Advancing Neuromodulation for Functional Movement Disorders: A Contemporary Narrative Review of Evidence, Gaps, and Future Outlook.

BACKGROUND

Functional movement disorders (FMDs) manifest as involuntary motor symptoms incongruent with known neuroanatomy. Once attributed to psychological factors, FMDs are now recognized as neurobiological conditions involving disrupted brain networks. They account for 2-20% of movement disorder referrals globally. While multidisciplinary rehabilitation benefits 60-70% of patients, 30-40% remain treatment-refractory, highlighting the need for biologically targeted therapies.

OBJECTIVES

This review synthesizes evidence on neuromodulation for FMDs, aiming to: (1) identify modifiable neural circuits, (2) evaluate clinical efficacy across phenotypes, (3) distinguish neurobiological from placebo-mediated effects, and (4) identify biomarkers for precision medicine.

METHODS

We conducted a narrative review (PubMed, Embase, 2000-2025), assessing risk-of-bias using RoB-2 and MINORS tools.

RESULTS

FMD pathophysiology involves cortical hyperexcitability, limbic-motor decoupling, and predictive coding deficits. TMS reveals reduced intracortical inhibition and shortened cortical silent periods in M1; fMRI shows altered emotional-motor connectivity. rTMS demonstrates therapeutic potential, though placebo responses are prominent. Anodal tDCS over the left DLPFC shows promise in functional dystonia, especially with comorbid anxiety.

CONCLUSIONS

FMDs reflect circuit-level dysfunction, supporting neuromodulation as a rational intervention. High-frequency rTMS over M1 and anodal tDCS over DLPFC yield modest clinical benefits, but placebo effects remain a confounder. Future progress requires addressing methodological gaps, validating biomarkers, and integrating neuromodulation within personalized, multidisciplinary frameworks that account for socioeconomic and psychosocial contexts to meaningfully reduce disability.