Fig. 1

schematic representation of the VNS therapy system. Study participants will be implanted with the VNS Therapy system that includes a small pulse generator surgically implanted subcutaneously in the thoracic area (usually the left side) and a thin, flexible wire called a lead that connects to the vagus nerve (Fig 1). Mild intermittent electrical stimulation is delivered to the vagus nerve eliciting action potentials in the vagal fibres that synapse in the brainstem. Clinicians are able to program the system using an external programming device relying on attentive patient-specific titration to select the right combination of adjustable parameters (output current, frequency, pulse width, and signal ON and OFF times) to attain full activation of the vagus nerve while minimizing stimulation-induced side effects. Additional information is provided in the VNS Therapy Physician’s Manual and the Implant Manual