It is important to keep in mind that VNS is used in conjunction with AEDs, not instead of them. VNS may be considered as a treatment option in patients who have tried two or more anti-epileptic drugs (AEDs) without adequate control of their seizures or in patients who have not responded to AEDs and cannot undergo brain surgery. The Food and Drug Administration (FDA) approved VNS as a seizure treatment in 1997. Of these, hoarseness, coughing, throat tickling and shortness of breath are the most common and are usually temporary. Muscle movements or twitching related to the stimulation.Side effects are most commonly related to stimulation and usually improve over time. All maneuvers performed with the magnet can be done by the patient, family members, friends or caregivers. Removing it will resume the stimulation cycle. Holding the magnet over the pulse generator will turn the stimulation off while the magnet is in position. When the magnet is swept over the pulse generator site, extra stimulation is delivered regardless of the treatment schedule. Patients are provided with a handheld magnet (Magnet Bracelet, Figure 4) to control the stimulator at home (which must be activated by the physician to magnet mode). The device runs continuously and is programmed to turn on and shut off for specific periods of time - for example, 30 seconds on and 5 minutes off. The amount of stimulation varies by case but is usually initiated at a low level and slowly increased to a suitable level for the individual. The strength and duration of the electrical impulses are programmed. The treating neurologist programs the stimulator in his or her office with a small hand-held computer, programming software and a programming wand (Programming Wand, Figure 3). The stimulator is most commonly activated two to four weeks after implantation, although in some cases it may be activated in the operating room at the time of implantation. When the battery is low, the stimulator is replaced with a less invasive procedure which requires only opening the chest wall incision. The stimulator contains a battery, which can last from one to 15 years. The device or implant is a flat, round piece of metal that measures about an inch and a half (4 centimeters) across and 10-13 mm thick, depending on the model used (Pulse Generator, Figure 1). This is where the thin, flexible wires that connect the pulse generator to the vagus nerve are inserted (Lead, Figure 2). A second incision is made horizontally on the left side of the lower neck, along a crease of skin. The first one is made on the upper left side of the chest where the pulse generator is implanted (Pulse Generator, Figure 1). The procedure requires two small incisions. Other surgical risks of VNS include inflammation or pain at the incision site, damage to nearby nerves and nerve constriction. As with all surgeries, there is a small risk of infection. It is usually performed on an outpatient basis. This procedure, performed by a neurosurgeon, usually takes about 45-90 minutes with the patient most commonly under general anesthesia.
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