Repetitive transcranial magnetic stimulation for fibromyalgia: are we there yet?

Repetitive transcranial magnetic stimulation (rTMS) has increasingly been used to modify cortical maladaptive plastic changes shown to occur in fibromyalgia (FM) and to correlate with symptoms. Evidence for its efficacy is currently inconclusive, mainly due to heterogeneity of stimulation parameters used in trials available to date. Here, we reviewed the current evidence on the use of rTMS for FM control in the format of a narrative review, in which a systematic dissection of the different stimulation parameters would be possible. We conducted a search in Medline and Embase for controlled trials on rTMS in people with FM with at least 10 participants in each treatment arm, and treatment/follow-up of at least 3 weeks. The search identified 482 abstracts, of which 45 were screened to full review, and 11 met inclusion criteria. Six out of 11 trials were positive. The dorsolateral prefrontal cortex was the target in 218 patients (49.2%), and the primary motor cortex (M1) in 225 (50.8%). Studies targeting M1 at 10 Hz, with stimulation current delivered in the posterior-anterior, were systematically positive, frequently showing that maintenance sessions delivered weekly, and biweekly were able to maintain the analgesic effects seen after daily induction sessions. Studies assessing the effects of rTMS for FM are still marked by heterogeneity in stimulation petameters, choice of primary outcomes, and inclusion criteria. The selection of the stimulation parameters associated with significant analgesic effects is likely to benefit following larger multicenter trials and improve the overall management of pain and associated symptoms in people with FM.