Vagus Nerve Stimulation or VNS is hampered by insufficient research. After one disappointing publication of the results of a sham controlled multi site double-blind trial in a large sample no scientific important trials are conducted. This one trial did not demonstrate superiority of active VNS treatment over sham treatments after 3 months.
Since then (2005) another trial was conducted in Europe; an open uncontrolled multi-centre study. This trial used the same protocol as the first open, unblinded four centre pilot study of 60 patients in the US.
The authors mention the argument sometimes used that it is unethical to use a controlled design with a sham condition. We are talking about patients treated with 3-7 different antidepressants and/or ECT. Mostly ill for years. I think it unethical to conduct another uncontrolled trial which will help our knowledge about the efficacy of VNS no further. Besides implanting a VNS is not peanuts nor going to a protocol of up to 1 year.
Anyway, this open study also finds that the efficacy of VNS increases over time. The follow-up in this study is up to 12 months. Again efficacy is hard to interpret since it open labeled uncontrolled design.
VNS received FDA approval in July 2005 for adjunctive, long-term use in chronic or recurrent major depression in adult patients with an inadequate response to at least four antidepressant treatments. You could say it is an option after other treatments for depression has failed
Website with a lot of information on VNS: VNSDepression.com
Related post on this blog:
5 blogposts on Vagus Nerve Stimulation (Round Up)
Psychol Med. 2008 Jan 4;:1-11 [Epub ahead of print]
Vagus nerve stimulation for depression: efficacy and safety in a European study.
Schlaepfer TE, Frick C, Zobel A, Maier W, Heuser I, Bajbouj M, O'Keane V,
Corcoran C, Adolfsson R, Trimble M, Rau H, Hoff HJ, Padberg F, Müller-Siecheneder
F, Audenaert K, Van den Abbeele D, Matthews K, Christmas D, Stanga Z, Hasdemir M.
Departments of Psychiatry and Mental Health, The Johns Hopkins University,
Baltimore, MD, USA.