Promising pilot results for prefrontal rTMS treatment of fibromyalgia “suggestive” but “inconclusive”
MedWire: An initial study of prefrontal repetitive transcranial magnetic stimulation (rTMS) as a treatment for fibromyalgia has produced mixed results regarding efficacy, prompting calls for further research into the treatment.
Baron Short (Medical University of South Carolina, Charleston, USA) and colleagues conducted preliminary research into the use of left prefrontal rTMS in modulating daily pain in patients with fibromyalgia. Their study, published in the journal Pain, involved 20 patients, divided equally and randomly into a group that received active treatment and a sham-treatment group.
All patients received 10 treatment sessions over 2 weeks. Patients in the rTMS group were treated with 4000 pulses at 10Hz TMS.
The patients recorded their daily pain, mood, and activity levels, along with blinded assessors who also rated these variables, plus tender points, in the patients weekly according to the Brief Pain Inventory, Hamilton Depression Rating Scale, and Fibromyalgia Impact Questionnaire.
They found that the rTMS-treated group had significantly reduced daily pain levels at the end of the study period compared with baseline, and there were no such reductions in the sham-treatment group over the study period. Patients that received rTMS experienced a 29% reduction in pain; however, pharmaceutical trials for fibromyalgia require a 30% reduction for clinical significance.
There was no significant difference in mean pain reduction between the rTMS group and the sham-treatment group.
"Thus, any conclusions of fibromyalgia pain reduction with TMS are premature until studies with larger sample sizes show differences between groups, not just pain reduction over time from baseline measures," acknowledge the researchers.
In an accompanying commentary, Neil O'Connell of Brunel University in London, UK, calls the results "suggestive, but ultimately inconclusive." He says that "this study joins an array of similar small exploratory studies of rTMS for the treatment of chronic pain," but that these lack sensitivity and are therefore insufficiently powered.
After drawing together data from existing rTMS studies, O'Connell writes that the effects of rTMS are not clearly beneficial, which could be due to a number of possible reasons.
"A change of priorities for [noninvasive brain stimulation] clinical research in chronic pain is required and would be timely," he says, adding that the need is "urgent." He specifically called for "robust" examination of "the promising findings within the existing data through large, rigorous, adequately blinded trials that deliver a reasonable dose and investigate effects over a meaningful timescale."
By Chloe McIvor