This is merely an overview of VNS. For more information, please visit www.vnstherapy.com - a website of the manufacturers of the device.
Please note that VNS is no longer funded as part of our Service Level Agreement. This means that whilst Scottish NHS Boards can make a referral for consideration for specialist treatment at no additional cost, if VNS is the preferred option additional funding will be required.
VNS was postulated as a method of stimulating higher brain activity as early as 1938. The first human VNS implant was performed in 1988 for treatment of epilepsy. Since that time, VNS has become established for treatment-resistant partial onset seizure disorder, with over 15,000 patients having received implants worldwide by mid-2003.
The vagus nerve is the longest of the cranial nerves, deriving its name from the Latin for 'wandering'. It runs from the brain stem through the neck, thorax, and abdomen. It carries signals responsible for controlling smooth muscle in the lungs and gastrointestinal tract, and is responsible for slowing down heart rate.
However, the vagus nerve is not only a parasympathetic efferent nerve. 80% of its fibres are sensory fibres, transmitting information from the body to the brain. These fibres carry information to the brain stem, and on to the forebrain, amygdala, hypothalamus, thalamus, orbitofrontal cortex, and other parts of the limbic system involved in the regulation of mood.
VNS was postulated as a method of stimulating higher brain activity as early as 1938. The first human VNS implant was performed in 1988 for treatment of epilepsy. Since that time, VNS has become established for treatment-resistant partial onset seizure disorder and by 2004, more than 28000 epilepsy patients in 24 countries have been treated with VNS.
VNS involves subcutaneous implantation of a pulse generator, of a similar size and in a similar location to a cardiac pacemaker. Bipolar electrodes extend from the device and are wrapped around the left cervical vagus nerve in the neck, near to the carotid artery. In most cases, the stimulator will be on for 30 seconds every five minutes but the frequency and intensity of the stimulation is controllable using a telemetric wand connected to a palmtop computer.
So far, the number of patients which comprise the world literature is comparatively small.
A summary of published research on VNS can be found on our VNS Research page.
VNS is generally well tolerated. Some patients will, however, experience some adverse effects in the early stages of treatment. Almost invariably, these adverse effects are associated with the times that the stimulator is on (30 seconds every 5 minutes). At 3 months, common side effects include the following:
At 12 months, most adverse effects have reduced, with the exception of voice alteration which may still persist in up to 21% of people. Changing the frequency or intensity of stimulation can improve adverse effects, and patients are also given magnets which can temporarily switch off the stimulator when held over the device.
There are isolated reports of cardiac effects of VNS, with asystole occurring in 0.1% of cases when the stimulator is first turned on. No fatalities or long-term sequelae have occurred.
Psychiatric adverse effects are uncommon, although there have been two cases of mania in 30 patients receiving VNS for treatment-refractory depression (Marangell, Rush, George, et al, 2002).
Recent media coverage in VNS has undoubtedly stimulated interest in this new therapy for treatment-refractory depression. We recognise that these 'success stories' can be very attractive for people who have been suffering from chronic depression, but it is important to remember that we are more likely to hear from those people for whom it has worked.
For those wishing further information on VNS in Dundee, we suggest that you read our VNS Frequently Asked Questions.
In the first instance, we would suggest reading some of the material available on the web. Useful places to start include:
www.vnstherapy.com - information about VNS therapy (most information is about epilepsy)
www.cyberonics.com - the website of the company who manufacture the device
No. All patients must be referred by their consultant psychiatrist. Unfortunately, referrals from GPs or other healthcare professionals are not accepted since a post-operative care plan needs to be in place.
Patients from Scotland can be assessed for VNS at no additional cost since it might just be one of a variety of options to be considered. However, if VNS is the preferred choice, funding will be required even for Scottish patients. We would suggest that psychiatrists look into the possibility of VNS being funded *before* referral since there may be significant delays in funding being approved.
For patients out with Scotland, VNS has to be funded by the patient's local NHS Trust. Before someone can be assessed, the NHS Trust will have to agree funding for assessment. Due to the relative expense of VNS, many NHS Trusts won't readily approve funding. Patients attending Dundee cannot self-fund for VNS.
More than most other treatments for depression! The overall cost has to take into account extensive pre-operative assessment by neuropsychologists, psychiatrists, and psychologists, as well as a period of inpatient stay in hospital. Follow-up is typically for 3-5 years, and patients have to attend Dundee regularly in the initial stages for programming of the device and optimisation of the stimulating parameters.
We conduct detailed assessments of all previous treatment approaches and review the patient, typically in Dundee. Thereafter, we advise on management options that should be explored. Only sometimes does this involve Vagus Nerve Stimulation and any assessment would be conducted on the basis that we would provide our overall clinical opinion rather than specifically focusing purely on Vagus Nerve Stimulation.
The number of previous treatments which should have been tried is not as high as for ablative neurosurgery. However, it is expected that the individual is demonstrably resistant to a variety of different classes of antidepressants (at least four), as well as having had a course of psychological treatment (e.g. CBT or IPT) which has been unsuccessful.
Although they are just a guide, there are criteria for suitability for VNS.
At this time, Vagus Nerve Stimulation should be considered as an experimental treatment. Although it shows promise, there is still relatively little information available about its overall effectiveness in the long term and when it might best be used. Some outcomes from published research are given on our general VNS page. It is important to remember that there is far more evidence for established treatments for depression such as antidepressants, cognitive behavioural therapy (CBT), and electroconvulsive therapy (ECT).
There is much less evidence to support VNS as a treatment for bipolar depression and it isn't clear what the role of VNS might be. We would encourage potential referrers to discuss it with us. Assessments will be conducted on a case-by-case basis.