Peripheral neuromodulation and headaches: history, clinical approach, and considerations on underlying mechanisms. (2013)

From the Review:

“With the publication of their “Gate Control Theory” of pain modulation in 1965, Wall and Melzack provided a conceptual mechanistic foundation for considering direct electrical stimulation of the spinal cord and peripheral nerves as a potential treatment for chronic pain…”

“This is very important, as the clear clinical standard used to define a positive response to a trial stimulator is over 50 % improvement. Thus, of the three largest, double-blinded, prospective studies that have been performed to date on ONS [occipital nerve stimulation] and migraine, two found no significant support for an adequate therapeutic effect, and the other found only a very qualified 39 % success rate.”

“Based on several convergent lines of consideration (see below), in 2006 we hypothesized that using combined ONS and SONS [supraorbital nerve stimulation] may be beneficial in some patients suffering from chronic migraine, where the pain is perceived in hemicephalic or global extent (and therefore involving both the trigeminal and occipital neural systems), and in 2009, we reported on strongly positive responses in a series of seven patients so treated. All were quite debilitated due to daily incapacitating migraine, and all responded, with six describing near complete resolution of the headaches (over 90 % improvement).”

“All five individual “concordant paresthesia” groups of Table 1 reported very high and consistent response rates (88 %, 89 %, 89 %, 98 % and 100 %, respectively) for an overall response rate of 93 %. These results stand in sharp contrast to those found in Table 2, which are those of the groups studying implants that produce non-concordant paresthesias, which overall found less than a 40 % response rate.”

“It is this dramatic difference in the observed success rates that provides such compelling support for the central importance of paresthesia concordancy.”

My comments:

The abstract of this paper didn’t do it any justice so I’m quoting excerpts I thought most interesting. For anyone interested in the treatments of headaches, the entire paper  is a must-read. The study is in regard to peripheral nerve stimulation (PNS), which is the surgical implantation of electrodes to stimulate various nerves and decrease pain. I’ve blogged about PNS before and applied it to my transcutaneous electric stimulation for headaches with good result. What researchers found was occipital nerve stimulation (ONS) (at the posterior upper neck/base of the skull region) had about 40% effectiveness on migraine headaches. While reasonably good, this was less effect than they found with PNS of other neuralgias. What they noticed was that migraine pain was more frontal, so they added supraorbital nerve stimulation (SONS) (on the forehead above the eyes) which raised the effectiveness for treating migraines to >90% which was about the same as they were achieving with PNS of other neuralgias.

As I noted in an earlier blog I was acutely decreasing non-specific headache pain 76% with non-invasive transcutaneous stimulation to the occipital region only. I have been happy with that result, and for the most part so have my patients. However, it was still sometimes only marginally effective, perhaps because I was not getting “paresthesia concordancy” (meaning the tingling from the electrodes was not covering the entire region of headache pain). So going forward, my next 20+ patients are going to be getting my electric stimulation protocol with electrodes both on the ONS and SONS region.  We will see if there is a greater effect, and if that greater effect relates only to frontal headaches or non-specific headaches.

A word on safety:  I have been hesitant to place electrodes directly on the head of patients with headaches.  However recently the FDA just approved the use of the Cefaly device, which is a TENS unit on a headband, with electrodes placed directly over the supraorbital region. Safety was established based on a study of 2313 headache sufferers without any serious adverse events, so transcutaneous supraorbital stimulation appears safe if you follow certain parameters. Those parameters were a pulse duration of 250 uS, max intensity of 15 mA, and a rate of 60 Hz, all of which I want to talk more about in my next blog.