Thank you for sharing your experience with a TENS unit. GammaCore has been a pretty big disappointment. I personally had an opportunity to give it a good try and found it utterly useless. Others report mixed results but it rare to hear a resounding positive comment. Electrical stimulation has been very popular in many areas of pain and dysfunction and a variety of delivery systems are available (TENS type units, direct contact, using acupuncture needles with signal generator attached and implantable neurostimulators.) The theory with GammaCore is to use the vagus nerve as a conduit to affect whatever events are leading to the vasodilation which may be causing the pain. The placement of the GammaCore is intended to provide focused stimulation to the Vagus nerve. By placing the patches near the jaw and behind your head many different nerves are involved and there may be unintended consequences so caution is advised. Also with nerve stimulation there are several variables that can dramatically effect the outcome including frequency, pulse width, amplitude and intensity. Depending on the settings you can get diffing results. Patch size translates to surface area and you have to be careful if the patches are reduced in size as the energy delivery will be concentrated. Be careful its not a risk free thing you are trying especially in a nerve rich head