, with > 75% reduction in seizure frequency in one, and seizure remission in the other [3].…”

“…A report of two children with refractory epilepsy secondary to NKH, implanted with a VNS at the ages of 21 mo and 6 yr, has since been published [3]. Both children were reported to have greatly benefited from VNS insertion, with > 75% reduction in seizure frequency in one, and seizure remission in the other [3]. Although both patients were diagnosed with NKH, they differed from our patient as both had structural abnormalities on their brain magnetic resonance imagings and the history of at least one child is not compatible with the diagnosis of EME [3].…”

Vagus Nerve Stimulator in a Patient with Adenylosuccinate Lyase Deficiency: a Case Report

“…One patient achieved seizure freedom and was able to be weaned off all anticonvulsants, while the other patient had a greater than 75% reduction in seizure frequency. 14 Arthur et al reported a small retrospective case series of five children who had VNS implanted as treatment of epilepsy associated with electron transport chain deficiency type of mitochondrial disease. This study did not find VNS helpful in reducing the seizures of these children and concluded that VNS may not be an effective treatment in patients with epilepsy secondary to mitochondrial disorders.…”