Clinical Study Results: Efficacy of vagal nerve stimulation on selected patients with intractable epilepsy

Diana Moses R.N., C.N.S., M.S., C.N.R.N.; Mark Yerby M.D., M.P.H., F.A.A.N., James Schimshock M.D.
Providence Epilepsy Services, Portland, Oregon

Vagal nerve stimulation (VNS) is an adjunctive therapy for improving seizure control in patients with epilepsy. The actual mechanism for how the VNS prevents seizures is not precisely known. It is clear that it prevents the hypersynchronization of neuronal activity seen in partial and generalized seizures. VNS increases the concentration of GABA, an inhibitory neurotransmitter, in cerebral spinal fluid. In the initial clinical trials, a response rate of approximately 40% has been reported. A patient is considered a responder if they had a reduction in seizures by 50%. In our experience, patients have had more successful outcomes. This report describes the efficacy of VNS therapy in a series of intractable patients with partial and primarily generalized epilepsy. It is our belief that careful patient selection for VNS therapy will improve clinical outcomes.