Treatment with an experimental noninvasive cortical electrostimulation technology that targets areas of the brain involved in abnormal pain processing shows efficacy in reducing fibromyalgia symptoms, a new study shows.
With the help of neuroimaging advances in recent years, researchers have been able to identify correlates between brain activity, abnormal pain processing, and augmented neural connectivity in pain networks.
The technology, dubbed reduced impedance noninvasive cortical electrostimulation (RINCE), sends high-frequency signals delivered through noninvasive electrodes resting on the scalp into deeper cortical tissues.
"These findings provide a scientific rationale for brain-targeted therapies such as device-based cortical stimulation," the researchers, with lead author, Jeffrey B. Hargrove, PhD, an associate professor of mechanical engineering at Kettering University in Flint, Michigan, conclude.
Their results were presented on Pheonix at the American Academy of Pain Management (AAPM) 23rd Annual Clinical Meeting.
In the randomized, controlled trial, 77 patients with fibromyalgia were recruited, under institutional review board approval, to receive biweekly RINCE treatments over 11 weeks (n = 39) or a sham treatment (n = 38).
Because the RINCE signal causes no cutaneous sensation, the sham treatment was created by not delivering a signal. Each treatment lasted 11 minutes.
The patients were required to have primary fibromyalgia according to American College of Rheumatology criteria.
The patients were evaluated at baseline and at the end of the study using the Fibromyalgia Impact Questionnaire (FIQ), the Short-Form-36, and tender-point assessment.
At the end of the 11-week treatment, FIQ scores and subscales in pain, fatigue, sleep, and function all showed significant improvement in the RINCE group (change, -15.5; P < .001) but not in the sham group (change, -5.6; P > .05).
The intergroup outcomes were also significantly greater in the RINCE group in terms of FIQ score, pain, fatigue, and sleep subscales (P = .02 - .03).
Patients in the RINCE group also had a decreased number of positive tender-point assessments (change, -7.4; P < .001), whereas no change was seen in the sham group (change, -0.2; P = .68).
Among the 64% of surveys mailed at the 45-month follow-up study, the mean FIQ scores were 53 at baseline, 36 at the end of the study, and 32 at follow-up (P < 0.001).
The sustained improvement at 45 months was particularly remarkable, said Dr. Hargrove.
"At the follow-up, we saw no reversion — the patients that got better were still better 45 months later — this was after just the one course of 11 weeks of therapy involving 22 applications."
The respondents reported improvements lasting at least two years in pain (68%), sleep (56%), and fatigue (60%); reduced or eliminated medicine use for pain (76%); and need to see physicians for fibromyalgia (71%).
"We saw very high numbers in terms of patient self-reports in changes in reduction or complete elimination of pain medicine use — that was about 76%," Dr. Hargrove noted. "And we were also very excited to see that about 71% reported either complete elimination or reduction of caregiver visits for their fibromyalgia."
"In addition, we asked patients if they had started any of the approved drugs after the study and only one person reported starting a new drug, so that was also exciting to us."
There were no reports of significant adverse events or long-term side effects. About 5% reported headache that rapidly resolved, but the percentage was about the same in the sham group, Dr. Hargrove noted.
Pain specialist Lawrence D. Robbins, MD, from the Robbins Headache Clinic in Northbrook, Illinois, commended the research, saying the study merits further investigation.
"This was a nice study on cortical stimulation, which is similar to repetitive transcranial magnetic stimulation (rTMS)," Dr. Robbins said.
"The study was done well, and two years is a very long, excellent time for follow-up," he added. "It is a safe therapy (and looks) very promising."
"The only problem is cost," Dr. Robbins noted. "In our experience with TMS for depression, insurances do not cover it, and cost keeps the vast majority of patients from getting the therapy."
The only approved cortical stimulator on the market is rTMS, and it is approved for drug-resistant depression. Dr. Hargrove noted that RINCE has some important differences that set it apart from rTMS.
"This is not rTMS — what rTMS does is tries to induce current flows in the cortex by pulsing it with magnetic pulses and that induces current," he explained. "Instead of pulsing with magnetics, we just deliver the current directly, so it's sort of the same outcome but without the big magnets and the problems with them."
The study was supported by the McLaren Foundation and Kettering University. Dr. Hargrove is a chief scientific officer at Cerephex, which is developing the device. Dr. Robbins has disclosed no relevant financial relationships.
American Academy of Pain Management (AAPM) 23rd Annual Clinical Meeting. Poster Abstract 42. Presented September 22, 2012.
Nancy A. Melville • Medscape Medical News © 2012 WebMD, LLC