Cranial electrotherapy stimulation (CES, also known as cranial electrostimulation, or transcranial alternating current stimulation, tACS) has been used to treat
insomnia, anxiety, and depression. Previous CES devices emit current up to maximum of 1-4 mA, which is less than the 16 mA electric current delivered by Cefaly.
[reference: FDA Advisory Committee Presentation 2012]
Stimulation intensities as low as 0.2 mA were sufficient to cause brain cortical inhibition, while 1 mA increased brain neuron firing.
[tACS review: Herrmann et al 2013, tDCS review: Brunoni et al, 2012]
TENS devices are not intended to affect the brain. Generally, electrodes are placed near nerves and far away from the brain.
The Cefaly is an unique TENS device that happens to target nerves on the forehead, right over the brain.
Furthermore, the strength of electrical stimulation used is higher than other stimulation devices.[reference: Siever 2010]
Therefore, it is unclear whether a TENS device such as Cefaly that is place over the brain may in fact cause unintended brain effects.
Occipital nerve stimulation (back of head near base of skull) has been studied as treatment for chronic migraine with promising results.
[for example: Silberstein et al, 2012, Saper et al, 2011]
Trigeminal nerve stimulation (front of head. forehead above the eyes) for migraine was first studied (to our knowledge) by Reed et al, 2010 in 7 patients. It was used in combination with
occipital stimulation. The electrodes were surgically implanted in this study and the results suggested relief of chronic migraine.[reference: Reed et al, 2010]
The first published migraine studies of trigeminal nerve stimulation, using electrodes on the surface of the skin, were the two Cefaly studies published in 2013.