Great question! I spoke with the Cerbomed folks when they came out with their stimulator. At the time, I was suspecting vagus nerve compression. If the nerve is compressed or damaged for any reason, stimulation is not going to help it, and the folks at Cerbomed agreed. When I noticed that most of us had many symptoms of low acetylcholine, I realized that THAT was the likely cause of poor vagus nerve functioning in most of us. To correct it, we came out with Parasym Plus (www.VagusNerveSupport.com) to stimulate the postganglionic portion of the nerve (the second piece, if you will). I hope that helps!