rTMS in Functional Motor Disorders: Review Finds Evidence Still Preliminary

A systematic review of 14 studies has found no sufficient evidence to establish the efficacy of repetitive transcranial magnetic stimulation (rTMS) in adults with functional motor disorders (FMD), even as preliminary data point to a striking pattern: inhibitory stimulation of the primary motor cortex produced the most consistent improvements in functional tremor, while excitatory stimulation showed conflicting results in functional weakness.

The review, published open-access in Clinical Neurophysiology and registered with PROSPERO as CRD420251250969, searched seven databases from inception to July 2026 and included both randomised and non-randomised interventional studies. The primary motor cortex (M1, the cortical region that sends descending motor commands) was the stimulation target in 11 of the 14 studies. Assessments of risk of bias and evidence certainty relied on PEDro, RoB 2, JBI tools and GRADE (a standard framework for rating confidence in effect estimates).

Because the studies differed substantially in protocol and population, the authors synthesised findings qualitatively rather than through meta-analysis.

What did the tremor data show?

Functional tremor emerged as the phenotype with the strongest signal. One small sham-controlled trial of inhibitory M1 stimulation found a significant group-by-time effect on tremor severity, with p=0.007. An uncontrolled prospective series reported a 40% reduction in postural tremor amplitude, though this result sat at the threshold of statistical significance (p=0.05).

The review rated GRADE certainty as moderate for tremor outcomes — the highest grade assigned anywhere in the analysis.

Why is functional weakness contested?

The picture for functional weakness, by contrast, is contradictory. Excitatory M1 stimulation increased objective strength by 25% versus 10% with sham in one trial (p=0.004). Yet the largest inhibitory sham-controlled trial in the review found no benefit at all (p=0.80).

That divergence frames the review's central hypothesis-generating observation: the direction of stimulation — inhibitory or excitatory — may interact with the clinical phenotype. The authors stress the finding warrants investigation, not adoption into routine protocols.

How safe is the intervention?

No severe adverse events were reported across the included studies. The reviewers note, however, that safety reporting was incomplete, which limits how firmly that reassurance can be stated.

What does this mean for practice?

For now, the authors conclude that rTMS should be considered an experimental, context-sensitive adjunct within multidisciplinary care for FMD — not an established therapy. Evidence certainty was very low for all outcomes except tremor, and the field lacks the adequately powered, phenotype-stratified, sham-controlled trials needed to justify phenotype-specific protocols.

The clinical stakes are considerable. Functional motor disorders — abnormal movements or weakness without a structural lesion explaining them — are common in neurology clinics and often respond poorly to medication. A targeted, non-invasive neuromodulation option would fill a genuine gap, but this review indicates the field has not yet cleared that bar.

The authors call for larger phenotype-specific randomised trials of rTMS in FMD, a recommendation likely to shape study design in neuromodulation laboratories over the coming trial cycle.