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Editor,—It is timely that “Archivist” has taken an interest in vagal nerve stimulation for epilepsy. The comments do not suggest however that Archivist was fully informed.
It is true to say that the mechanism by which the effect is achieved is not known, but there is considerable animal evidence that both serotoninergic and noradrenergic pathways from afferent vagus terminations to the thalamus are involved.1
It is also true to say that data on efficacy in children have not been controlled. While one of the multinational trials compared low versus high stimulation,2-4 it is not possible to design a fully controlled trial for a treatment which involves a surgical procedure and in which the patient is aware of stimulation.
Archivist rightly emphasises that the most important question is whether the children were better off for the intervention. We have attempted to answer this question in a study of children with epileptic encephalopathy in which outcome measures included not only seizure frequency, but also cognitive function and quality of life measures.5 6 At two years, there was a median seizure reduction of 43% with five of 15 children achieving a more than 60% reduction in seizure frequency and a further three, a 40% to 60% reduction. Adaptive behaviour (a measure of learning) was unchanged, although verbal skills significantly improved in six more able children. Quality of life measures did not improve in most areas except in perceived treatment side effects and general behaviour at one year. All but two families were pleased that the children had had this form of treatment. The reason for this was that all children without exception were more alert, happier, and more interested in interacting.
The three year results are less encouraging with regard to seizure control. The effects on affect and behaviour have been sustained. We are currently investigating the possible causes for relative loss of seizure control. Meanwhile, I would suggest that the subject has evolved considerably further than cerebellar stimulation did some 25 years ago.
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