Background: Fibromyalgia syndrome (FMS) is a chronic pain disorder characterised by widespread musculoskeletal pain, fatigue, non-restorative sleep, and psychological comorbidities such as depression and anxiety. As pharmacological treatments show limited effectiveness, guidelines recommend multimodal approaches, including mind–body interventions. Biofeedback is one such option, providing real-time feedback on physiological signals to support self-regulation. A 2013 meta-analysis reported promising effects for EMG-based biofeedback on pain, whereas findings for other modalities or secondary outcomes were inconsistent. Since then, several randomised controlled trials (RCTs) have examined EEG- and HRV-based biofeedback and broadened assessed outcomes, yet results remain fragmented.
Objective: This systematic review aimed to update and synthesise RCT evidence on the efficacy of EMG-, EEG-, and HRV-based biofeedback in adults with FMS. The primary outcome was pain intensity at post-intervention. Secondary outcomes included health-related quality of life, sleep, fatigue, and psychological symptoms.
Methods: The review followed PRISMA 2020 and was registered with PROSPERO. A systematic search was conducted in PubMed, Web of Science, PsycINFO, and Scopus. Eligible studies were RCTs evaluating stand-alone biofeedback with a clearly defined control group. Risk of bias was assessed using RoB 2. Due to heterogeneity and incomplete reporting, a narrative synthesis was performed.
Results: Ten RCTs (13 reports; N = 600) met inclusion criteria. Overall risk of bias was predominantly high or raised some concerns. Across sham-controlled EEG neurofeedback trials, no consistent superiority over sham for post-intervention pain was found. EMG biofeedback showed heterogeneous findings, and several trials lacked complete between-group estimates. No HRV biofeedback trial reported a validated pain measure. Secondary outcomes showed no reproducible between-group differences. Adverse events, when reported, were mild.
Conclusion: Current RCT evidence does not support a reproducible short-term benefit of biofeedback over sham for pain in FMS. Effects against non-sham comparators are mixed, and reporting quality is limited. Further adequately powered sham-controlled trials with complete outcome reporting are needed.
