Depression, Depressionen

What Is Vagus Nerve Stimulation?

The term i‘agus nert‘e stimulation generally refers to several different techniques used to stimulate the vagus nerve, including those in studies in animals where the vagus was accessed through the abdomen and diaphragm. For practically all studies in humans, Vagus Nerve Stim ulation refers to stimulation of the left cervical vagus rierve using a commercial device, the NCP System (Cy beronics, Houstom Schachter and Saper 1998; Figure 3).

Vagus Nerve Stimulation has been commercially available for the treatment of resistant partial-onset seizures in epilepsy in Europe (since 1994) and in the United States (since 1997). About 6000 people worldwide with over 7000 patient years of experience have had these generators implanted (W. Duffell, Cyberonics, personal communication). Typically, epilepsy patients considering VNS have had unsatisfactory seizure control, commonly with several medications. and for some VNS is an Option before brain surgery.

In many ways, VNS delivered through the NCP System is much like the very common practice of implanting cardiac pacemakers. In both cases, a subcutaneous generator sends an electrical signal to an Organ through an implanted electrode. In fact, the surgery for implanting the NCP generator in the chest is much like inserting a cardiac pacemaker (Amar et al 1998). The two techniques differ, of course, in the site of stimulation. Vagus Nerve Stimulation with the NCP System

is delivered through an implantable. mu]tiprograrnmable, bipolar pulse generator (the size of a pocket watch) that is iniplanted in the left chest wall to deliver electrical signals to the left vagus nerve through a bipolar lead. With VNS, the electrode is wrapped around the vagus nerve in the neck, near the carotid artery using a separate incision, and connected to the generator subcutaneously. Although VNS implantation surgery was initially done almost exclusively by neurosur geons in patients admitted overnight to a hospital and given general anesthesia, more recently some epilepsy patients have had the device implanted by vascular surgeons or ear, nose. and throat specialists via outpatient surgery with local anesthesia.

The NCP programming wand and software, along with a personal computer. provide telernetric communication with the pulse generator, which enables noninvasive pro gramming, functional assessments (device diagnostics and interrogation), and data retrieval. The NCP System in cludes mechanical and electrical safety features that mm imize the possibility of high-frequency stimulation that could lead to tissue darnage. In addition, each patient is given a magnet that, when held over the pulse generator, turns off stimulation. When the magnet is removed, normal programrned stimulation resumes.