Nerve Stimulation Research
When I told you in June I'd write a review of research on nerve stimulation, I imagined reading all the available research, drawing conclusions from it, and sharing a summary of the findings. I expected to wrap up the analysis neatly and include hard numbers like the percentages of patients who benefit from implanted nerve stimulators and their degree of improvement. Well, it's not that simple.
Although occipital nerve stimulation was first used for head pain in 1977 , research didn't take off until about 10 years ago. Early studies were small (all had fewer than 30 participants, most had fewer than 10, and some were case studies of one or two patients). They included patients with a variety of headache types, some of whom had medication overuse headache on top of a primary headache disorder, and did not have control groups (patients who did not receive active stimulation). Most focus on the peripheral nerves, which are located outside the brain (like the occipital, trigeminal, supraorbital), rather than those that are deep within the brain (like the vagus nerve), and, of peripheral nerve stimulation research for chronic migraine, most is centered on the occipital nerve. There’s no tidy way to round them up.
Early studies were interesting enough to prompt more research, but in no way did they "prove" nerve stimulation was an effective treatment for chronic migraine. Even now, with results from larger scale studies that include control groups, the findings are still preliminary. While a chronic migraineur who believes they're nearly out of options may be tempted to latch onto these studies as an indication that nerve stimulation is their miracle treatment, a scientist would say these are merely interesting results that should prompt further investigation.
I'll summarize the most recent published results from migraine-specific studies with the largest number participants. The peer review process is a critical step in evaluating the validity and credibility of research findings, so I'm focusing only on peer reviewed journal articles. I do not include conference presentations as they are often works-in-progress and have yet to undergo peer review.
Occipital nerve stimulation is the focus of both studies summarized below. While some patients report anecdotal success with stimulation to both the occipital and supraorbital nerves, studies on this type of stimulation have yet to be published. That doesn’t mean the treatment isn’t promising, just that the research is in it’s infancy.
Safety and Efficacy of Peripheral Nerve Stimulation of the Occipital Nerves for the Management of Chronic Migraine: Results from a Randomized, Multicenter, Double-blinded, Controlled Study
Silberstein S.D., Dodick D.W., Saper J., Huh B., Slavin K.V., Sharan A., Reed K., Narouze S., Mogilner A., Goldstein J., Trentman T., Vaisma J., Ordia J., Weber P., Deer T., Levy R., Diaz R.L., Washburn S.N., Mekhail N.
Cephalalgia, 2012 Dec; 32 (16): 1165-79.
Participants: 105 participants with active stimulators, 52 with sham stimulators
- chronic or probable migraine
- at least 15 headache days a month
- unsuccessfully tried at least two migraine abortives and two migraine preventives
Findings: There was little difference between the active and sham groups when measuring the primary endpoint (the main result measured), which was a 50% reduction in pain as reported on a specific pain scale 12 weeks after the device was implanted. However, researchers point out that more patients who received active stimulation reported a 30% reduction in pain than those with sham stimulation. The active group also reported fewer headache days, less migraine-related disability, and reported pain relief than those in the sham group.
Occipital Nerve Stimulation for the Treatment of Intractable Chronic Migraine Headache: ONSTIM Feasibility Study
Saper J.R., Dodick D.W., Silberstein S.D., McCarville S., Sun M., Goadsby P.J.; ONSTIM Investigators.
Cephalalgia, 2011 Feb; 31 (3): 271-85.
Participants: 75 participants were either implanted with a stimulator they could adjust themselves, implanted with a stimulator with a preset stimulation level, or were placed on medical management. Of the 75 participants, 66 submitted completed diaries, which were part of the analyzed data.
- 15 or more headache days per month
- No medication overuse headache
- No other potential headache diagnosis
- Headache pattern had to be present for at least one year (the average was 10 years)
- Had not responded to at least two classes of medication
Findings: After three months, 39% in the adjustable stimulation group reported either a 50% or greater reduction in the number of headache days per month of at least a three-point reduction in their overall pain intensity on a 1-10 scale. In the preset stimulation group, that reduction was 6% and it was 0% in the medical management group. Lead migration occurred in 24% of participants.
The hard numbers in these studies aren't astounding, especially considering the surgery and having an implanted device aren't without risks, like leads breaking or migrating, battery failure, and pain or numbness at the battery or lead site. However, nerve stimulation is intended for patients with frequent, severe migraine that hasn't responded to conventional treatments and who are desperate for relief. The numbers might not be high in the realm of clinical research, but in the daily lives of people with chronic migraine, that could be huge.
It's all a matter of weighing risks versus rewards. In my third and final installment on nerve stimulation this summer, I'll help you figure out how to determine exactly what those risks are and if you’re a good candidate for the surgery.
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