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VNS Therapy is the first treatment approved by the FDA for both medically refractory epilepsy and depression. The safety profiles for VNS Therapy and the VNS Therapy System, including the implant procedure, are well established in clinical studies of refractory epilepsy and depression and in commercial use in over 52,000 patients.
The VNS Therapy System is a proprietary, integrated system consisting of an implantable generator that delivers an electrical signal to an implantable lead attached to the left vagus nerve. The vagus nerve is the longest of the cranial nerves, extending from the brain stem through the neck to organs in the chest and abdomen. The left vagus nerve has been shown to have influence over numerous areas of the brain. Preclinical studies and mechanism-of-action research suggest that intermittent stimulation of the left vagus nerve in the neck modulates a number of structures and alters blood flow bilaterally in several areas of the brain. These studies have also shown that stimulation of the left cervical vagus nerve is effective in suppressing the intensity or frequency of seizures and results in persistent or carryover antiepileptic effects, which increase with chronic intermittent stimulation. The mechanism-of-action research associated with our depression studies has shown stimulation of the left vagus nerve results in modulation of areas of the brain thought to be important in the regulation of mood.
The VNS Therapy System consists of a pulse generator, a bipolar lead, a programming wand and software and a tunneling tool. The pulse generator and bipolar lead are surgically implanted in a procedure that takes from 60 to 90 minutes, during which time the patient is under general, regional or, rarely, local anesthesia. The pulse generator is surgically implanted in a subcutaneous pocket in the upper left chest. The bipolar lead is connected to the pulse generator and attached to the vagus nerve in the lower left side of the patient's neck.
The VNS Therapy System delivers stimulation on a chronic, intermittent basis. The initial stimulation parameters that we typically recommend are a 30-second period of stimulation, which we refer to as ON time, followed by a five-minute period without stimulation, which we refer to as OFF time. To optimize patient treatment, the current pulse width, amplitude and frequency and stimulation ON and OFF intervals of the pulse generator can be adjusted non-invasively by the treating physician with a handheld computer using our programming wand and software. In addition, epilepsy patients can use a small, handheld magnet provided with the VNS Therapy System to activate or deactivate stimulation manually. On-demand therapy can be useful for those epilepsy patients who sense an oncoming seizure and has been reported by a number of patients to abort or reduce the severity or duration of seizures. The magnet can also be used to provide epilepsy patient control of stimulation side effects by allowing the patient to deactivate stimulation temporarily.
Source: Cyberonics Inc., 10-K, filed 6/24/2008
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