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About Vagus Nerve Stimulation Therapy (VNS Therapy™)
VNS Therapy is a non-pharmacologic treatment for pharmacoresistant epilepsy (i.e., epilepsy that is unresponsive to medication) and chronic recurrent treatment-resistant depression. VNS Therapy involves a small generator implanted in the left chest area, which delivers mild electrical pulses to the vagus nerve in the neck. VNS Therapy can improve seizure control and additional quality-of-life benefits for patients with epilepsy. VNS Therapy can also improve the symptoms and recurrence of treatment-resistant depression for patients suffering from TRD.
How does VNS Therapy work?
VNS Therapy sends precisely timed and measured mild electrical pulses to the left vagus nerve which then activates various areas of the brain. There is an extensive body of data that demonstrates the association between vagus nerve stimulation and brain activation. VNS Therapy is delivered via a small pacemaker-like device that is implanted just under the skin during a short, outpatient procedure. Roughly the size of a small pocket-watch, the device is implanted in the patient’s chest with small wires running under the skin to the left vagus nerve in the neck. Using an external programming system, physicians can adjust the timing and amount of the stimulation the patient receives. In epilepsy, a special magnet allows the patient/caregiver an added measure of control over their disorder by permitting extra stimulation to potentially abort or decrease a seizure.
Indications for VNS Therapy
Epilepsy
VNS Therapy is indicated for use as an adjunctive therapy in reducing the frequency of seizures in adults and adolescents over 12 years of age with partial onset seizures which are resistant to antiepileptic drugs (AEDs).
Depression
VNS Therapy is indicated for use with chronic recurrent treatment-resistant depression in a major depressive episode where patients have not responded to at least four adequate antidepressant treatments. Chronic treatment-resistant depression is defined as being in the current depressive episode for more than two years. Recurrent treatment-resistant depression is defined as having a history of multiple prior episodes of depression. The approved indication for use includes patients with unipolar or bipolar depression in a major depressive episode.
Benefits of VNS Therapy
In addition to improving the functional capacity of the patient, clinical studies have demonstrated the following benefits of VNS Therapy:
- The implant procedure is quick and simple, with a low incidence of surgical complications. The surgeon can generally perform the implant procedure in 45 minutes to an hour. Surgical complications such as infection occur at a low incidence.
- VNS Therapy is well tolerated and is associated with quality-of-life benefits. VNS Therapy is not typically associated with many of the common systemic and neurologic side effects caused by antidepressive and antiepileptic drugs such as drowsiness, lethargy, weight gain, and confusion. Studies have shown that VNS Therapy is associated with increased alertness, reduced daytime sleepiness, improved mood and improved memory.
- VNS Therapy is a targeted treatment that is not associated with the systemic toxicity sometimes caused by antiepileptic drugs (AEDs). VNS Therapy has not been shown to cause any of the more serious side effects that may occur with AEDs (e.g., bone marrow suppression, liver failure, pancreatitis, bone loss, rash, allergic reactions.)
- VNS Therapy requires a surgical procedure and cannot be used without the unanimous agreement of a patient, prescribing physician, surgeon, hospital, and payer. As a result, VNS Therapy is not likely to be used without careful and deliberate consideration as to its potential risks and benefits for each and every patient.
- Recent research suggests that earlier use of non-pharmacologic treatments, such as VNS Therapy, may result in better outcomes for patients with pharmacoresistant epilepsy. In one study, patients who had epilepsy for 5 years or less or who had been treated with four or fewer antiepileptic drugs when VNS Therapy was initiated had significant reductions in seizure frequency and experienced significant improvement in quality of life outcomes.
- Continuation rates with VNS Therapy are very high. Ninety-seven percent of patients continue with VNS Therapy at one year, and 72% at three years. These rates are much higher than are typically observed with antiepileptic drugs.
- The effectiveness of VNS Therapy does not diminish over time. In clinical studies, seizure control and quality-of-life benefits with VNS Therapy have been shown to increase over time. And over time some patients have been able to reduce the dosage or number of their antiepileptic drugs.
- VNS Therapy is easy for neurologists and psychiatrists to prescribe, control and monitor. VNS Therapy enables neurologists and psychiatrists to have a high degree of control and specificity in the treatment regimen. Because the stimulation is programmed to occur automatically and there are no pills for the patient to take, patient compliance with treatment is assured.
Common Side Effects with VNS Therapy
Common side effects associated with VNS Therapy include voice alteration, tickling in the throat, cough and shortness of breath. These side effects typically occur only during stimulation and may diminish over time. Since VNS Therapy is not a drug, it produces no drug interactions.
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