Beyond the treatment of epilepsy: new applications of vagus nerve stimulation in psychiatry.
ABSTRACT Vagus nerve stimulation (VNS) in humans generally refers to stimulation of the left vagus nerve at the cervical level VNS is an established treatment largely devoid of severe side effect for medically refractory partial onset seizures and has been used in more than 16,000 patients. Over the past 5 years, applications in other neuropsychiatric disorders have been investigated with a special emphasis on depression. Recent data from an open-label, multi-center pilot study involving 60 patients suggest a potential clinical usefulness in the acute and maintenance treatment of drug-resistant depressive disorder. The perspective of VNS as along-term treatment with the advantage of assured compliance makes it an interesting technique to potentially treat drug-resistant depression. However, definite therapeutic effects of clinical significance remain to be confirmed in large placebo-controlled trial. Results of clinical pilot studies involving patients suffering from obesity and Alzheimer's disease indicate that VNS might induce weight loss and improve cognition. Besides its clinical usefulness, VNS can be used as a research tool, allowing neurophysiologic investigations of the parasympathetic system and its interactions with other parts of the central nervous system.
Article: Vagus nerve stimulation therapy system: in vitro evaluation of magnetic resonance imaging-related heating and function at 1.5 and 3 tesla.[show abstract] [hide abstract]
ABSTRACT: Objectives. To evaluate magnetic resonance imaging-related (MRI-related) heating for the VNS Therapy System at 1.5 and 3 tesla (T) using various device configurations and MRI conditions and to assess device function before and after MRI. Methods. The VNS Therapy System (pulse generator, Model 102; leads Models 300 and 302; Cyberonics, Inc., Houston, Tex, USA) underwent assessment of MRI-related heating at 1.5 and 3 T using different positioning configurations, leads, transmit radiofrequency (RF) coils (body and head), RF power levels, and scans on different body regions. The function of the VNS Therapy System was evaluated before and after scanning. Results. At 1.5 T using a transmit RF body coil, excessive temperature changes were associated with scans of the C-spine/shoulder (+11.5°C, complete system; +29.5°C, lead without pulse generator). The lowest temperature change occurred for the scan of the L-spine. At 1.5 T using a transmit/receive RF head coil, temperature changes did not exceed +0.2°C under the conditions studied. At 3 T using a transmit RF body coil, the highest temperature change occurred with the scan of the C-spine/shoulder (+14.5°C) with the lead configured with no strain relief loops at the vagus nerve. MRI performed using various conditions at 1.5 and 3 T produced no significant alterations in the function of the VNS Therapy System. Conclusions. MRI-related heating was characterized for a variety of scenarios, identifying unsafe as well as safe conditions. Device function was unaffected by MRI procedures at 1.5 and 3 T. By following specific conditions, safety guidelines for the VNS Therapy System may be expanded beyond those currently indicated by the manufacturer.Neuromodulation 07/2006; 9(3):204-13. · 1.19 Impact Factor