I failed to mention in my two previous posts that there is a difference in the type of electrical current used in transcutaneous electrical nerve stimulation (TENS) and transcranial direct current stimulation. The former uses alternating current, while the latter is a direct current (AC vs DC). Cefaly device uses AC, while tDCS devices use DC. It is possible that both types of stimulation are equally effective for chronic migraine headaches and other conditions. We would need to have a blinded trial comparing these two types of stimulation to see if one is superior to the other.
