Vagus nerve stimulation (VNS) and drug-resistant epilepsy: a meta-analysis
Many children are affected by drug-resistant epilepsy (DRE). Drug-resistant epilepsy can cause increased mortality, cognitive impairment/developmental delays and poorer quality of life. It is therefore important to control seizures to reduce developmental delays in paediatric epilepsy.
Seizure control may be improved by vagus nerve stimulation (VNS). VNS sends mild pulses of electricity to the brain from a device implanted under the skin in the chest, via wires that are wrapped around the vagus nerve. It has been described as a ‘pacemaker for the brain’. However, the role of VNS in children with genetic causes of epilepsy (such as TSC) has not been well studied. The authors of this paper reviewed the published research regarding VNS in children with genetically caused epilepsy.
Of the genetic conditions studied in this research, vagus nerve stimulation provided the most improvements in paediatric TSC patients with drug resistant epilepsy.
Outcomes of the research
The authors of this paper found that in children with DRE from any cause, 37.6%-64.8% responded to VNS and had a 50% reduction in seizures with the treatment.
The authors reviewed 18 studies with a total of 63 TSC patients. In this small population, VNS significantly decreased the frequency of seizures. The authors found that:
- Over two-thirds of the patients had more than a 50% reduction in seizure frequency, with a smaller portion (31%) experiencing a 90% or higher reduction in the frequency of seizures.
- Several studies on VNS in TSC related epilepsy reported decreased seizure severity and improved behavioural, functional and cognitive/developmental outcomes.
- It did not matter if the TSC mutation was TSC1 or TSC2 – VNS worked equally well in both.
- Seizure improvement or freedom was more likely to be achieved if the patient was under 12 years of age.
- Behavioural and cognitive function was most improved in children who had the VNS device implanted before 6 years of age.
Significance of this research
Whilst this was a small review with a number of limitations, it appears that VNS may increase seizure control and decrease seizure frequency in some children with TSC and drug resistant epilepsy. Increased genetic testing and diagnosis of epilepsy, alongside long-term follow-up studies will help us better understand the potential of VNS and optimize outcomes for children. This review provides an important starting point and has the potential to inform future research.
This information is intended to provide some insights into recent TSC-related research. It is not intended to, and it should not, constitute medical or other advice. Readers are warned not to take any action without first seeking medical advice.